RU2389931C1 - Method for soil reinforcement in area of pipeline installation - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method for reinforcement of soil in area of pipeline installation includes formation of trench, having shape of isosceles trapezoid in cross section, placed with smaller base down, by excavation of subsiding soil to a designed depth, laying of flexible mat, its fixation by anchors and filling of trench, at that soil is excavated to the depth of at least 0.5 metre below the level of pipeline foot, width of trapezoid lower base makes at least 0.5 metre, distance between trapezoid ribs at the level of pipeline foot makes at least four radiuses of pipeline, angle of trench slope location should make not more than 45 degrees, and after formation of trench soil is laid in layers to the level of pipeline foot with compaction of each layer to a specified module of elasticity, then flexible mat is laid onto compacted bottom and walls of trench, and flexible mat is arranged in the form of geogrid from glass fibre with overlap of at least 0.30 m and rupture strength of not less than 30 kH/m. Fixation of geogrid from glass fiber with anchors is done on both sides of upper base of formed trench. Trench is filled so that height of soil over upper point of pipeline makes at least 0.2 metre and not more than 0.3 metre from upper point of pipeline to earth surface. Afterwards glass fiber geogrid with rupture strength of at least 30 kH/m² is laid onto soil surface, and final soil is filled to the level of earth surface.

EFFECT: reinforcement of soil making it possible to tightly fix pipeline in the area of its installation with simultaneous reduction of stretching forces effect at pipeline.

3 cl, 1 dwg

Description

The invention relates to construction and can be used for laying or repairing pipelines in soft soils.

There is a method of strengthening weak soils, which consists in laying the geogrid on the ground with tension, fixing it on the ground, followed by filling the geogrid cells with bulk material, while the geogrid is made in the form of a set of mechanically strong flexible tapes, and the grid cells have the shape of hexagons. Strengthening slopes with a steepness of more than 45 degrees begin from the bottom of the slope and each subsequent layer is laid with a shift towards the slope (RU 2228479, 05/10/2004).

The known method is expensive and not quite suitable for reinforcing the soil located at the site of the pipeline.

A known method of strengthening the soil, which includes laying geotextile material on the bottom and walls of the trench, laying in the trench of the pipeline, dusting powder material around it, wrapping the geotextile material around the powder layer and filling the soil in the trench (RU 2183233, 06/10/2002).

However, to implement this method, you need a special device for laying geotextile material on top of the bulk material, which increases the cost of work.

Closest to the proposed technical solution is a method of strengthening the soil when laying a pipeline, which includes the formation of a trench, by sampling the subsidence soil to the estimated depth. The formed trench has the cross section in the form of an isosceles trapezoid placed with a smaller base down. Then, a flexible carpet with symmetrical deflections is laid in the trench over the pipeline and along the bottom of the trench. Fasten the carpet with anchors and fill the trench with ensuring the fit of the carpet to the bottom of the pits and trenches (RU 2274793, 04.20.2006).

The disadvantage of this method is the loose fixation of the pipeline in the ground.

The present invention is to develop a method of strengthening the soil, allowing you to tightly fix the pipeline in place of its laying while reducing the effect of tensile stresses on the pipeline.

The problem is solved by the claimed method of strengthening the soil at the site of the pipeline, which includes the formation of a trench having a cross-sectional shape of an isosceles trapezoid placed with a smaller base down by sampling the subsiding soil to the calculated depth, laying a flexible carpet, fixing it with anchors and filling the trench. In this case, the soil is chosen to a depth of at least 0.5 meters below the level of the sole of the pipeline. The width of the lower base of the trapezoid is at least 0.5 meters, the distance between the edges of the trapezoid at the level of the bottom of the pipeline is at least four radii of the pipeline. The angle of the slope of the trench should be no more than 45 degrees. After the formation of the trench, layer-by-layer soil filling is carried out to the level of the sole of the pipeline with the compaction of each layer to a given modulus of elasticity. Then, a flexible carpet made in the form of a fiberglass geogrid with an overlap of at least 0.30 m and a tensile strength of at least 30 kN / m ^{2 is} laid on the sealed bottom and on the walls of the trench. Fiberglass geogrids are anchored with anchors on both sides of the upper base of the formed trench. The trench is filled so that the height of the soil above the top point of the pipeline is at least 0.2 m and not more than 0.3 m from the top point of the pipeline to the surface of the earth. After that, a fiberglass geogrid with a tensile strength of at least 30 kN / m ^{2 is} laid on the soil surface and the soil is finally filled to the ground surface level.

Preferably, the anchors for securing the geogrid are installed outside the formed trench at a distance of 0.2-0.4 m from each edge of the upper base.

Before filling the trench, the pipeline may be covered with a fiberglass reinforcing mesh with a tensile strength of at least 30 kN / m ² .

It should be noted that the proposed method can be used both when laying new pipelines, and when reconstructing or repairing previously constructed facilities, while it is suitable for laying pipelines with a diameter of up to 1420 mm.

The implementation of the invention is illustrated in the drawing, which shows a cross section of the trench at the site of the pipeline, where 1 is the pipeline, 2 is the reinforcing mesh, 3 is the geogrid, 4 is the subsidence soil, 5 is the soil used when filling, 6 is the anchor, 7 is the level the bottom of the pipeline, α is the angle of the slope of the trench, b ₁ is the width of the anchor, b ₂ is the width of the lower base of the trench, h ₁ is the distance from the lower base of the trench to the level of the bottom of the pipeline, h ₂ is the height of the soil above the upper point of the pipeline, h ₃ - distance from the top of the pipeline to the surface of the earth.

The claimed method is as follows.

Example 1

For a pipe diameter of 1420 mm, a trench is formed in the form of an isosceles trapezoid placed with a smaller base down. Select subsidence soil to a depth of at least 1520 mm. The width of the lower base of the trapezoid is at least 0.5 m. The width of the base of the trench at the bottom of the pipeline is at least 2.85 m. When laying the slope of the trench 45 °, the width along the top will be 5.70 m.

After the formation of the trench, the pipeline is laid and layer-by-layer soil filling is carried out to the level of the sole of the pipeline with the compaction of each layer to a given modulus of elasticity. Then, a fiberglass geogrid with an overlap of at least 0.30 m and a tensile strength of at least 30 kN / m ^{2 is} laid on the bottom and walls of the trench. Then, from two sides at a distance of 0.2-0.4 m from each edge of the upper base of the formed trench, fiberglass geogrids are anchored. The pipeline is coated with a fiberglass reinforcing mesh with a tensile strength of at least 30 kN / m ² .

Fill the trench so that the height of the soil above the top point of the pipeline is at least 0.2 m and not more than 0.3 m from the top point of the pipeline to the surface of the earth. After that, a fiberglass geogrid with a tensile strength of at least 30 kN / m ^{2 is} laid on the soil surface and the soil is finally filled to the ground surface level.

Example 2

For a pipe diameter of 620 mm, a trench is formed in the form of an isosceles trapezoid placed with a smaller base down. Select subsidence soil to a depth of at least 720 mm. The width of the lower base of the trapezoid is at least 0.5 m. The width of the base of the trench at the bottom of the pipeline is at least 1.25 m. When the slope of the trench is laid at 33.7 ° (in the formula, the slope is not more than 45 °), the width at the top will be 3, 10 m

After the formation of the trench, the pipeline is laid and layer-by-layer soil filling is carried out to the level of the sole of the pipeline with the compaction of each layer to a given modulus of elasticity. Then, a fiberglass geogrid with an overlap of at least 0.30 m and a tensile strength of at least 30 kN / m ^{2 is} laid on the bottom and walls of the trench. Then, from two sides at a distance of 0.2-0.4 m from each edge of the upper base of the formed trench, fiberglass geogrids are anchored. The pipeline is coated with a fiberglass reinforcing mesh with a tensile strength of at least 30 kN / m ² . Fill the trench so that the height of the soil above the top point of the pipeline is at least 0.2 m and not more than 0.3 m from the top point of the pipeline to the surface of the earth. After that, a fiberglass geogrid with a tensile strength of at least 30 kN / m ^{2 is} laid on the soil surface and the soil is finally filled to the ground surface level.

When using the claimed method, the following advantages are achieved:

- reduction of the deflection of the pipeline in the longitudinal direction,

- prevention of soil erosion around the pipeline in areas with prolonged slopes,

- reduction of soil displacement around the pipeline.

Claims (3)

1. A method of reinforcing the soil at the site of the pipeline, including the formation of a trench having an isosceles trapezoid in cross section, placed smaller base down, by sampling the subsidence soil to the calculated depth, laying a flexible carpet, fixing it with anchors and backfilling the trench, characterized in that the soil choose to a depth of at least 0.5 m below the level of the bottom of the pipeline, while the width of the lower base of the trapezoid is at least 0.5 m, the distance between the ribs of the trapezoid at the level of the bottom of the pipeline is t of at least four pipeline radii, and the trench's slope angle should be no more than 45 °, after the formation of the trench, lay the pipeline and layer-by-layer soil filling to the level of the bottom of the pipeline with compaction of each layer, then a fiberglass overlap geogrid is laid on the bottom and walls of the trench not less than 0.30 m and a tensile strength of not less than 30 kN / m ^2, consolidation is carried geogrid fiberglass anchors on both sides of the upper base formed trench, backfilling the trench so produced to Height of the soil over the top point of the pipeline is not less than 0.2 m and not more than 0.3 m from the top of the pipeline to the surface, and then placed on the soil surface geogrid fiberglass with a tensile strength of at least 30 kN / m ² and produce final filling with soil to the level of the earth's surface. 2. The method according to claim 1, characterized in that the anchors for securing the geogrid are installed outside the formed trench at a distance of 0.2-0.4 m from each edge of the upper base. 3. The method according to claim 1, characterized in that the pipeline before filling the trenches is covered with a reinforcing mesh of fiberglass with a tensile strength of at least 30 kN / m ² .

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