A geogrid steep slope embankment structure and construction method

Abstract

The present invention discloses a geogrid steep slope embankment structure with a backpacking type, wherein a plurality of geogrid backpacking layers are stacked up and down at the free surface of the slope, a thick gravel cushion adjustment layer and a grid prefabricated block are sequentially laid on the outside of the geogrid backpacking layer, and pebbles are filled in the grid prefabricated block; each geogrid backpacking layer includes a geogrid, the cross section of which is a trapezoidal groove structure with one side open, the closed end of the geogrid is located at the free surface of the slope, the end of the geogrid is fixed to the roadbed, a geotextile is laid on the inner wall of the geogrid, and the geotextile is filled with gravel soil roadbed filler. The present invention solves the problem that the soil near the free surface is difficult to compact and the grid tensioning is labor-intensive and time-consuming during the laying of the geogrid through a geogrid reinforced soil structure that is more conducive to giving full play to the reinforcement performance of the geogrid, thereby improving the stability of the reinforced steep slope embankment, and a matching construction process.

Description

Technical Field

[0001] The invention belongs to the technical field of embankment filling, and in particular relates to a geogrid steep slope embankment structure with automatic tensioning grid and a construction method. Background Art

[0002] In the process of building mountain roads, if the ground slope is steep, the conventional large slope foot design cannot be used. Usually, masonry structure is used to shrink the slope foot. The use of geogrid reinforced steep slope embankment can replace the masonry structure, significantly reducing the construction difficulty of the project, shortening the construction period, reducing the project cost, and speeding up the progress of the project. However, at home and abroad, the construction of geogrid reinforced steep slope embankment on the free surface adopts the method of stacking vegetation bags on the free surface as temporary support. The disadvantage of this method is that it is not suitable for arid areas where vegetation is difficult to grow on the slope, and the fill in the bag is still difficult to compact, the grid tensioning needs to be tensioned separately, and the labor cost is extremely high. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies in the prior art and provide a geogrid steep slope embankment structure and construction method to solve the problem of geogrid-gravel soil reinforced steep slope embankment free surface construction and grid tensioning integrated construction.

[0004] The present invention is achieved through the following technical solutions:

[0005] A geogrid steep slope embankment structure with a backpacking type is provided, in which a plurality of geogrid layers are stacked from bottom to top on the free surface of the slope, a thick gravel cushion adjustment layer and a grid prefabricated block are laid in sequence on the outer side of the geogrid layer, and pebbles are filled in the grid prefabricated blocks;

[0006] Each layer of the geogrid wrapping layer includes a geogrid used to wrap the gravel roadbed filler. The cross-section of the geogrid is a trapezoidal trough structure with one side open. The closed end of the geogrid is located on the free side of the slope. The end of the geogrid is fixed to the roadbed. The inner wall of the geogrid is paved with geotextile, and the geotextile is filled with gravel roadbed filler.

[0007] Preferably, a shallow arc groove is provided on the top surface of each layer of the back-wrapped geogrid layer, and the adjacent geogrid is in contact with the shallow arc groove and is in a tensioned state.

[0008] Preferably, the shallow arc-shaped groove has a width of 1 m and a depth of less than 20 cm.

[0009] Preferably, the height of the returned geogrid layer is 50 cm.

[0010] Preferably, the embankment slope is gentler than any slope of 1:0.5.

[0011] The present invention also provides a construction method of a geogrid steep slope embankment structure, comprising the following steps:

[0012] Step 1: Draw the slope edge line and the laying edge line of the geogrid inside the slope on the steps of the embankment, and excavate a shallow arc groove in the anchoring section of the geogrid;

[0013] Step 2: Lay the geogrid along the laying edge line of the geogrid inside the slope, place the geogrid of the return section outside the edge line of the slope, and tighten the geogrid to fix it to the roadbed;

[0014] Step 3, laying geotextile on the geogrid in step 2, the geotextile is fixedly connected to the geogrid, and the return section of the geotextile is placed outside the edge line of the slope;

[0015] Step 4: Fill the gravel roadbed filler on the geogrid until the top of the roadbed filler is paved and then roll it. After rolling, the geogrid is tightly attached to the shallow arc groove, and then the slope is processed according to the designed slope rate;

[0016] Step 5, the geotextile and geogrid of the backpacking section are backpacked upward along the slope to the top surface of the compacted roadbed fill to form a backpacking geogrid layer;

[0017] Step 6, repeat steps 1-5 on the backpack geogrid layer, construct layer by layer to the designed number of layers, and the backpack geogrid of the lower layer is fixedly connected to the geogrid of the upper layer;

[0018] Step 7: After the construction reaches the designed number of layers, cast-in-place concrete capping and pavement structure layer on top of the top geogrid layer, and lay gravel cushion adjustment layer and grid precast blocks in sequence on the outside of the geogrid layer, and fill the grid precast blocks with pebbles.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] The present invention stacks a plurality of geogrid layers from bottom to top on the free surface of the slope, and each geogrid layer uses a geotextile and geogrid to wrap the loose gravel soil roadbed filler, and then connects the lower geogrid with the upper geogrid by a connecting rod, so that the upper and lower geogrids form a semi-closed annular geogrid layer on the free surface of the slope, which has a lateral restraint effect on the soil.

[0021] At the same time, under the action of the load of the upper covering soil, the gravel soil roadbed filler in the backpack geogrid layer generates outward tension during the compaction process, which causes the geogrid on the free side of the slope to generate outward tension, thereby causing the geogrid to generate pre-tensioning force, giving full play to the high-strength characteristics of the geogrid, which can effectively improve the stability of the slope. During the rolling process of the upper soil, the tension generated by the geogrid in the backpack section of the slope maximizes the reinforcement effect of the geogrid, thereby reducing the deformation inside the reinforced steep slope roadbed.

[0022] The present invention increases the volume of the semi-enclosed geogrid layer at the free surface of the steep slope embankment. During the roadbed filling process, the gravel soil roadbed filling inside is compressed by the dual effects of the deadweight load of the soil above the geogrid layer and the lateral restraint force of the geogrid layer on the internal gravel soil roadbed filling, thereby increasing the compaction degree of the soil at the free surface of the slope, eliminating the rolling of the soil at the edge of the free surface, solving the problem that the soil at the free surface is difficult to compact, reducing the construction cost, shortening the construction period, and achieving the desired effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the steep slope embankment structure of the present invention;

[0024] Figure 2 This is the schematic diagram of laying the first layer of geogrid;

[0025] Figure 3 This is the schematic diagram of the first layer of geogrid return package;

[0026] Figure 4 This is the schematic diagram for laying the second layer of geogrid;

[0027] Figure 5 This is a schematic diagram of the structure of the grid prefabricated block.

[0028] In the figure: In the figure: 1—geogrid, 2—geogrid of the return section, 3—geotextile of the return section, 4—designed slope rate of the slope, 5—edge of the steep embankment slope, 6—the part of the roadbed edge that cannot be compacted, 7—the virtual top surface of the roadbed fill, 8—the top surface of the roadbed fill after compaction, 9—the rolling edge line, 10—the excavation part of the shallow arc groove, 11—the shallow arc groove, 12—the laying edge line of the geogrid inside the slope, 13—the edge line of the slope, 14—connecting rods, 15—gravel cushion adjustment layer, 16—grid prefabricated blocks, 17—pebbles, 18—cast-in-place concrete top, 19—pavement structure layer, 20—gravel roadbed filler, 21—anchor rods, 22—U-shaped nails. DETAILED DESCRIPTION

[0029] The present invention will be further described in detail below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0030] like Figure 1 As shown, the present invention provides a geogrid steep slope embankment structure, the embankment slope is gentler than any slope of 1:0.5, a plurality of geogrid layers are stacked up and down on the free surface of the slope, a thick gravel cushion adjustment layer 15 and a grid prefabricated block 16 are sequentially laid on the outer side of the geogrid layer, and pebbles 17 are filled in the grid prefabricated block 16;

[0031] Each layer of the back-wrapped geogrid layer includes a geogrid 1, the cross section of which in the working state is a trapezoidal groove structure with one side open, the closed end of the geogrid 1 is located on the free side of the slope, the inner wall of the geogrid 1 is paved with a geotextile, and the geotextile is filled with gravel roadbed filler. A shallow arc groove 11 is set on the top surface of each layer of the back-wrapped geogrid layer, and the adjacent geogrid 1 is in contact with the shallow arc groove 11 and is in a tensioned state.

[0032] The height of the geogrid layer in the backpacking section is 50cm. The end of the geogrid 1 is fixed on the roadbed with a U-shaped nail 22. After the geogrid 1 is laid, the embankment is rolled. After rolling, the geogrid 1 is close to the shallow arc groove 11 with a width of 100cm and a maximum depth of 20cm. The geogrid 1 is tensilely deformed along the shallow arc groove 11, so that the geogrid 1 plays an automatic tensioning role. The slope surface uses the backpacking section geotextile 3 and the backpacking section geogrid 2 to backpack in sequence, and at the same time, they work together with the shallow arc groove 11 to give full play to the tensile strength of the geogrid 1. A 15cm thick gravel cushion adjustment layer 15 is laid on the slope surface, and the square grid prefabricated blocks 16 and pebbles 17 are laid on the gravel cushion adjustment layer 15 to fill the gaps to form a flexible slope protection system suitable for arid areas.

[0033] The present invention stacks multiple layers of backpack geogrid layers on the free surface of the slope, uses backpack geotextile and backpack geogrid in each layer to wrap loose gravel soil roadbed filler, and then connects the lower backpack geogrid 2 with the upper geogrid 1 by connecting rods 14, so that the upper and lower geogrids form a semi-closed annular enclosure at the free surface of the slope that has a lateral restraint effect on the soil, namely, the backpack geogrid layer.

[0034] At the same time, during the construction of the steep slope embankment, the semi-enclosed return geogrid layer is compacted downward by the overlying soil load, so that the return geogrid generates outward tension at the free surface of the slope, thereby pre-stressing the geogrid, giving full play to the high-strength characteristics of the geogrid, and effectively improving the stability of the slope. During the rolling process of the upper soil, the tension generated by the return geogrid 2 on the slope surface maximizes the reinforcement effect of the geogrid, thereby reducing the deformation inside the reinforced steep slope roadbed.

[0035] The present invention increases the volume of the semi-enclosed geogrid layer at the free surface of the steep slope embankment. During the roadbed filling process, the internal soil is compressed by the dual effects of the deadweight load of the soil above the geogrid layer and the lateral restraint force of the geogrid layer on the internal soil, thereby increasing the compaction degree of the soil at the free surface of the slope, eliminating the need for rolling of the soil at the edge of the free surface, solving the problem of difficult compaction of the soil on the free surface, reducing the construction cost, shortening the construction period, and achieving the desired effect.

[0036] like Figure 2-5 As shown, the present invention provides a construction method for a geogrid steep slope embankment structure, comprising the following steps:

[0037] Step 1: Clean the humus, topsoil, and turf on the original ground surface in accordance with the requirements of the "Technical Specifications for Highway Roadbed Construction". First, according to the position and elevation of each step marked in the design drawing, the original ground is excavated according to the overall arrangement of the steps in the plane and longitudinal plane to ensure that the steps of the same layer are excavated as a whole. The minimum width of the steps shall not be less than 2.5m, and the steps shall be built into a 4.5% inward slope, and then the steps shall be compacted, with a compaction degree of not less than 92%.

[0038] Step 2: Draw the position of the slope edge line 13 and the laying edge line 12 of the geogrid inside the slope according to the design drawing, and sprinkle lime as a mark. The laying edge line 12 of the geogrid inside the slope to 2m in the direction of the free surface is the anchoring section of the geogrid 1. Dig a shallow arc groove 11 in the anchoring section, dig out the excavated part 10 of the shallow arc groove, and remove the loose blocks in the shallow arc groove 11 and sharp objects that may damage the geogrid 1.

[0039] Step 3: lay the first layer of geogrid 1 on the lowest step according to the design elevation. The cutting length of geogrid 1 is the laying length, slope length and return length of geogrid 1 in the design drawing. When laying, the return section of geogrid 1, geogrid 2, is placed vertically outside the slope edge line 13.

[0040] The return section geogrid 2 includes the slope length and the return length on the top of the gravel soil roadbed filling.

[0041] Step 4: Using the slope edge line 13 as the control line, lay the cut geotextile on the geogrid 1, and place the geotextile return section vertically outside the slope edge line 13;

[0042] The width of the geotextile within the slope edge line 13 and the geotextile returned on the top of the gravel roadbed filler shall not be less than 0.5m. Use U-shaped nails 22 to fix the geotextile 3 and geogrid 1 of the returned section with U-shaped nails 22 30cm inside the edge line of the free surface. After the geogrid is flattened and tightened, fix the transverse ribs of the geogrid 1 on the inside of the laying edge line 12 of the geogrid inside the slope to the roadbed with U-shaped nails 22.

[0043] Step 5, filling gravel roadbed filler 20 on the laid geogrid 1, filling to the roadbed fill virtual top surface 7 and then mechanically rolling, compacting the rest of the area except the uncompacted part 6 at the edge of the roadbed to form a compacted roadbed fill top surface 8, and the geogrid 1 after rolling is close to the shallow arc groove 11, and the tensile deformation of the geogrid 1 has a tensioning effect on the geogrid 1, and at the same time, a certain mutual displacement is generated between the fill and the geogrid 1 during the rolling process, which promotes the embedding between the grid mesh and the soil particles, and can effectively utilize the high strength performance of the geogrid to give full play to the reinforcement effect of the geogrid in gravel soil.

[0044] Step 6: After rolling, the steep embankment slope edge 5 and the uncompacted portion 6 of the roadbed edge are artificially repaired according to the slope design slope rate 4.

[0045] Step 7, re-wrap the geotextile 3 reserved for the return section outside the slope edge line 13, fix it on the top surface 8 of the roadbed fill with U-shaped nails 22, and re-wrap the reserved return geogrid 1 along the artificial slope repaired slope to the top surface 8 of the roadbed fill, and then lay the upper layer of geogrid 1, and connect the newly laid upper layer of geogrid 1 with the return section geogrid 2 of the lower layer with connecting rods 14 to form a complete slope return body unit.

[0046] Step 8: Carry out construction layer by layer according to the above steps. When the designed number of layers is reached, the geogrid 1 in the reinforced steep slope is automatically tensioned due to the dual effects of trench excavation and deadweight. No roller is needed to roll the uncompactable part 6 at the edge of the roadbed, which reduces the construction cost, shortens the construction period, achieves the desired effect, and facilitates the construction.

[0047] Step 9: After filling to the specified height, manually install the grid prefabricated blocks 16, fix the grid slope protection with 1m long anchor rods 21, lay 15cm thick pebbles 17 inside the grid prefabricated blocks 16 to fill the grid mesh holes, and fill the gaps on the slope with gravel soil. After reaching the top, cast-in-place concrete capping 18 and pavement structure layer 19 are implemented.

[0048] The main technical problem solved by the present invention is the problem of integrated construction of the free surface of a geogrid-gravel soil reinforced steep slope embankment and grid tensioning. A geogrid-reinforced soil structure that is more conducive to giving full play to the reinforcement performance of the geogrid, thereby improving the stability of the reinforced steep slope embankment, and a matching construction process are used to solve the problems of difficulty in compacting the soil near the free surface and time-consuming and labor-intensive grid tensioning during geogrid laying.

[0049] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A geogrid steep slope embankment structure with a return bag, characterized in that: A plurality of geogrid layers are stacked from bottom to top on the free surface of the slope, a gravel cushion adjustment layer (15) and a grid prefabricated block (16) are sequentially laid on the outer side of the geogrid layer, and pebbles (17) are filled in the grid prefabricated block (16); Each backpack geogrid layer comprises a geogrid (1) for wrapping gravel soil roadbed filler, the cross section of the geogrid (1) is a trapezoidal groove structure with one side open, the closed end of the geogrid (1) is located on the free surface of the slope, the end of the geogrid (1) is fixed to the roadbed, the inner wall of the geogrid (1) is paved with a geotextile, and the geotextile is filled with gravel soil roadbed filler; the backpack geogrid of the lower layer is connected to the geogrid of the upper layer by a connecting rod, so that the upper and lower geogrids form a semi-closed annular backpack geogrid layer at the free surface of the slope, which has a lateral restraining effect on the soil; A shallow arc groove (11) is provided on the top surface of each layer of the back-wrapped geogrid layer, and the adjacent geogrid (1) is in contact with the shallow arc groove (11) and is in a tensioned state. The width of the shallow arc groove (11) is 1 m and the depth is less than 20 cm. The construction method of the return-type geogrid steep slope embankment structure comprises the following steps: Step 1: Draw a slope edge line (13) and a geogrid laying edge line (12) inside the slope on the steps of the embankment, and excavate a shallow arc groove (11) at the anchoring section of the geogrid (1); Step 2: laying the geogrid (1) along the laying edge line (12) of the geogrid inside the slope, placing the geogrid (2) of the return section of the geogrid (1) outside the slope edge line (13), and tightening the geogrid (1) and fixing it to the roadbed; Step 3, laying a geotextile on the geogrid (1) of step 2, the geotextile being fixedly connected to the geogrid (1), and the return section of the geotextile (3) being placed outside the edge line (13) of the slope; Step 4, filling gravel roadbed filler (20) on the geogrid (1) until the roadbed filler reaches the top surface (7) and then rolling. After rolling, the geogrid (1) is in close contact with the shallow arc groove (11), and then the slope is processed according to the slope design slope rate; Step 5, the geotextile (3) and the geogrid (2) of the backpacking section are backpacked upward along the slope to the top surface of the compacted roadbed fill (8), thereby forming a backpacking geogrid layer; Step 6, repeating steps 1-5 on the backpack geogrid layer, constructing layer by layer until the designed number of layers is reached, and the backpack geogrid (2) of the lower layer is fixedly connected to the geogrid (1) of the upper layer; Step 7: After the designed number of layers is constructed, a concrete capping layer (18) and a pavement structure layer (19) are cast on the top of the top geogrid layer, and a gravel cushion adjustment layer (15) and a grid prefabricated block (16) are laid in sequence on the outside of the geogrid layer, and pebbles (17) are filled in the grid prefabricated blocks (16).

2. The geogrid steep slope embankment structure according to claim 1, characterized in that: The height of the geogrid layer is 50 cm.

3. The geogrid steep slope embankment structure according to claim 1, characterized in that: The slope of the embankment is gentler than any slope of 1:0.5.

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