MINISTRY OF COMMUNICATIONS OF THE USSR

MAIN PATH DIRECTORATE

TECHNICAL INSTRUCTIONS FOR THE USE OF NON-WOVEN MATERIALS FOR REINFORCING THE SUB-SITE

TsP-4591

Moscow "Transport" 1989

IN Technical instructions requirements are set out for the design and calculation of anti-deformation structures made of non-woven material, laid to eliminate track subsidence, intense disorders of the rail track, slope slips, as well as to prevent the formation of ballast troughs and beds on the main platform of the roadbed and washouts. The basic provisions on the organization and technology of work during the construction of these structures are given. For engineering and technical workers of track facilities.

Responsible for the release of P.I. Dydyshko, V.V. Sokolov

Editorial Head V.G. Peshkov

Editor L.P. Topolnitskaya

INTRODUCTION

Stability railway track largely depends on the roadbed, which is approximately 70% of its length composed of clay soils. Under the combined influence of moving loads and climatic factors, the roadbed in these places is unevenly deformed. The main area (the interface between ballast materials and clay soils) is often affected by ballast troughs and beds. As a rule, the intensity of track disturbances in level and profile in these sections is increased. In some cases (approximately 1% of the total network length), track subsidence occurs, which is accompanied by uneven subsidence and shifts of the rail track, liquefaction of clay soil with splashes from under the sleepers, squeezing out masses of this soil onto the surface of the ballast prism. They intensify when the soil thaws and rain falls. In favorable engineering-geological conditions, deformations of the under-rail base can occur in places of increased dynamic impact of moving loads (switches, leveling spans of continuous track, etc.), as well as in heavily clogged areas,

IN modern conditions operation, the possibility of providing “windows” in the movement of trains to carry out work to strengthen the roadbed and the track as a whole at high traffic loads is limited. This forces us to reduce the volume of dugout work as much as possible and move to the use of artificial materials that have the necessary properties in anti-deformation structures.

For thermal insulation, foam plastic is used, which prevents seasonal freezing - thawing of clay soils; for hydraulic insulation, a polymer film is used, which prevents the infiltration of precipitation. Thermal and waterproofing coatings are laid within the ballast prism. The requirements for their design are set out in the Technical Instructions for eliminating the causes and subsidence of the railway track, TsP/4369.

Non-woven synthetic material, which is currently increasingly wide application during the construction and operation of structures for various purposes in our country and abroad, it is capable of separating and reinforcing soils, draining and diverting water. This material is made from synthetic fibers (waste, secondary raw materials or primary from the melt of polymers), which are mechanically joined together using needle-punching machines, where special needles entangle them in a layer. To produce materials, fibers from various polymers (polyester, polyamide, polypropylene, etc.) are used, the chemical and biological resistance of which ensures their service life in the ground for several decades. The use of natural fibers is excluded, since they are short-lived when working in the ground.

The most important properties of nonwoven materials include the following:

ability to retain small soil particles (filter property);

high water permeability;

high mechanical strength when stretched combined with elasticity and elongation ability;

Manufacturability of application (low consumption per unit area, ease of transportation, installation and connection).

Possessing the specified set of properties, the nonwoven material performs one of its functions - the role separating layer. The stress-strain state of the soil after laying, formed under the combined influence of loads and climatic factors nonwoven fabric changes. This layer prevents the manifestation of residual deformations of the soil, since the freedom of movement of individual particles is limited. They cannot pass through the material. This prevents the interpenetration of large particles into the clay soil and small particles into the draining soil. The shift of individual layers, aggregates or soil particles in the interlayer zone is difficult.

Reinforcing function of the material is that it is able to withstand tensile forces and increase the bearing capacity of the soil foundation reinforced with this material. In this case, the stresses in the soil mass are redistributed. The layer, working like a membrane, transfers some of the stresses, leveling them to a certain extent, from more loaded places to less loaded ones.

In the role reverse filter the material prevents mechanical suffusion, i.e. removal of small soil particles by water flow. In this case, in the direction of water movement in front of the layer of nonwoven material, as a result of re-sorting of particles, an additional natural soil return filter is formed.

The performance of non-woven fabric as drainage layer(drainage function) is possible due to its high water permeability along the canvas. For example, when the material is located on soil with a low filtration coefficient, the flow of infiltrated sediments, having reached the layer of this material, will begin to move along it. Some of the water will go down into the ground, but part of it will change its movement in the direction of less resistance and will be diverted away from the soil in need of protection.

These functions appear depending on the type of deformation being eliminated separately or, as is most common, together.

Non-woven material is used to eliminate and prevent track subsidence, intense disorders of the rail track, float of slopes of embankments and excavations, erosion of flooded slopes, uneven settlement of embankments in swamps, silting of drainages for various purposes, etc. In some cases, this material is used in combination with waterproofing film.

Some of the deformations practically or cannot be eliminated without the use of non-woven materials, or their elimination requires significant labor and material costs, as well as long interruptions in train traffic. Such deformations include subsidence of the track with the squeezing of liquefied soil onto the surface of the ballast prism, slopes floating due to surface waterlogging, washing out of soil from under the covering slabs of bank protection structures and flooded embankments, etc. Non-woven material is indispensable in those structures where, when using draining soil, it is necessary to perform work with high, often difficult to achieve accuracy (installation of a return filter in drainage and other structures).

The use of non-woven material coatings instead of traditional structures reduces the cost of eliminating and preventing deformations. At the same time, labor costs for maintaining the roadbed and the track as a whole are reduced, its major renovation or construction, the capacity of the lines increases, and significant savings are achieved.

These Technical Instructions contain basic provisions for obtaining initial data for design, conditions for the use of nonwoven materials, necessary requirements and recommendations for the construction of anti-deformation structures made of these materials, as well as the organization and technology of work.

The guidelines have been developed based on the results of experimental and pilot production use of non-woven material on railways, analysis foreign experience, laboratory tests and calculations.

Technical instructions were developed by VNIIZhT, KhabIIZhT, KhIIT, VNII of Transport Construction together with the Main Track Directorate of the Ministry of Railways and the Northern Railway.

1. GENERAL PROVISIONS

1.1. These Technical Instructions are intended for use by employees of services and track distances, track machine stations, engineering-geological bases and track survey stations, design organizations and construction departments in the appointment, design and implementation of measures to strengthen the under-rail base and other elements of the railway roadbed using non-woven materials .

1.3. Strengthening the roadbed with the use of non-woven materials in areas with track subsidence, slope failures of embankments and excavations, water erosion and other types of deformations in difficult engineering and geological conditions is carried out according to projects developed on the basis of terms of reference track service, which indicates a list of deformed sections according to operational observations and the technical passport of the track distance.

Work to eliminate intensive disorders of the rail gauge in level and profile using non-woven material is provided for in projects for major and medium track repairs. IN estimate documentation repairs include the specified work. The feasibility of use and specific areas for laying non-woven material are established on the basis of operational data on the condition of the track, labor costs for its maintenance, rail output, wear of superstructure elements and other indicators.

Together with the laying of non-woven material, the projects provide for the reconstruction or construction of new drainage systems to ensure the drainage of infiltrating sediments from the non-woven material covering,

1.4. Laying of coverings made of non-woven material is carried out as follows: independent work or together with major (medium) track repairs, providing for maximum mechanization using track, general construction earth-moving and special machines designed for repairing the roadbed. The work is carried out by track machine stations, including specialized ones, separate specialized columns of these stations and track distance teams.

1.5. The purpose of coverings made of non-woven material must be justified by a technical and economic comparison with other methods of eliminating deformations of the subgrade and strengthening the under-rail base (layout of the main site, arrangement waterproofing coating and etc.).

1.6. The main characteristics and location of laid non-woven material coverings, as well as changes in the nature and size of deformations after laying, are reflected in the established order in the appropriate forms technical passports path distances.

2. INITIAL DATA FOR DESIGN

2.1. The initial data for the design of anti-deformation structures using non-woven material on operating lines is obtained during an engineering-geological survey, which is carried out on the basis of the technical specifications of the track service.

2.2. During an engineering-geological survey to develop a project to eliminate deformations of the sub-rail base (track subsidence, intense disturbances of the rail track in level and profile on an unstable subgrade, uneven heaving of homogeneous soils), the site is inspected and recorded. characteristic features deformations and perform instrumental shooting. By drilling, digging or testing pits with sampling, the composition, composition and condition of the soils of the subgrade are determined. In this case, at least five points of the under-rail base (along the axis of the track, under both rails with their outside and at a distance of 20-40 cm from the ends of the sleepers) in the sleeper box and under the sleeper, the configuration of the surface of the clay soil is established on the main platform of the roadbed. Determine the presence and depth of location groundwater, sources of local soil moisture and other hydrogeological conditions. The required volumes and procedure for conducting engineering-geological surveys are established in accordance with the requirements of the Technical Instructions for eliminating heaves and subsidence of the railway track, TsP/4369.

3.2. To strengthen the subgrade, non-woven material is used, which must meet the following requirements:

Strip width, mm	more than 1700
Thickness, mm
Weight 1 m2, g	" 500
Breaking load, kgf, for a strip 5 cm wide in the direction:
longitudinal	" 60
transverse	" 30
Elongation at break, %, in the direction:
longitudinal	less than 80
transverse	" 140
Water permeability (filtration coefficient), m/day.	more than 10

3.3. In anti-deformation structures of the railway subgrade, it is possible to use a non-woven material that meets the stated requirements and is manufactured according to the technical specifications "Needle-punched fabric for road construction - Dornit. Technical specifications" TU 21-29-81-81, type 1, which is intended for high-grade roads bearing capacity. The use of material types 2 and 3 to reinforce railway subgrades is not permitted.

In addition, it is allowed to use nonwoven materials produced using other methods. technical specifications, including imported ones, if they meet the above requirements, as well as waste from chemical fiber factories non-woven fabrics for filtering viscose solutions, washed and sewn into strips.

The non-woven material is placed at a depth of at least 0.2 m below the bottom of the sleepers ( δ n) on the surface of ballast materials cut and leveled with a slope of at least 0.04 to the field side.

If the distance from the top of the ballast prism to the main platform of the subgrade is made of sandy loam and loam with a yield boundary w L

The covering is laid across the entire width of the subgrade on top. On double-track sections, in the absence of deformations on the adjacent track, it is possible to install covering only on one track.

Rice. 2. Schemes for laying a coating made of non-woven material to eliminate track subsidence and disorders of the rail track in level and profile on unstable sections of the roadbed in excavations:

A- on a single-track line; b, c- on a double-track line with one track and two tracks; 1 - non-woven material; 2 - ballast; 3 - clayey soils; 4 - drainage; 5 - tray

To eliminate track subsidence and track disturbances under turnouts, the coating must be of variable width. The edges of the covering are located behind the ends of the transfer bars by at least 0.9 m (). It is laid 0.2 m below the bottom of the beams with a slope of at least 0.02.

When constructing a covering under turnouts and on station tracks, a shallow drainage with a longitudinal slope of at least 0.03 is laid along it along the intertracks, the discharge from which is carried out by transverse drainage (see). To do this, use pipe filters or a “blind” drain with a diameter of at least 15 cm, which is made of crushed stone wrapped in non-woven material. The bottom of the drainage should be below the edge of the covering.

In the same way, if necessary, water is drained from between tracks on stretches in curved sections of the track.

When using crushed stone of normal size in the ballast layer, a layer of sand, asbestos ballast or small crushed stone of a fraction of 10-25 mm with a thickness of 5-10 cm is laid on the non-woven material.

When eliminating track subsidence, separate strips of nonwoven material in the covering are placed across the track, i.e., the length of these strips should be equal to the width of the covering. The strips must overlap each other by at least 0.2 m. When eliminating disorders of the rail gauge in level and profile on unstable sections of the roadbed, it is allowed to place strips of non-woven material along the track with a mutual overlap of at least 0.2 m.

In difficult engineering-geological conditions with intense track subsidence with squeezing out liquefied soil through ballast, non-woven material in the coating can be laid in two layers. In this case, crushed stone of normal size can be directly laid on non-woven material.

5. ELIMINATION OF DISORDERS OF THE RAIL GAUGE AT THE LEVEL AND IN THE PROFILE WITH THE FORMATION OF SPLASHES IN CLOGGED AREAS

5.1. Non-woven material is placed within the ballast prism at a depth of at least 20 cm from the bottom of the sleepers (Fig. 5, A).

Under the layer of non-woven material, the crushed stone must be cleared of debris to a depth of at least 10 cm in order to ensure the most complete and rapid removal of infectious moisture into this layer. Laying non-woven material on unplanned rollers of cleaned crushed stone in under-rail sections remaining after operation of the ballast cleaning machine is not permitted. This surface must be level.

In areas with a stable subgrade, where disturbances in the rail gauge in level and profile with the formation of splashes occur due to weeds, a continuous covering is installed; at the same time, in some justified cases, it is allowed to construct a covering only under joints, and in sections of continuous track - under leveling spans. On turnouts, it is allowed to lay material in the areas of the crosspiece and frame rail that are most susceptible to dynamic effects from moving loads. The edges of the covering must be at least 2 m from the joints.

To drain water in the transverse direction, the layer of non-woven material is brought up to the slope of the ballast prism on hauls, and on station tracks and turnouts - to shallow drainage. This drainage is arranged in accordance with the requirements.

5.4. The coating within the abutments of bridges, as well as the spans of reinforced concrete bridges running on ballast, is laid at the depth indicated above, reaching the sides of the ballast troughs (reverse walls of the abutments). Longitudinal drainage of water is carried out using drains, which are placed along these sides. The drains in this case can be made of non-woven material, which is rolled into a roll from a strip approximately 1 m wide.

6. APPLICATION OF COATING FROM NON-WOVEN MATERIAL AND WATERPROOFING FILM

The conditions for the use of this coating are set out in. Uneven heaving in homogeneous soils manifests itself in this case as a result of the existing (or ongoing) subsidence of the track. The ballast troughs and beds of varying depths that arise during these subsidences lead to increased uneven moistening of cohesive soils that are infiltrated with moisture. Due to its properties, non-woven material cannot be used independently to eliminate causes. It is used for this purpose in conjunction with a waterproofing film, which retains infiltrating precipitation.

Non-woven material covering structure and waterproofing film to eliminate heaves in the conditions under consideration, perform in accordance with the requirements set out in.

7. ELIMINATION OF SLOPE SLIDDS AND PATH SETTLEMENT ON UNSTABLE EMBARKES ON A SOLID FOUNDATION

7.1. On unstable areas of embankments, a coating of non-woven material or a combined coating of non-woven material and waterproofing film is laid, depending on the nature of the manifestation of deformations.

Finding the values Qi. We determine by well-known methods by solving the inverse problem the parameters c i And φi, which correspond to the limit equilibrium condition of this uncoated slope. For this case, as a result of the solution, the parameters were obtained c i=0.7ts/m2 and φi=8°.

Let us calculate the stability of a slope with a coating. We accept Within=0.14ts/m2, φin=36°. The thickness of the drainage soil layer on top of the non-woven material is 0.1 m. Angle β avg=27°. Values Qin we find for the density of the draining soil to be equal to 2 t/m 3.

We perform the calculation using the formula ().

First, let’s calculate the parameter included in the formula ()

ts;

ts.

Considering that Withi=0.7ts/m2, φi=8°, we find

Thus, with these parameters Within=0.14ts/m2 and φin=36° the required value of the stability coefficient is achieved TO " = 1,2.

Gaps and cracks on the surface of the slope are sealed with soil of homogeneous composition, compacting it. Depressions in which water can stagnate are eliminated by leveling and backfilling with local soil and compaction. If necessary, carry out partial cutting and cleaning of soil in places of uplifts, as well as in the lower part of previously floated massifs. To increase the adhesion of the non-woven material to the underlying soil, the grass on the slope is mowed, surface loosening is carried out manually or poured thin layer crushed stone, compacting it.

To prevent sliding of the draining soil between two layers of non-woven material, in this case it is possible to lay the triangular lattice described above or construct cages of stakes and poles. The top layer of non-woven material is put on the stakes through slits made in it.

When installing a covering made of non-woven material in combination with a counter-banquet to increase the stability of the slope, in the upper part of the embankment the structure is performed in accordance with the diagram shown in . Water drainage in the lower part of the covering is carried out by a longitudinal closed drainage constructed in the upper part of the counter-banquet. Drainage can be made of crushed stone wrapped in non-woven material, under the bottom of which a waterproofing film is laid in the form of a gutter. The longitudinal slope is provided at least 0.01.

The size of the counter banquet in this case can be reduced based on the calculation results using the above methodology.

Strips of nonwoven material in the coating are placed perpendicular to the axis of the path with an overlap, the size of which is set in accordance with the above calculation method, but not less than 0.2 m.

The covering from top to bottom should have a single strip without any extension. The strips are welded together on a slope with a blowtorch using a continuous seam or sewn together with nylon threads using a machine. The strips may not be connected under the ballast prism.

Before joining, the strips are pre-stretched by applying longitudinal direction load uniformly distributed across the width of the strip, equal to 20% breaking load. Methods for applying loads and changing strip sizes are established for given conditions by testing.

7.7. In difficult local conditions, including the occurrence of track settlements and drifts of embankment slopes in the area of culverts, in a pilot production procedure, anchoring of a coating made of non-woven materials in the upper part is carried out in accordance with the scheme without placing the coating under the rail and sleeper grid. The material is wrapped through reinforced concrete beams laid on the side of the road, which rest against beams placed on the slope across the axis of the track. It is pinched due to subsequent loading from above. The length of the pinched part is determined by calculation.

In order to ensure their stability when working in compression under the influence of shear forces, cross beams are made of reinforced concrete with a cross-section of 0.2 x 0.2 m on site or assembled from old reinforced concrete sleepers, connecting them rigidly to each other. In the latter case, the sleepers are laid on their sides, with their beds facing each other, and tightened with two bolts with a diameter of 22 mm through through holes. To ensure the required total length of the cross beams at one end, the sleepers are connected to each other with clamps. Prefabricated beams (old-fashioned reinforced concrete sleepers) are laid across the rows of these beams, leaning on them.

Lattice of timber outside culvert is held in place by stops. The design and dimensions of the stops are determined by calculation. Above the head of the pipe, the grating rests on a beam placed parallel to the axis of the track and monolithic for collaboration with cross bars.

Strips of non-woven material are connected to each other in the manner described above (see), after stretching them out. To increase the holding forces, the non-woven material can be “sewn” to the ground at the joints of the strips with stakes 1-1.5 m long every 1.2 m. In this case, welding or stitching of the strips is not required.

The coating on the slope is covered with a layer of drainage soil on top, the thickness of which is set in accordance with the calculation outlined above (see).

7.8. Anchoring of the covering at the top of the embankment outside the culvert on a potentially unstable section of the slope can also be carried out in accordance with the diagram.

The procedure for performing work when installing the coating is set out in these Instructions.

8. ELIMINATION AND PREVENTION OF DEFORMATIONS OF CUTTING SLOPES

8.1. Non-woven material is used both to prevent possible soil mixing on slopes and to stop the further development of already manifested deformations. Laying non-woven material on a slope is allowed when the depth of development of deformations does not exceed the maximum depth of soil freezing in a 10-year period.

Non-woven material is used for all types of clay soil characterized by moisture along the yield line wL≤0,45.

The coating, by passing water through itself and retaining soil particles, acts as a return filter on slopes, including when groundwater emerges here. As a result, soil washouts and flows stop. In addition, the stability of the slopes increases due to the additional holding forces that arise.

8.2. Calculation of excavation slope stability is carried out according to the methodology set out in these Guidelines. Determine by calculation required amount layers of non-woven material of a given strength, the thickness of the layer of drainage soil on top of the non-woven material and the parameters of pinching the coating in the off-slope part of the excavation.

8.3. Before laying the material, cracks between the floated massifs are sealed with local soil and depressions on the slope are eliminated. If necessary, partially remove the soil from the lower part of the floated massifs. It should be taken into account that this part is supporting and its excessive removal will lead to disruption of the existing balance of the slope, therefore, when cleaning, it is enough to ensure the normal operation of drainage systems in the excavation.

8.4. Non-woven material is laid on the slope prepared in this way in the deformation area and beyond, at least 10 m in each direction along the entire height. The covering in the upper part is extended from the edge to the field side by a distance of at least 2 m (Fig. 11, A). In the lower part, if necessary, the cell shelf is covered with material and the cell is lined. The material must be “sewn” to the slope with stakes. The length of the stakes driven into the ground through cuts in the material should be 1.2-1.5 m. They are not driven to the end by 0.1-0.2 m. They are placed from each other at a distance of at least 1 m.

non-monolithic prefabricated concrete plates measuring 1x1 m or reinforced concrete slabs measuring 3x2.5 m with flexible connections on a 10 cm layer of crushed stone placed on non-woven material ();

prefabricated reinforced concrete slabs measuring 3x2.5 m with drainage holes, sealed along the contour with a TsNIIS key, on non-woven material ().

9.3. If the slopes are composed of clayey sands, sandy loams, loams or clays, then for all of the specified types of coatings, a layer of sand 10 cm thick is required between the soil of the slope and the non-woven material. The fractional composition of the layer is selected in accordance with the requirements of SNiP II -53-73 “Dams from local materials ".

9.8. The consequences of erosion on operating lines are eliminated using non-woven material (). The erosion funnel is filled with local soil or stone. The non-woven material covers the entire erosion area with a margin for the depth of the total erosion and is pressed against the rock riprap, concrete blocks and other materials.

When the slope of the mineral bottom of the swamp is up to 1:5, work on laying soil on both sides of the embankment is carried out simultaneously both during the construction of the field parts of the berms and when filling the space between the field parts and the sinus embankment. If the slope is steeper, to avoid shifting the embankment, first construct a berm on the downstream side. The sinuses are filled after the immersion of the berms into the swamp has sharply slowed down or stopped.

The non-woven material is laid in two layers: in the transverse and longitudinal directions. At the same time, a reserve of width is provided on the field side of the berm and on the slope of the existing embankment to compensate for the changes in the size and shape of the coating that occur when it is immersed in the swamp under the weight of the dumped soil. The size of the margin on each side should be taken equal to 1.5 N more. The strips of non-woven material in both layers overlap each other by at least 0.2 m. They are welded or sewn together with a continuous seam.

10.2. Embankments built on weak foundations are characterized by significant deformations. The embankments not only settle into the ground, but also spread to the sides, and deformations during operation continue, without fading, for a long time.

Non-woven material does not prevent soil consolidation. However, its use in the construction of embankments on weak grounds in difficult engineering and geological conditions allows to obtain: uniform settlement of the soil base; preservation of the design contours of the embankment and prevention of spreading and uplift of the base; reducing the volume of soil filling by reducing the settlement of the embankment and foundation during operation and maintaining the interface between soils without their interpenetration.

Rice. 16. Scheme of layer-by-layer filling of loading berms when stabilizing embankments in swamps:

1 - existing embankment: 2 - field part of the berm; 3 - non-woven material;

I - VII - sequence of laying soil in berms

10.3. Non-woven material is used in type I swamps with a peat deposit thickness of up to 1.5 m and on a base consisting of silty and peaty soils, including mari. In addition, it is used on a foundation made of waterlogged clay soils ( I L>0.5) under embankments up to 1 m high in the zone of high-temperature permafrost.

10.4. When preparing the base for laying non-woven material, bushes are cut down, trees are cut down, and the covering is placed across the entire width of the embankment at the bottom. The number of layers of non-woven material under the embankment must be selected so that their total tensile strength is at least 1.5 tf/m at an embankment height of up to 2 m and at least 2 tf/m at an embankment height of 2 to 4 m.

Strips of non-woven material are laid on the base in a direction transverse to the axis of the track, connecting them in accordance with the requirements. Filling of soil until a layer of 0.5 m is created above the non-woven material is done using the “from the top” method.

10.5. When using non-woven material at the base of the embankment, berms are not installed. The work is carried out without damaging the moss-peat cover, including in the warm season, without waiting for the active layer to freeze.

11. APPLICATION OF NONWOVEN MATERIAL IN DRAINAGES

11.1. Non-woven material is used as a return filter in drainages in accordance with the diagrams in Fig. 17. Drains are installed in combination with anti-deformation structures for various purposes: anti-heaving cushions, heat and waterproofing layers, coatings made of non-woven material or combined coatings on the main site, embankment slopes, etc. In addition, closed drains with a return filter made of non-woven material constructed to improve drainage conditions in recesses, including flooded ones, under “buried” ditches, on switch necks to drain water from switch drives, when installing transverse water discharge at stations, double-track and multi-track lines.

11.2. "Blind" drains (Fig. 17, A) is performed by wrapping crushed stone from poorly weathered rocks with a particle size of more than 40 mm in non-woven material. The diameter of this drain is taken to be at least 20 cm. When using perforated pipes or pipe filters according to the diagrams in Fig. 17, b, V For backfilling, medium- and coarse-grained sand is provided. The material for filling the trench above the closed drainage is selected based on its operating conditions. To prevent mechanical suffusion of soil behind the walls and under the bottom of trays constructed in difficult hydrogeological conditions, it is advisable to additionally lay a layer of non-woven material (Fig. 17, G), which will act as a reverse filter.

Rice. 17 . Scheme drainage devices with non-woven return filter:

a - “blind” drain; b - pipe with drainage backfill; c - “pipe in a shell”; g - tray with an external filter; 1 - backfilling the trench; 2 - non-woven material; 3 - crushed stone; 4 - drainage material; 5 - perforated pipe; 6 - tray

12. PROTECTIVE LAYER OF NON-WOVEN MATERIAL ON THE MAIN AREA OF THE SUBGRAD

12.1. A protective layer of non-woven material on the main platform of the roadbed is laid to strengthen the path when installing mortise pads and planning this site in accordance with Technical Instructions TsP/4369. It increases the bearing capacity of the soil, prevents the formation of ballast troughs and beds, track subsidence and uneven heaving.

12.2. Non-woven material should be used in excavations, on zero places and embankments in clay soils of all types, with the exception of sandy loams containing sand particles ranging in size from 2 to 0.05 mm in an amount of more than 50% by weight. For clayey soils with moisture content at the yield point wL>0.23, as well as with increased natural moisture content of clay soils characterized by wL ≤ 0.23 and turnover rate I L>0.25, a drainage pad must be laid on top of the non-woven material.

12.3. Thickness of drainage pad h z should be prescribed in accordance with table. 3 and 4 depending on: the type of soil (humidity at the yield point wL) and freezing depth h according to the table 3; on the condition of the soil (fluidity indicator I L) according to table 4. Moreover, for soils with wL≥0.23, the greater of the values given in Tables 3 and 4 is accepted.

12.4. A diagram of the construction of a subgrade with a drainage pad on top of a non-woven material is shown in. The surface of clay soil on single- and double-track lines is planned in both directions from the axis of the roadbed with a slope of 0.04.

Table 3. Thickness of drainage pad

Soil moisture at the yield point w L	Meaning h h along the axis of the path, cm, at freezing depth h pr, m
Soil moisture at the yield point w L	UP TO 1.5	1,5-2	2-2,5
0,23-0,35
0,36-0,40
0,41-0,45
0,46-0, 50
0,51-0,55

Table 4. Thickness of drainage pad

Rice. 18. Scheme of the construction of a subgrade with non-woven material and a drainage pad:

A- in the embankment; b- in the recess; 1 - crushed stone; 2 - ballast cushion; 3 - drainage pillow; 4 - non-woven material

12.5. To construct a cushion, it is necessary to use sand, with the exception of dusty ones, coarse soils (with maximum size fractions 300 mm) or coarse soils with sand filler.

13.2. Based on standard technological processes, repair departments (in some cases, design organizations) draw up a working technological process for carrying out work. To determine labor costs, a list of machines and mechanisms, and clarify the scope of work, one should use technological processes No. 5-9 for installing mortise anti-heaving cushions and major repairs of the track with the layout of the main subgrade area, which are included in the technological processes for major repairs of the railway subgrade, as well as technological processes of major track repairs with lowering or maintaining longitudinal profile elevations.

13.3. Work on laying non-woven material is divided into preparatory main and final.

13.4. During preparatory work mark the boundaries of the cutting of soil under the rail base and fix the sections of the beginning and end of laying the coating and the boundaries of the bends. To do this, make marks on the adjacent path or hammer pegs to the side.

To ensure normal operation of the machines, site preparation includes: removing obstacles that could cause stopping or damage to the machines, removing paving, soil and flooring at crossings, preparing places for earth-moving equipment to enter and exit the track.

In accordance with the project, individual strips of material are measured and cut, taking into account their overlap in the longitudinal and transverse directions. The prepared strips are wound into separate rolls, which are laid out within the work area.

To reduce the volume of crushed stone that must be cut by earth-moving machines into the main “window”, a side cut of the ballast prism arm is made with the ballast dump beyond the curb. Before cutting out the ballast, a place is prepared for its placement outside the dimensions: the ditches are cleared of vegetation and stagnant areas are eliminated. To drain water, drainage pipe filters or “blind” drains made of crushed stone wrapped in non-woven material are placed at the bottom of the ditch. To reduce the volume of cut crushed stone placed in the excavation, part of the crushed stone is cut out by a ShchOM-4 machine and then removed by an SM-2 machine.

Using old grate During the preparatory work, new sleepers are brought in and the unsuitable ones are replaced, the bolts in the joints are tested, and the sleepers are secured by finishing off the spikes.

Before the start of the main work, using levels installed for the entire period of the “window”, the existing marks of the top of the sleepers along the axis of the track are removed in sections fixed at 10 m intervals in order to control the design marks during cutting out the soil and leveling the base.

13.5. The main work includes: dismantling the rail and sleeper grid, cutting out the soil, planning the base of the covering and bends, laying out strips of non-woven material, laying the rail and sleeper grid, ballasting, lifting and straightening the track.

If the laying of non-woven material on the main platform of the roadbed is carried out as an independent work, then the rail and sleeper grid is disassembled and laid with one track-laying crane. In this case, depending on the conditions of placement of work trains, the possibility of passing the maximum train traffic during work and other factors, either the reverse order of formation of work trains is adopted, i.e., the straightening and tamping machine is sent first to the haul, then the ballaster, the composition of the hopper-dosers , the track-laying train, or the rail and sleeper grid is disassembled by the track-laying machine in the opposite direction, starting from the end of the section.

When laying non-woven material in conjunction with a major overhaul of the track's upper structure, the procedure for forming work trains and carrying out work is determined by standard technological processes.

To facilitate the work of the laying crane, the rail and sleeper grid is torn off from the ballast prism before disassembly using an electric ballaster, a crushed stone cleaning machine or a VPO-3000 machine. At the end of the work, the SCHOM machine, as well as the track plow, which performed the preliminary bead cutting, are overtaken along the adjacent track to perform operations in accordance with the technological process.

Earth-moving machine kits are used to cut ballast and level the foundation. When using sets of earth-moving machines recommended for lowering the elevations of the longitudinal profile of a railway track, labor costs and time to complete the work are determined in accordance with the technical standards given in standard technological processes.

In the absence of standard kits, the number of machines and their operating time are selected in accordance with the volume of work on cutting and leveling ballast and the productivity of the machines (Tables 5 and 6). Bends are planned with a slope of 0.02.

Table 5. Volumes earthworks carried out when laying a covering length of 100 m

Indicators	Laying depth of coating, cm
Indicators
Branch length, m
Cutting volumes, m 3:
on the main site
" tap
Total
Layout area, m2

On double-track sections, where the total load on both tracks does not exceed 55 pairs of trains per day, a track plow can be used to cut ballast. The thickness of the ballast layer cut off in one pass of the plow is approximately 5-8 cm. When using a plow, it is also necessary to use a bulldozer, which will level the roadside.

In areas with splashes from weeds, the layer of crushed stone under the non-woven material is cleaned with a BMS machine. In this case, the machine leveler must be installed in such a way that the base under the non-woven material is leveled without rollers of cleaned crushed stone under the rail threads and without a groove in the middle of the track.

When placing strips of material along the axis of the track, the spreading is carried out starting from the side of the road to the inter-track with the corresponding overlap of the strips.

Table 6. Machine occupancy time when performing excavation work on an area of 100 m

Types of jobs	Time consumption, machine-hours, with coating laying depth, cm
Types of jobs
Ballast cutting:
bulldozer with straight blade power up to 59 kW
bulldozer with straight blade power up to 96 kW
bulldozer with rotary blade power up to 96 kW (layered)	0,68	0,91	1,14	1,37	1,88
Base layout:
bulldozer power 79 kW					0,81	0,81
79 kW motor grader

The links of the rail and sleeper grid are laid directly on the non-woven material. It is not allowed to turn over the first links of the track-laying train's rail packages on the surface.

The track is lifted onto ballast without the use of strings in several passes of an electric ballaster, crushed stone cleaning machine or VPO-3000 machine. The lifting height in one pass should be no more than 10 cm when using ShchOM and ELB machines and no more than 8 cm when using a VPO-3000 machine. The first lifting is carried out using fine ballast (see). After each lifting of the track, ballast is re-unloaded from the hopper-dispensers. With this technology, it is advisable to install the ballaster between two groups of cars with ballast.

The use of VPO-3000 and VPR machines is allowed after a layer of ballast with a thickness of at least 20 cm is placed between the sole of the sleepers and the covering of non-woven material. With a smaller thickness of this layer, the use of these machines is prohibited, since their working parts will damage the coating.

The first two trains pass at a speed of 25 km/h, and the subsequent ones at 60 km/h.

13.6. Final works are carried out in accordance with standard technological processes for major and medium track repairs. During final works plan roadsides, remove excavated soil, arrange drainage systems in accordance with the project.

LAYING A COVERING OF NON-WOVEN MATERIAL AND WATERPROOFING FILM ON AN UNSTABLE EMBARK

13.7. During the preparatory period, in accordance with the project, strips of non-woven material and film are measured, cut and numbered in the required sequence.

The length of a continuous strip of film should be equal to the unfolded width of the coating on slopes and within the main area. Strips of nonwoven material are cut for two layers. In this case, the full length of the strip can be assembled from three" (or two) separate parts: for slopes and the main platform. On the side, strips of non-woven material are welded into panels of such a size that they can be moved to the installation site. Panels for slopes and the main area pads can be welded separately.

13.8. The main work is carried out through the “window” with the removal of the rail and sleeper grating. Old ballast is cut down to design marks using bulldozers, scrapers or a snow plow from an adjacent track (on a double-track section). The panels of non-woven material mounted for the main site are laid on the planned base. Film strips are laid across the path, overlapping them by at least 0.25 m. In this case, the required part of the film strips is placed on the main site, and the remaining parts intended for slopes are left rolled up on the roadsides.

A second layer of nonwoven material is placed on top of the film. In parallel with these works, enclosing drainages are installed along the edges of the coating. A rail and sleeper grid is laid on the covering made within the main area and the track is ballasted.

13.9. Work on the installation of pavement within the slopes can be carried out without interruption in train traffic. At the same time, the necessary leveling and cutting of soil on slopes is carried out manually. The slope panels are welded on the side of the road with the lower panel on the main site. From the wound rolls, strips of film with overlap are rolled out along the slope and the top panels of non-woven material are mounted on top of them by welding together. It is advisable to lay covering materials on slopes from the top of the embankment.

Film and non-woven material are launched into dug drainage ditches. A separate longitudinal strip of film is placed under the film strips perpendicular to the ditches, covered with non-woven material, crushed stone is poured on top and wrapped with this material.

The covering on the slopes and roadsides is covered with a layer of drainage soil, bringing the slope to the design outline.

STRENGTHENING FLOODED SCOPE

13.10. When performing construction and installation work to protect the slopes of structures with rock fill and prefabricated concrete and reinforced concrete slabs, it is necessary to be guided by the current standards, building codes and these Technical Instructions.

13.11. Before laying the slabs, the soil at the base of the covering (on the slope) is compacted and control tests of its density are carried out, and thrust structures (tooth) are constructed at the base of the embankment. For the work performed, the appropriate executive documentation, including acts of hidden work.

13.12. The planning of slopes for laying non-woven material is carried out by mechanisms with the surface of the slope being adjusted to the design marks manually. Deviation from the design surface of the slope is allowed no more than ± 5 cm over a length of 3.0 m.

Preparation of the base for laying non-woven material and its laying on the slope is carried out in small areas, on the volume of work performed during the day. IN winter conditions strips of non-woven material are rolled out immediately before laying the next batch of slabs on a slope cleared of snow.

If, before laying the slabs, the planned slope is washed out by surface, rain or river water, then the surface of the slope is brought to the design marks by adding small crushed stone, sand and gravel mixture or coarse sand with moisture, while removing and laying again non-woven material in areas of erosion.

13.13. Strips of non-woven material are laid along the slope from top to bottom with a mutual overlap of 10 cm and connected with a continuous seam using a blowtorch welding. The panels are secured against displacement by loading, pinning, pins, staples or wooden stakes.

13.14. When installing riprap, the stone is poured using vibrating chutes, a bucket transported by a crane, or an excavator bucket.

When leveling stone on a non-woven material covering, it is necessary to monitor the integrity of the sheets and butt joints. Leveling crushed stone preparation for laying neomonolithic slabs with flexible connections (see Fig. 13, b) are performed manually. If the non-woven material is damaged, the gaps are covered with pieces of this material, providing an overlap of at least 0.2 m. The pieces of material are welded to the main fabric.

Reinforced concrete slabs are laid according to the maps from bottom to top, guided by the requirements of VSN 82-69 and the following instructions.

Slinging of slabs should be done in such a way that the planes of the slabs when lowering them are parallel to the surface of the slope.

For this purpose, traverses or slings of different (locally selected) lengths are used.

When installing adjacent slabs, monolithic along the contour with a TsNIIS key, stop templates are used, the dimensions of which provide the required gap between the slabs.

The displacement of the edges (ends) of the slabs along a line parallel to the edge of the slope should be less than 5 mm, but the normal to it should be less than 10 mm.

13.15. After laying on the slope, the slabs are welded into cards. Before welding, in the places where it is produced, the non-woven material in the seam is sprinkled with sand in a layer of 3-4 cm.

Immediately before grouting, seams and welded joints are thoroughly cleaned of sand and debris. The quality of welded joints and seam cleaning is confirmed by a certificate.

13.16. The seams are cemented with high-strength fine-grained concrete of grades 400-500 with the largest aggregate size of 10-15 mm. Compaction of the concrete mixture should be carried out using standard mechanical vibratory compactors. Consolidation work should be carried out at stable positive temperatures.

APPLICATION.

Test method for nonwoven material

The general conditions for testing non-woven material must comply with "Textile non-woven fabrics. Rules for acceptance and sampling."

Linear dimensions and the mass of non-woven material is determined according to GOST 15902.1-80 "Non-woven fabrics. Determination methods linear dimensions and the masses."

Strength nonwoven material under uniaxial tension is established in accordance with "Nonwoven fabrics. Methods for determining strength."

Uniaxial tension reflects the performance of a nonwoven fabric laid on a slope to improve stability. The safety factor of a nonwoven material under uniaxial tension, taking into account the joint work of this material with the soil due to friction and adhesion forces, is taken equal to n = 1,2.

The non-woven material is tested for biaxial tensile and water permeability on non-standard models.

Biaxial tension the condition characterizes the operation of non-woven material in the under-rail base: in the ballast prism, on the main platform of the roadbed, under the embankment. Tests are performed on a model of a square membrane with a side size of 105 mm. The sample is fixed in a frame on all sides. Apply evenly to the membrane surface distributed load, the size of which increases until the material fails. Stress in the membrane in two mutually perpendicular directions (without taking into account anisotropy)

Where E- elastic modulus of the material, kgf/cm 2 ; R- load on the membrane surface, kgf/cm 2, b, t- geometric dimensions of the membrane, cm.

Meaning σ xc= σ yc, obtained empirically for specific type material is taken as the limit in calculations.

Vertical water permeability TO Nonwoven material can be determined in serial devices for sandy and clayey soils (for example, SPECGEO tube, Kamensky tube, F-1M device), placing the material in them in several layers (in a stack). The method is applicable for both two-layer (non-woven material and primer) and single-layer (non-woven material) media.

Horizontal water permeability(along the layer of material) TO G is determined in special device, consisting of a metal glass with perforated walls. The height of the perforated part corresponds to the height of the layer (stack) of material. A piston with a hole is placed on top of the material certain radius in the center.

Through this hole, water enters the material under pressure and is filtered only in the horizontal direction. Filtration coefficient along the material layer

Where l n - piston length, m; R- outer radius of the piston (sample), cm; r- internal radius of the piston, cm; Q- water consumption, m 3 /s; H- sample height, m; ∆h- pressure in the sample, m.

A load corresponding to the actual operating conditions of the nonwoven material layer in the structure can be transferred to the piston.

The card is intended for rational organization labor of workers engaged in arranging a layer of synthetic non-woven material (dornite) at the base of the subgrade (on a grip 50 - 100 m long) with rolling out the material in the longitudinal direction.

Designation:	KTP 6.03.1.2002
Russian name:	Installation of a layer of synthetic non-woven material (dornite) at the base of the subgrade with rolling out the material in the longitudinal direction
Status:	no expiration date set
Replaces:	KT 10.5.1.90
Date of text update:	05.05.2017
Date added to the database:	01.09.2013
Effective date:	01.01.2002
Approved:	01.01.2002 Rosavtodor
Published:	State Enterprise Tsentrorgtrud Rosavtodor (2002)
Download links:

MINISTRY OF TRANSPORT OF THE RUSSIAN FEDERATION

STATE ROAD SERVICE
(ROSAVTODOR)

CENTER
ORGANIZATION OF LABOR AND ECONOMIC
MANAGEMENT METHODS
(TSENTRORGTRUD)

COLLECTION OF CARDS
LABOR PROCESSES FOR CONSTRUCTION,
REPAIR AND MAINTENANCE OF HIGHWAYS

Work process map

Layer device
made of synthetic non-woven material (dornite)
at the base of the subgrade
with rolling out the material in the longitudinal direction

KTP-6.03.1-2002

Second edition, revised and expanded

(Issue 6)

Moscow 2002

Cards labor processes designed to improve the organization of labor of workers engaged in construction, repair and maintenance highways.

The maps determine the progressive technology of work, rational use working hours, technological sequence of work performance based on advanced techniques and labor methods.

Maps can be used in the development of organizational and technological documentation for the construction, repair and maintenance of highways (PPR and others), work planning, as well as in educational purposes in the training of highly qualified workers.

A collection of maps of labor processes prepared by engineers A.I. Anashko, E.V. Kuptsova, T.V. Insurance.

Responsible for the release A.A. Morozov.

. Scope and effectiveness of the card

The name of indicators

Unit

Value of indicators

according to TE, EniR

Output per 1 person-day

Labor costs for constructing 100 m 2 layers of synthetic non-woven material (dornite)

Note: Labor costs include time for preparatory and final work - 2% and rest - 13%.

Using the card will increase labor productivity by up to 5 - 6%.

2. Preparation and conditions for performing the process

Name

Bulldozer on a T-130 tractor

Roller DU-29 (D-624)

Folding knife

Shovel

Fastening brackets

Typical fencing and safety signs

M 1 - brings the unit into working position, performs leveling and lays it in accordance with the design profile. At idling carries out partial compaction of the embankment.

Compacting the soil of the base of the embankment in 6 passes along one track

M 2 - brings the unit into working position and performs compaction with 6 passes of the roller with a turn on the embankment.

Preparing dornite rolls for rolling

D 1, D 2, D 3 - bring the dornite roll to the rolling site. At the ends of the grip, where the dornite is rolled out, beacon markers are placed.

Rolling out rolls in the longitudinal direction, cutting sheets, fastening with staples

D 1, D 2 - rolls are rolled out manually across the entire width of the base. D 3 - after rolling out the first meters, the edge part of the web is secured with 3 staples, and during further rolling - after 1.5 - 2 m. At the end of the gripping, the web is cut off (D 3) from the roll with a knife and turned 180° (D 1, D 2), continuing rolling in the opposite direction, overlapping with an overlap of at least 15 cm.

Quality control of work performed, correction of defects

D 1, D 2, D 3 - after rolling out all the dornite, the quality of the laid layer and the quality of joining of the panels are checked by visual inspection. Move to the next capture.

Development of soil of group II with a movement of 20 m for backfilling of dornite

M 1 - brings the unit into working position and develops, moves and unloads soil onto the underlying layer of dornite with an empty return to the face.

Leveling the soil with a bulldozer

Soil compaction in 6 roller passes along one track

Active

Approved by the Ministry of Railways on May 3, 1988.

The Technical Instructions set out the requirements for the design and calculation of anti-deformation structures made of non-woven material, laid to eliminate track subsidence, intense disorders of the rail track, slope slips, as well as to prevent the formation of ballast troughs and beds on the main platform of the roadbed and washouts. The basic provisions on the organization and technology of work during the construction of these structures are given.

For engineering and technical workers of track facilities.

Responsible for the release: P.I. Dydyshko, V.V. Sokolov

Editorial Head V.G. Peshkov

Editor L.P. Topolnitskaya

Issued by order of the USSR Ministry of Railways

INTRODUCTION

In conditions of increasing freight intensity and loads from rolling stock on the rails and increasing train speeds, the intensity of track disturbances increases, which adversely affects the carrying capacity of railways.

The stability of the railway track largely depends on the roadbed, which is composed of clay soils for approximately 70% of its length. Under the combined influence of moving loads and climatic factors, the roadbed in these places deforms unevenly. The main area (the interface between ballast materials and clay soils) is often affected by ballast troughs and beds. As a rule, the intensity of path disorders in terms of level and profile in these areas is increased. In some cases (approximately 1% of the total network length), track subsidence occurs, which is accompanied by uneven subsidence and shifts of the rail track, liquefaction of clay soil with splashes from under the sleepers, and squeezing out masses of this soil onto the surface of the ballast prism. They intensify when the soil thaws and rains fall. In favorable engineering-geological conditions, deformations of the under-rail foundation can occur in places of increased dynamic impact of moving loads (switches, leveling spans of continuous track, etc.), as well as in heavily clogged areas.

In modern operating conditions, the possibility of providing “windows” in the movement of trains to carry out work to strengthen the roadbed and the track as a whole with high traffic loads is limited. This forces us to reduce the volume of excavation work as much as possible and switch to the use of artificial materials that have the necessary properties in anti-deformation structures.

For thermal insulation, foam plastic is used, which prevents seasonal freezing - thawing of clay soils; for hydraulic insulation, a polymer film is used, which prevents the infiltration of precipitation. Thermal and waterproofing coatings are laid within the ballast prism. The requirements for their design are set out in the Technical Instructions for eliminating the causes and subsidence of the railway track, TsP/4369.

Non-woven synthetic material, which is currently finding increasing use in the construction and operation of structures for various purposes in our country and abroad, is capable of separating and reinforcing soils, draining and removing water. This material is made from synthetic fibers (waste, secondary raw materials or primary from the melt of polymers), which are mechanically joined together using needle-punching machines, where special needles entangle them in a layer. To produce materials, fibers from various polymers (polyester, polyamide, polypropylene, etc.) are used, the chemical and biological resistance of which ensures their service life in the ground for several decades. The use of natural fibers is excluded, since they are short-lived when working in the ground.

The most important properties of nonwoven materials include the following:

ability to retain small soil particles (filter property);

high water permeability;

high mechanical tensile strength combined with elasticity and elongation ability;

Manufacturability of application (low consumption per unit area, ease of transportation, installation and connection).

Possessing the specified set of properties, the nonwoven material performs one of its functions - the role separating layer. The stress-strain state of the soil that has developed under the combined influence of loads and climatic factors changes after laying the nonwoven material. This layer prevents the manifestation of residual deformations of the soil, since the freedom of movement of individual particles is limited. They cannot pass through the material. This prevents the interpenetration of large particles into the clay soil and small particles into the draining soil. The shift of individual layers, aggregates or soil particles in the interlayer zone is difficult.

Reinforcing function of the material is that it is able to withstand tensile forces and increase the bearing capacity of the soil foundation reinforced with this material. In this case, the stresses in the soil mass are redistributed. The layer, working like a membrane, transfers some of the stresses, leveling them to a certain extent, from more loaded places to less loaded ones.

In the role reverse filter the material prevents mechanical suffusion, i.e. removal of small soil particles by water flow. In this case, in the direction of water movement in front of the layer of nonwoven material, as a result of re-sorting of particles, an additional natural soil return filter is formed.

The performance of non-woven fabric as drainage layer(drainage function) is possible due to its high water permeability along the canvas. For example, when the material is located on soil with a low filtration coefficient, the flow of infiltrating sediments, having reached the layer of this material, will begin to move along it. Some of the water will go down into the ground, but part of it will change its movement in the direction of less resistance and will be diverted away from the soil in need of protection.

These functions appear depending on the type of deformation being eliminated separately or, as is most common, together.

Non-woven material is used to eliminate and prevent track subsidence, intense disorders of the rail track, float of slopes of embankments and excavations, erosion of flooded slopes, uneven settlement of embankments in swamps, silting of drainages for various purposes, etc. In some cases, this material is used in combination with a waterproofing film.

Some of the deformations practically or cannot be eliminated without the use of non-woven materials, or their elimination requires significant labor and material costs, as well as long interruptions in train traffic. Such deformations include subsidence of the track with the squeezing of liquefied soil onto the surface of the ballast prism, slopes floating due to surface waterlogging, washing out of soil from under the covering slabs of bank protection structures and flooded embankments, etc. Non-woven material is indispensable in those structures where, when using draining soil, it is necessary to perform work with high, often difficult to achieve accuracy (installation of a return filter in drainage and other structures).

The use of non-woven material coatings instead of traditional structures reduces the cost of eliminating and preventing deformations. At the same time, labor costs for the maintenance of the subgrade and the track as a whole, its major repairs or construction are reduced, the throughput of the lines is increased, and significant savings are achieved.

These Technical Instructions contain basic provisions for obtaining initial data for design, conditions for the use of nonwoven materials, necessary requirements and recommendations for the construction of anti-deformation structures from these materials, as well as the organization and technology of work.

The instructions were developed based on the results of experimental and pilot production use of non-woven material on railways, analysis of foreign experience, laboratory tests and calculations.

Technical instructions were developed by VNIIZhT, KhabIIZhT, KhIIT, VNII of Transport Construction together with the Main Track Directorate of the Ministry of Railways and the Northern Railway.

1. GENERAL PROVISIONS

1.3. Reinforcement of the roadbed with the use of non-woven materials in areas with track subsidence, drift of slopes of embankments and excavations, water erosion and other types of deformations in difficult engineering-geological conditions is carried out according to projects developed on the basis of the technical specifications of the track service, which indicates a list of deformable sections according to data operational observations and technical passport of the track distance.

Work to eliminate intensive disorders of the rail gauge in level and profile using non-woven material is provided for in projects for major and medium track repairs. The repair estimate documentation includes the specified work. The feasibility of use and specific areas for laying non-woven material are established on the basis of operational data on the condition of the track, labor costs for its maintenance, rail output, wear of superstructure elements and other indicators.

Together with the laying of non-woven material, the projects provide for the reconstruction or construction of new drainage systems to ensure the drainage of infiltrated sediments from the non-woven material covering.

1.4. Laying of coverings made of non-woven material is carried out as an independent work or in conjunction with a major (medium) repair of the track, providing for maximum mechanization using track, general construction earth-moving and special machines designed for repairing the roadbed. The work is carried out by track machine stations, including specialized ones, separate specialized columns of these stations and track distance teams.

1.5. The purpose of coverings made of non-woven material should be justified by a technical and economic comparison with other methods of eliminating deformations of the subgrade and strengthening the under-rail base (layout of the main platform, installation of a waterproofing coating, etc.).

1.6. The main characteristics and location of laid non-woven material coverings, as well as changes in the nature and size of deformations after laying, are reflected in the established manner in the relevant forms of technical passports of track distances.

2. INITIAL DATA FOR DESIGN

2.2. During an engineering-geological survey to develop a project to eliminate deformations of the sub-rail base (track subsidence, intense disturbances of the rail track in level and profile on an unstable subgrade, uneven heaving of homogeneous soils), an inspection of the site is carried out, characteristic signs of deformations are recorded and an instrumental survey is carried out. By drilling, digging or testing pits with sampling, the composition, composition and condition of the soils of the subgrade are determined. In this case, at least five points of the under-rail base (along the axis of the track, under both rails on their outer side and at a distance of 20-40 cm from the ends of the sleepers) in the sleeper box and under the sleeper, establish the configuration of the surface of the clay soil on the main area of the roadbed. Determine the presence and depth of groundwater, sources of local soil moisture and other hydrogeological conditions. The required volumes and procedure for conducting engineering-geological surveys are established in accordance with the requirements of the Technical Instructions for eliminating heaves and subsidence of the railway track, TsP/4369.

2.3. Initial data for the design and calculation of coatings using non-woven material in order to eliminate deformations of embankment slopes are obtained in the required volumes in accordance with the requirements of the Temporary Guidelines for calculating the stability of exploited embankments and designing counter-banks (M.: Transport, 1979. 32 pp).

When examining embankments with slope slips, it is advisable to drill exploratory transverse slits along its entire cross-section to delineate the interface between the drainage soils of the ballast layer and the plume and the clayey soils of the embankment along its entire cross-section. The slots are laid in the deformation area and beyond.

2.4. During the engineering-geological examination of deforming slopes of excavations, a geodetic survey of transverse profiles is carried out, the nature of soil bedding in the slope parts, hydrogeological conditions, the size and nature of deformations, as well as the depth of the zone of soil softening under the influence of natural weathering processes are determined, the composition, condition and properties of the soils of each varieties. Soil strength indicators are established in accordance with the requirements of the regulatory and technical document specified in clause 2.3.

2.5. The fastening of flooded slopes is designed on the basis of initial data obtained in accordance with the requirements of the Manual on the survey and design of railway and road bridge crossings over watercourses (TsNIIS, Glavtransproekt. M.: Transport, 1972. 272 p.).

3. CONDITIONS FOR APPLICATION OF NON-WOVEN MATERIALS FOR REINFORCING THE SUB-SITE

3.1. Non-woven material is used to eliminate deformations on operating lines.

Conditions for using nonwoven material depending on the type and causes of deformation during various types roadbed are given in Table 1.

3.2. To strengthen the subgrade, non-woven material is used, which must meet the following requirements:


Strip width, mm
Thickness, mm
Weight 1 m, g
Breaking load, kgf, for a strip 5 cm wide in the direction:
longitudinal
transverse
Elongation at break, %, in the direction:
longitudinal
transverse
Water permeability (filtration coefficient), m/day

3.3. In anti-deformation structures of railway subgrades, it is possible to use a non-woven material that meets the stated requirements and is manufactured according to the technical specifications "Needle-punched fabric for road construction - Dornit. Technical specifications" TU 21-29-81-81*, type 1, which is intended for roads of increased load-bearing capacity . The use of material types 2 and 3 to reinforce railway subgrades is not permitted.
________________
* Specifications mentioned here and further in the text are not given. For more information please follow the link. - Database manufacturer's note.

In addition, it is allowed to use non-woven materials produced according to other technical conditions, including imported ones, if they meet the above requirements, as well as non-woven fabrics used at chemical fiber factories for filtering viscose solutions, washed and sewn into strips.

Test methods for nonwoven material are set out in the specified TU 21-29-81-81.

Table 1. Conditions for the use of nonwoven materials in anti-deformation structures


Type of deformation	Type and elements of the subgrade	Causes of deformation	Anti-deformation measures
A. Elimination of deformations on operating lines
Planting tracks with squeezing liquefied clay soil through the ballast layer during thawing and intense rains; disorders of the rail track in level and profile with the formation of splashes due to the penetration of clay particles from the main platform into the ballast layer		Insufficient bearing capacity of clay soils as a result of increased moistening by infiltrating moisture in the presence of ballast troughs and beds on the main site	Laying a covering of non-woven material over the entire width of the subgrade; when the depth of the ballast beds is more than 0.5 m - laying a covering of non-woven material in combination with a waterproofing film; installation of closed drainages, deepening of ditches and trays below the bottom of ballast beds
Disorders of the rail gauge in level and profile with the formation of splashes as a result of clogging, mainly in the area of joints, leveling spans, turnouts, crossings	Excavations, nullahs and embankments composed of clayey, drainage and rocky soils, tunnels and bridges with ballast running	Insufficient load-bearing capacity of the contaminated ballast layer when moistened by precipitation	Laying a coating of non-woven material within the ballast prism under the rail-sleeper grid
Uneven heaving of the subgrade composed of homogeneous clay soils	Recesses and voids in clayey soils, embankments of clayey soils	High uneven moistening of heaving soils by infiltrating moisture with ballast troughs and beds of different depths on the main site	Laying non-woven material in combination with a waterproofing film over the entire width of the subgrade on top
Slope slips and track settlements on unstable embankments	Embankments of clay soils on a solid foundation	Increased moistening of the upper layers of soil within the main site and slopes by infiltrating moisture, stagnation and accumulation of moisture in ballast depressions on the main site, in cracks and depressions on slopes	Laying non-woven material coverings within the main site and slopes on potentially unstable areas of embankments, including in combination with the installation of counter-banquets; laying a combined coating of non-woven material and waterproofing film on embankments with active manifestation of deformations
Washouts, drifts and slides of excavation slopes	Excavations in homogeneous clayey, as well as in heterogeneous (clayey, draining) soils	Increased soil moisture during thawing and due to infiltrating precipitation, groundwater reaching the surface	Laying a covering of non-woven material on the slope of an excavation with anchoring it at the top in the behind-the-slope part
Destruction of strengthening of flooded slopes, erosion of slopes	Embankments, dams, counter-banquets	Soil removal under the influence of high flow velocities, waves, rise and fall of levels
Erosion of the banks and bottom of watercourses near artificial structures, as well as erosion of the slopes of embankments or cones	Embankments at junctions with artificial structures and at river edges	Water erosion	Laying non-woven material with riprap instead of fascines, mattresses, etc.
Uneven settlement of embankments in swamps	Mounds on swamps	Insufficient bearing capacity of the embankment base	Construction of berms with laying of non-woven material under them
Silting of drainages for various purposes	Drainage systems in excavations, ground zeros and embankments	Mechanical suffusion of soil	Application of non-woven material as a return filter
B. Prevention of deformation
Possible subsidence of the track with the formation of ballast troughs and beds on the main platform, squeezing out liquefied clay soil through the ballast layer	Recesses and voids in clayey soils, embankments of clayey soils	Insufficient bearing capacity of clay soils with a typical ballast prism without a protective layer	Laying non-woven material together with a drainage pad on the main subgrade area
Possible damage to strengthening flooded slopes	Embankments, dams, counter-banquets	Removal and suffusion of soil	Laying non-woven material under the external reinforcement as a return filter

3.4. Parameters for the determination of which there are no regulatory documents are established on non-standard models that take into account the operating mode of non-woven material in railway track structures. These parameters are determined in accordance with the test procedure outlined in the annex.

3.5. When installing a combined coating (see Table 1), a waterproof film is used together with non-woven material, for example, grade B polyvinyl chloride film with a thickness of 0.23 mm (GOST 16272-79).

The film used must have the following characteristics:


Width, mm
Thickness, mm
Breaking tensile stress, kgf/cm
Elongation at break, %
Vapor permeability in 24 hours, g/m
Brittleness temperature, °C

4. ELIMINATION OF TRACK SETTLEMENTS AND RAIL TRACK DISORDERS ON UNSTABLE AREAS OF THE SUBSTRATE.

4.1. To eliminate track subsidence and disorders of the rail track in level and profile, a non-woven material coating is laid on unstable sections of the subgrade when the depth of ballast troughs and beds is less than 0.5 m. The design of this coating in cross section on single-track and double-track sections of railways is shown in Fig. 1 and 2.

Fig.1. Schemes for laying a coating of non-woven material to eliminate track subsidence and rail track disorders in level and profile on unstable sections of the roadbed within embankments

Fig.1. Schemes for laying a coating of non-woven material to eliminate track subsidence and rail track disorders in level and profile on unstable sections of the roadbed within embankments:

A- on a single-track line; b, c 1 - non-woven material; 2 - ballast; 3 - clay soils

Fig.2. Schemes for laying a coating of non-woven material to eliminate track subsidence and disorders of the rail track in level and profile on unstable sections of the roadbed in excavations

Fig.2. Schemes for laying a coating of non-woven material to eliminate track subsidence and disorders of the rail track in level and profile on unstable sections of the roadbed in excavations:

A- on a single-track line; b, c- on a double-track line with one track and two tracks; 1 - non-woven material; 2 - ballast; 3 - clay soils; 4 - drainage; 5 - tray

The non-woven material is placed at a depth of at least 0.2 m below the bottom of the sleepers () on the surface of ballast materials cut and leveled with a slope of at least 0.04 to the field side.

If the distance from the top of the ballast prism to the main platform of the subgrade made of sandy loam and loam with a yield boundary is less than 0.7 m along the axis of the track, and for heavier loams and clays - less than 1 m, then after laying the non-woven material covering, an additional lift is made ways to achieve the specified values.

The covering is laid across the entire width of the subgrade on top. On double-track sections, in the absence of deformations on the adjacent track, it is possible to install covering only on one track.

The bottom of ditches, trays, closed drainages in recesses and zero places should be located 0.2 m below the coating and 0.15 m below the bottom of the ballast beds. If these conditions are not met, the drainage systems are rebuilt, lowering the level of their bottom.

To eliminate track subsidence and track disturbances under turnouts, the coating must be of variable width. The edges of the covering are located behind the ends of the transfer bars by at least 0.9 m (Fig. 3, A). It is laid 0.2 m below the bottom of the beams with a slope of at least 0.02.

Fig. 3. Diagram of a non-woven material coating for eliminating track subsidence

Fig. 3. Diagram of a non-woven material coating for eliminating track subsidence:

A- on turnouts; b- on station tracks; 1 - non-woven material; 2 - drainage; 3 - ballast; 4 - clay soils

When constructing a covering under turnouts and on station tracks, a shallow drainage with a longitudinal slope of at least 0.03 is laid along it between the tracks, the outlet from which is carried out by transverse drainage (see Fig. 3, a, b). To do this, use pipe filters or a “blind” drain with a diameter of at least 15 cm, which is made of crushed stone wrapped in non-woven material. The bottom of the drainage should be below the edge of the covering.

In the same way, if necessary, water is drained from between tracks on stretches in curved sections of the track.

When using crushed stone of normal size in the ballast layer, a layer of sand, asbestos ballast or small crushed stone of a fraction of 10-25 mm with a thickness of 5-10 cm is laid on the non-woven material.

When eliminating track subsidence, separate strips of nonwoven material in the coating are placed across the track, i.e. the length of these strips should be equal to the width of the coating. The strips must overlap each other by at least 0.2 m. When eliminating disorders of the rail gauge in level and profile on unstable sections of the roadbed, it is allowed to place strips of non-woven material along the track with a mutual overlap of at least 0.2 m.

In difficult engineering-geological conditions with intense track subsidence with squeezing out liquefied soil through ballast, non-woven material in the coating can be laid in two layers. In this case, crushed stone of normal size can be directly laid on non-woven material.

The section covered with non-woven material must cover the length of the section of the track with apparent deformations by at least 30 m on each side. The minimum length of the covered section can be 30 m.

It is not allowed to lay a covering of non-woven material to eliminate track subsidence and disorders of the rail track in level and profile on unstable sections of the subgrade only within the rail joints.

4.2. To eliminate those considered in at this point track deformations in areas where the depth of ballast troughs and beds on the main platform of the roadbed is more than 0.5 m, a combined coating of non-woven material and waterproofing film should be used. The film is placed between two layers of nonwoven material (Fig. 4).

Fig.4. Diagram of the installation of a combined coating of non-woven material and waterproofing film when eliminating track subsidence

Fig.4. Diagram of the installation of a combined coating of non-woven material and waterproofing film to eliminate track subsidence:

1 - non-woven material; 2 - waterproofing film; 3 - new ballast; 4 - uncut ballast; 5 - clay soil

The covering is placed at a depth of at least 0.3 m from the bottom of sleepers or transfer bars (when laid under turnouts).

Crushed stone of normal size can be laid directly on the combined coating.

Strips of non-woven material and waterproofing film are spread along the path, starting from the bottom side, which ensures water drainage from the coating in the transverse direction.

The remaining requirements for the installation of the coating are observed in accordance with clause 4.1.

5. ELIMINATION OF DISORDERS OF THE RAIL GAUGE AT THE LEVEL AND IN THE PROFILE WITH THE FORMATION OF SPLASHES IN CLOGGED AREAS

5.1. Non-woven material is placed within the ballast prism at a depth of at least 20 cm from the bottom of the sleepers (Fig. 5, A).

Fig.5. Schemes for the design of a coating made of non-woven material when eliminating disorders of the rail gauge in level and profile in areas with splashes from clogging

Fig.5. Schemes for the design of a coating made of non-woven material when eliminating disorders of the rail gauge in level and profile in areas with splashes from clogging:

A- on hauls; b- within turnouts; 1 - cleaned ballast layer; 2 - non-woven material; 3 - the ballast layer is contaminated; 4 -drainage

Under the layer of non-woven material, the crushed stone must be cleared of debris to a depth of at least 10 cm in order to ensure the most complete and rapid removal of infiltrating moisture into this layer. Laying non-woven material on unplanned rollers of cleaned crushed stone in under-rail sections remaining after the operation of the ballast cleaning machine is not allowed. This surface must be level.

When using crushed stone of normal size in the ballast layer, a layer of fine crushed stone or sand 5-10 cm thick is poured onto the non-woven material. This layer can be omitted if the non-woven material in the coating is laid in two layers: placement of the second layer is allowed within the under-rail sections of the width at least 0.8 m under each of them (for example, by appropriately overlapping two lanes in these places).

5.2. The operation of straightening and tamping machines during the laying of the coating until a layer of ballast 20 cm thick is created under the sole of the sleepers is not allowed, since in this case the coating will be torn apart (VPR) or collected under the rail-sleeper grid (RSO).

5.3. The accumulation of clogging above the layer of non-woven material will occur in the usual way, however, the drainage conditions in this case are more favorable, since the path and time of moisture filtration will be reduced compared to conventional design ballast prism without non-woven material. Rapid drainage of water down and to the side will prevent weeds from becoming waterlogged, which increases the load-bearing capacity of the ballast layer.

Non-woven material is laid under the rail-sleeper grid to a width of at least 4.5 m. Within the turnouts, the width of this covering should be variable and exceed the length of the transfer bars by m on each side (Fig. 5, b).

In areas with a stable subgrade, where disturbances in the rail gauge in level and profile with the formation of splashes occur due to weeds, a continuous covering is installed; at the same time, in some justified cases, it is allowed to construct a covering only under joints, and in sections of continuous track - under leveling spans. On turnouts, it is allowed to lay material in the areas of the crosspiece and frame rail that are most susceptible to dynamic effects from moving loads. The edges of the covering must be at least 2 m from the joints.

To drain water in the transverse direction, the layer of non-woven material is brought up to the slope of the ballast prism on hauls, and on station tracks and turnouts - to shallow drainage. This drainage is arranged in accordance with the requirements of clause 4.1.

5.4. The coating within the abutments of bridges, as well as the spans of reinforced concrete bridges running on ballast, is laid at the depth indicated above, reaching the sides of the ballast troughs (reverse walls of the abutments). Longitudinal drainage of water is carried out using drains, which are placed along these sides. In this case, drains can be made of non-woven material, which is rolled into a roll from a strip approximately 1 m wide.

6. APPLICATION OF COATING FROM NON-WOVEN MATERIAL AND WATERPROOFING FILM TO ELIMINATE HEAVENS

6.1. The conditions for using this coating are set out in Table 1. Uneven heaving in homogeneous soils manifests itself in this case as a result of the existing (or ongoing) subsidence of the track. The ballast troughs and beds of varying depths that arise during these subsidences lead to increased uneven moistening of cohesive soils that are infiltrated with moisture. Due to its properties, non-woven material cannot be used independently to eliminate heaves. It is used for this purpose in conjunction with a waterproofing film, which retains infiltrating precipitation.

6.2. The construction of a coating made of non-woven material and a waterproofing film to eliminate heaving under the conditions under consideration is carried out in accordance with the requirements set out in clause 4.2.

7. ELIMINATION OF SLOPE SLIDDS AND PATH SETTLEMENT ON UNSTABLE EMBARKES ON A SOLID FOUNDATION

7.2. A coating made of non-woven material can be used if the embankment slopes do not slide, but the following signs of deformation appear:

precipitation, including one-way precipitation, and shifts of the rail track, usually associated with the period of ground thawing and intense rains;

cracks at the ends of the sleepers, on the sides and slopes;

subsidence of roadsides, soil uplifts on slopes;

change in steepness and outline of slopes.

The use of such a coating is most appropriate for increasing the stability of the embankment in its upper part, which has a height (counting from the top) of 6-8 m, with a thickness of the potentially unstable soil mass on the slope up to 1.5-2 m. In this part of the embankment, they are usually located , unstable ballast trains and it is usually not possible to ensure its stability by filling counter-banquets.

7.3. The covering consists of a non-woven material laid over the surface of the slope and a layer of drainage soil poured on top. The non-woven material is anchored in the upper part outside the potentially unstable mass, placing it in a ballast prism under the rail-sleeper grid. Under these conditions, the joint work of the nonwoven material and the soil is ensured due to the forces of friction and adhesion between them. Shearing forces, which are an integral part of gravity, in the presence of a coating must overcome not only those holding forces that develop on the surface of possible displacement (friction and adhesion forces), but also the tear resistance of the interlayer. The pavement parameters that ensure the stability of the embankment with a given coefficient are determined by calculation. In this case, three conditions must be met simultaneously: sufficient adhesion of the nonwoven material to the underlying soil; tensile strength of the material; reliability of anchoring in the upper part.
[email protected]

If the payment procedure on the payment system website has not been completed, monetary
funds will NOT be debited from your account and we will not receive payment confirmation.
In this case, you can repeat the purchase of the document using the button on the right.

An error has occurred

The payment was not completed due to a technical error, cash from your account
were not written off. Try waiting a few minutes and repeating the payment again.

Non-woven synthetic material (NSM) is a non-woven needle-punched fabric, which is made by weaving synthetic polymer fiber. It is not subject to wear and rot. Due to the combination of excellent indicators, the material is convenient to use in most areas of human activity: construction works, road construction, pipeline laying, agriculture, design and more.

The NSM is capable of performing four functions at once:

Filtration. Due to its unique structure, the canvas prevents the passage of sand and earth particles into the pores of the material, preventing the possibility of silting;
Drainage. Prompt drainage of water is ensured, which increases the performance of the drainage system;
Reinforcing. Like a geogrid, it takes on the soil load and can partially withstand tensile stress;
Dividing. NSM serves separating layer, eliminating mixing of the top layer and base. At the same time, the thickness of the top layer does not change.

Advantages of the material

NSM is widely popular today due to:

Durability;
Environmental friendliness. The canvas is not affected chemical elements, thanks to which harm to people and nature can be avoided;
Strength. The material has high level resistance to mechanical stress and puncture. Tensile threads allow the web to be lengthened, which eliminates the possibility of damage during installation;
Impact resistance natural factors. Does not cause debate, siltation and does not rot. Resistant to ultraviolet rays, exposure to acids, alkalis and organic matter. The material is not affected in any way by fungi and bacteria;
Ease of installation. NSM is supplied in the form of easy-to-transport rolls, which, if necessary, can be cut into two parts using an ordinary saw. hand saw. The material can also be cut with scissors and a knife;
Economical. With all its advantages, NSM is relatively inexpensive, which is the main reason for its use in many areas of life.

Areas of use

Is a filter in drainage systems;
Men at work. Used for laying railway tracks, highways. It is assigned a reinforcing function; Can also be used for garden paths.
Agriculture. NSM material can protect crops from weeds, and the soil from contamination by microorganisms and drying out.
In construction. Used as waterproofing layer and a protective layer in the roof and foundation;
Strengthening the banks and slopes of reservoirs;

NSM characteristics table

. Scope and effectiveness of the card

INTRODUCTION

1. GENERAL PROVISIONS

2. INITIAL DATA FOR DESIGN

3. CONDITIONS FOR APPLICATION OF NON-WOVEN MATERIALS FOR REINFORCING THE SUB-SITE

4. ELIMINATION OF TRACK SETTLEMENTS AND RAIL TRACK DISORDERS ON UNSTABLE AREAS OF THE SUBSTRATE.

Fig.1. Schemes for laying a coating of non-woven material to eliminate track subsidence and rail track disorders in level and profile on unstable sections of the roadbed within embankments

Fig.2. Schemes for laying a coating of non-woven material to eliminate track subsidence and disorders of the rail track in level and profile on unstable sections of the roadbed in excavations

Fig. 3. Diagram of a non-woven material coating for eliminating track subsidence

Fig.4. Diagram of the installation of a combined coating of non-woven material and waterproofing film when eliminating track subsidence

5. ELIMINATION OF DISORDERS OF THE RAIL GAUGE AT THE LEVEL AND IN THE PROFILE WITH THE FORMATION OF SPLASHES IN CLOGGED AREAS

Fig.5. Schemes for the design of a coating made of non-woven material when eliminating disorders of the rail gauge in level and profile in areas with splashes from clogging

6. APPLICATION OF COATING FROM NON-WOVEN MATERIAL AND WATERPROOFING FILM TO ELIMINATE HEAVENS

7. ELIMINATION OF SLOPE SLIDDS AND PATH SETTLEMENT ON UNSTABLE EMBARKES ON A SOLID FOUNDATION

Read also