A protection structure for soft foundation slope and a construction method thereof

Abstract

This invention relates to the field of slope protection technology, and discloses a protective structure for soft soil slopes and its construction method. The protective structure includes longitudinal members, transverse members, helical blade anchor rods, flow-guiding retaining strips, and composite geocell sheets. The longitudinal and transverse members are orthogonally interlocked to form a planar grid, and the sealed cavities below the normal water level are filled with closed-cell polyurethane foam. The helical blade anchor rods have annular anchor plates embedded in the soil below the grid nodes. The flow-guiding retaining strips are arranged on the downslope side of the transverse members. A filter layer is attached to the bottom surface of the composite geocell sheets.

Description

Technical Field

[0001] This invention relates to the field of slope protection technology, and more specifically, to a protective structure for soft soil slopes and its construction method. Background Technology

[0002] The soft soil slopes in the reservoir drawdown zone and riverbank tidal zone have been subjected to repeated rises and falls in water level over a long period of time, resulting in poor slope stability. Therefore, it is necessary to use a grid slope protection frame combined with anchoring components to protect the slope.

[0003] In existing technologies, fiber-reinforced composite hollow rectangular section members are usually assembled into a grid slope protection frame by orthogonal insertion of slots. The frame is fixed by screwing helical blade anchor rods into the soft soil of the slope. Geocell sheets are laid in the cells enclosed by the grid to form zonal constraints on the slope soil.

[0004] However, the aforementioned existing technology has the following drawbacks: after the hollow rod is immersed in water, the sealed cavity generates buoyancy, which forms a pull-out component along the slope normal. This pull-out component acts cyclically on the contact interface between the helical blade anchor rod and the soft soil, causing the surrounding soil to gradually loosen and lose its gripping force. The helical blade anchor rod is at risk of being pulled out. At the same time, after the water level drops, the backflow of water forms local erosion cavities at the bottom of the geogrid cell. The loss of soil under the geocell sheet causes it to collapse, and the geogrid loses its effective constraint on the slope soil. Summary of the Invention

[0005] This invention provides a protective structure for soft soil slopes and its construction method, solving the technical problems of anchorage failure and slope erosion caused by repeated rises and falls in water level in drawdown zone slopes in related technologies.

[0006] This invention discloses a protective structure for soft soil slopes, comprising multiple longitudinal members and multiple transverse members. Both longitudinal and transverse members are hollow rectangular cross-section profiles made of fiber-reinforced composite materials. The longitudinal and transverse members are orthogonally connected by through slots to form a planar grid attached to the slope surface. Each member has an inner partition fixed at intervals along its length within its cavity, which divides the cavity into multiple independent sealed sections. The sealed sections located below the normal water level are filled with closed-cell polyurethane foam. Spiral blade-type anchor rods are installed at the grid nodes, passing through vertical through holes and screwed into the soft soil of the slope. The rod body has an annular anchor plate embedded in the soil below the grid node. Guide retaining strips are arranged along the contour lines of the slope on the downslope side of each row of transverse members. Composite geocell sheets are laid in each grid cell, with a filter layer for trapping fine soil particles attached to the bottom surface.

[0007] Furthermore, the width of the through slot is smaller than the corresponding dimension of the cross-section of the member to be inserted, while the width of the slot bottom is the same as the dimension of the cross-section of the member to be inserted. The cross-section of the through slot is narrow at the opening and wide at the bottom. The two side walls of the through slot opening are provided with inwardly contracting elastic lips. When the cross-section of the member to be inserted is squeezed by the elastic lips, it deforms outward elastically and falls through the slot opening into the bottom of the slot. After the elastic lips rebound to the initial position, they clamp the inserted member cross-section from both sides, preventing the member from coming out along the normal direction of the through slot.

[0008] Furthermore, the outer periphery of the inner partition matches the rectangular cross-section of the inner wall of the rod, and the outer periphery of the inner partition is sealed to the inner wall of the rod by adhesive bonding. Closed-cell polyurethane foam filler fills the internal space of the sealed cavity, replacing the original air in the sealed cavity. The sealed cavity located above the normal water level remains empty.

[0009] Furthermore, the tip of the helical blade anchor rod is integrally formed with helical blades. During the twisting process, the helical blades cut into the soft soil of the slope and provide lateral friction resistance and end bearing capacity. An annular anchor plate is welded to the middle of the rod body of the helical blade anchor rod, and the outer diameter of the annular anchor plate is larger than the diameter of the vertical through hole. The annular anchor plate is embedded in the soil at a predetermined depth below the grid node. When the grid is subjected to a pull-out force along the slope normal, the pull-out force is transmitted to the annular anchor plate through the rod body, and the soil above the annular anchor plate generates passive earth pressure to resist the pull-out force.

[0010] Furthermore, an expanding head is fixedly connected to the upper end of the spiral blade anchor rod. The outer diameter of the expanding head is larger than the diameter of the vertical through hole, and the expanding head abuts against the upper surface of the grid node. The expanding head and the annular anchor plate are located on both sides of the grid node, respectively, together constraining the grid node to the spiral blade anchor rod. The expanding head is fixed to the upper end of the rod through a threaded connection.

[0011] Furthermore, the guide strip is an L-shaped cross-section strip member made of fiber-reinforced composite material, including a vertical plate and a horizontal wing plate integrally extending from the lower end of the vertical plate in the downhill direction. The vertical plate is arranged along the contour line of the slope on the downhill side of the transverse member, with the lower edge of the vertical plate abutting the slope surface. The horizontal wing plate covers the contact area between the lower end of the vertical plate and the slope surface.

[0012] Furthermore, the upper edge of the vertical plate is fastened to the horizontal member by multiple U-shaped clips spaced apart along the length. The open end of the U-shaped clips clamps the outer wall of the horizontal member, and the closed end of the U-shaped clips presses against the upper edge of the vertical plate, thus suspending and fixing the vertical plate to the lower slope side of the horizontal member.

[0013] Furthermore, the filter layer is a needle-punched nonwoven geotextile, which is attached to the bottom surface of the composite geocell sheet. The porous structure of the needle-punched nonwoven geotextile allows water to pass through while trapping fine soil particles.

[0014] Furthermore, the edges of the needle-punched nonwoven geotextile extend beyond the edges of the composite geocell sheet. These extended edges are folded over and overlapped onto the upper surface of adjacent members. The folded edges are then secured to the upper surface of the members using binding straps. These straps are spaced apart along the length of the members, pressing the edges of the needle-punched nonwoven geotextile tightly against the upper surface of the members, thus covering the gap between the composite geocell sheet and adjacent members.

[0015] Furthermore, the longitudinal members extend along the slope from the foot to the top, while the transverse members extend along the contour lines of the slope. The longitudinal members have transverse through-groove slots at equal intervals along their length on both sides, and the transverse members have longitudinal through-groove slots at equal intervals along their length on both sides, with the through-groove slots penetrating the sidewalls of the members.

[0016] This invention discloses a construction method for a soft soil slope grid protection structure, including: determining the water level range of each sealed cavity section on each member according to the normal water level elevation on the slope; installing inner partitions at intervals along the length direction in the cavity of each member; bonding and sealing the outer periphery of the inner partitions to the inner wall of the member to form multiple independent sealed cavities; injecting closed-cell polyurethane foam filler into the corresponding sealed cavities below the normal water level; completing the slot processing and cutting of each member; laying multiple longitudinal members along the slope surface; and interlocking transverse members with longitudinal members in a row from the slope foot to the slope top to form a planar grid covering the slope surface; and inserting helical blade anchor rods from each grid node. Insert the vertical through hole from bottom to top, and screw the spiral blade anchor rod so that the tip of the spiral blade cuts into the soft soil of the slope until the annular anchor plate sinks to a predetermined depth below the grid node. Screw the enlarged head onto the upper end of the spiral blade anchor rod through a threaded connection. Arrange the flow guide strip along the contour line of the slope on the downslope side of each row of transverse members, and use U-shaped clips to fasten the upper edge of the vertical plate of the flow guide strip to the transverse members. Unfold the composite geocell sheet in each grid cell, and fold the part of the needle-punched nonwoven geotextile that extends beyond the edge of the composite geocell sheet to the upper surface of the adjacent member. Use binding tape to fix the edge of the needle-punched nonwoven geotextile to the member at intervals along the length of the member.

[0017] The beneficial effects of this invention are as follows: This invention injects closed-cell polyurethane foam filler into the sealed cavity of the rod in the section below the normal water level, reducing the cyclic pull-out force applied to the helical blade anchor rod along the slope normal when the rod is submerged in water, and reducing the risk of gradual loosening of the surrounding soil due to cyclic load. The helical blade anchor rod has an annular anchor plate embedded in the soil below the grid node, forming an independent pull-out bearing path, so that the anchoring system can still maintain effective pull-out bearing capacity when the soil around the helical blade is loosened to a certain extent. The flow guide strip intercepts and disperses the water flow down the slope when the water level drops, inhibiting the local erosion of the slope soil in the grid cell. The filter layer attached to the bottom surface of the composite geocell sheet intercepts fine soil particles, and the gap between the edge of the sheet and the rod is covered by folding and overlapping, so that the surface soil of the slope can be retained. The zonal constraint function of the grid on the slope soil can be continuously maintained, solving the technical problems of anchoring failure and slope soil loss of the protection structure of soft foundation slope under repeated water level fluctuations. Attached Figure Description

[0018] Figure 1 This is a front view of the protective structure for soft soil slopes according to the present invention; Figure 2 This is a longitudinal sectional view of the protective structure for soft soil slopes of the present invention along the longitudinal members; Figure 3 This is a cross-sectional view of the orthogonal insertion point of the longitudinal and transverse rod slots of the present invention; Figure 4 This is a cross-sectional view of the installation of the flow guide retaining strip and the laying of the composite geocell sheet of the present invention; Figure 5 This is a schematic diagram of the spiral blade type anchor rod of the present invention; Figure 6 This is an isometric view of the protective structure for soft soil slopes according to the present invention.

[0019] In the diagram: Longitudinal member-1, Transverse member-2, Through slot-3, Elastic lip-4, Inner partition-5, Closed-cell polyurethane foam filler-6, Spiral blade anchor rod-7, Spiral blade-8, Annular anchor plate-9, Expanded diameter head-10, Vertical through hole-11, Guide barrier strip-12, Vertical plate-13, Horizontal wing plate-14, U-shaped clamp-15, Composite geocell sheet-16, Needle-punched nonwoven geotextile-17, Binding strap-18. Detailed Implementation

[0020] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0021] In soft soil slope protection projects in reservoir drawdown zones or riverbank tidal areas, fiber-reinforced composite hollow rectangular section members are assembled into a grid slope protection frame through orthogonal insertion of slots. This frame is then fixed by helical blade-type anchor rods 7 screwed into the soft soil of the slope. Geocell sheets are laid within the grid cells to provide zoned constraint on the slope soil. However, drawdown zone slopes experience repeated rises and falls in water level over a long period. When the grid frame is submerged in water during a rise, the sealed cavities of the hollow members generate buoyancy. This buoyancy forms a pull-out component along the slope normal, repeatedly acting on the contact interface between the helical blade-type anchor rods 7 and the soft soil. This causes the soil around the helical blade-type anchor rods 7 to gradually loosen and lose its grip due to cyclic loading, eventually leading to the helical blade-type anchor rods 7 being pulled out. Meanwhile, as the water level drops, the receding water flow creates localized erosion cavities at the bottom of the geogrid cells. The loss of soil beneath the geocell sheets causes the geocell sheets to collapse, and the geogrid loses its effective constraint on the slope soil.

[0022] like Figure 1-6 As shown, according to an embodiment of this invention, a protective structure for soft soil slopes is provided to form zoned constraints on the soft soil surface under conditions of repeated rises and falls in water level. The protective structure for soft soil slopes includes at least multiple longitudinal members 1, multiple transverse members 2, several helical blade anchor rods 7, several flow-guiding retaining strips 12, and multiple composite geocell sheets 16. The longitudinal members 1 and transverse members 2 are orthogonally interlocked to form a planar grid that is attached to the slope surface. The cavity of each member is divided into multiple independent sealed cavities by an inner partition 5. The sealed cavities located below the normal water level are filled with closed-cell polyurethane foam filler 6 to reduce the buoyancy generated when the members are immersed in water. A helical blade anchor rod 7 is provided at each grid node. The helical blade anchor rod 7 passes through the vertical through hole 11 at the node and is screwed into the soft soil surface of the slope. The rod body is provided with an annular anchor plate 9 to provide an independent pull-out bearing path. The flow-guiding retaining strips 12 are installed on the downslope side of each row of transverse members 2 to intercept the water flow flowing down the slope when the water level drops. The composite geocell sheet 16 is laid in each geocell cell, and the bottom surface of the composite geocell sheet 16 is attached with a filter layer to trap fine soil particles.

[0023] The following is a detailed explanation of the structure of each part.

[0024] Both longitudinal member 1 and transverse member 2 are hollow rectangular cross-section profiles made of fiber-reinforced composite material. Longitudinal member 1 extends along the slope from the foot to the top, while transverse member 2 extends along the contour lines of the slope. Transverse through-slots 3 are equally spaced along the length of both sides of longitudinal member 1, penetrating the sidewalls along the width of the member. Similarly, longitudinal through-slots 3 with identical structures are equally spaced along the length of both sides of transverse member 2. Longitudinal member 1 and transverse member 2 are orthogonally inserted at corresponding positions in their respective slots. The slots constrain the inserted member cross-section to prevent it from dislodging, thus forming a planar grid covering the slope.

[0025] In some embodiments, the groove opening width is slightly smaller than the corresponding dimension of the cross-section of the rod to be inserted, and the groove bottom width is the same as the dimension of the cross-section of the rod to be inserted. The groove cross-section is narrow at the opening and wide at the bottom. The two side walls of the groove opening are provided with inwardly contracting elastic lips 4. During assembly, the cross-section of the rod to be inserted compresses the elastic lips 4, causing it to elastically deform outward. After passing through the groove opening, the rod cross-section falls into the groove bottom, and the elastic lips 4 spring back to their initial position. The springback elastic lips 4 clamp the inserted rod cross-section from both sides. The groove opening width of the elastic lips 4 is smaller than the dimension of the rod cross-section, thereby preventing the rod from coming out along the groove normal, completing the orthogonal insertion.

[0026] Each rod has multiple inner partitions 5 fixed at intervals along its length within its cavity. The outer periphery of the inner partition 5 matches the rectangular cross-section of the inner wall of the rod. The outer edge of the inner partition 5 is sealed to the inner wall of the rod by adhesive bonding, dividing the continuous cavity of the rod into multiple independent sealed cavity segments arranged sequentially along its length. The water level range of each sealed cavity segment on each rod is determined based on the normal water level elevation on the slope: the sealed cavity segments located below the normal water level are filled with closed-cell polyurethane foam filler 6, which fills the entire internal space of the sealed cavity segment, replacing the original air in the sealed cavity segment; the sealed cavity segments located above the normal water level remain empty. The density of the closed-cell polyurethane foam filler 6 is close to that of water. When the rod is immersed in water, the sealed cavity section filled with the closed-cell polyurethane foam filler 6 no longer generates cavity buoyancy. The buoyancy of this section is close to the equivalent component of the self-weight of the rod wall in water, thereby reducing the cyclic pull-out force applied to the helical blade anchor rod 7 along the slope normal direction when the rod is immersed in water.

[0027] At each grid node, a coaxial vertical through hole 11 is provided at the intersection of the longitudinal member 1 and the transverse member 2, penetrating the member wall at the intersection. The helical blade anchor rod 7 is a metal rod, with a helical blade 8 integrally formed at its tip. During the screwing process of the helical blade anchor rod 7, the helical blade 8 cuts into the soft soil of the slope and provides lateral friction resistance and end bearing force. A ring-shaped anchor plate 9 is welded to the middle of the rod body of the helical blade anchor rod 7. The outer diameter of the ring-shaped anchor plate 9 is larger than the diameter of the vertical through hole 11 of the grid node. After the helical blade anchor rod 7 passes through the vertical through hole 11 from above the grid node, it is screwed into the soft soil of the slope. As the screwing depth increases, the ring-shaped anchor plate 9 sinks with the rod body to a predetermined depth below the grid node and is buried in the soil. After the annular anchor plate 9 is embedded, when the grid is subjected to a pull-out force along the slope normal, the pull-out force is transmitted to the annular anchor plate 9 through the body of the spiral blade anchor rod 7. The soil above the annular anchor plate 9 generates passive earth pressure to resist the pull-out force, thus forming a pull-out bearing path independent of the end bearing force and side friction of the spiral blade 8.

[0028] It should be noted that the outer diameter of the annular anchor plate 9 is larger than the diameter of the vertical through hole 11. Therefore, before the helical blade anchor rod 7 is inserted into the vertical through hole 11, it must first be inserted from below the vertical through hole 11 upwards, so that the annular anchor plate 9 is located below the grid node. Then, the helical blade anchor rod 7 is screwed into the soft soil of the slope. After the helical blade anchor rod 7 is screwed in place, the upper end of the rod extends from the vertical through hole 11 to above the grid node. An expansion head 10 is fixedly connected to the upper end of the rod. The outer diameter of the expansion head 10 is larger than the diameter of the vertical through hole 11. The expansion head 10 abuts against the upper surface of the grid node, forming a limiting constraint on the grid node along the slope normal. The expansion head 10 and the annular anchor plate 9 are located on both sides of the grid node, and together they constrain the grid node to the helical blade anchor rod 7, preventing the grid from detaching from the slope under buoyancy. The enlarged head 10 is fixed to the upper end of the spiral blade anchor rod 7 by a threaded connection, and after being screwed in place, it fits and locks against the end face of the rod.

[0029] The flow guide strip 12 is arranged along the contour line of the slope on the downslope side of each row of transverse members 2 and connected to the transverse members 2. The vertical extension of the flow guide strip 12 intercepts the water flow flowing down the slope when the water level drops, forcing the water flow to disperse and discharge along the contour line.

[0030] In some embodiments, the guide strip 12 is an L-shaped cross-section strip member made of fiber-reinforced composite material, including a vertical plate 13 and a horizontal wing plate 14 integrally extending from the lower end of the vertical plate 13 in the downslope direction. The vertical plate 13 is arranged along the contour line of the slope on the downslope side of each row of transverse members 2, and the upper edge of the vertical plate 13 is fastened to the transverse members 2 by a plurality of U-shaped clips 15 spaced apart along the length direction. The open end of the U-shaped clip 15 clamps the outer wall of the transverse member 2, and the closed end of the U-shaped clip 15 presses against the upper edge of the vertical plate 13, thereby suspending and fixing the vertical plate 13 to the downslope side of the transverse member 2. The lower edge of the vertical plate 13 abuts against the slope surface. When the water level drops, the water flowing down the slope is intercepted by the vertical plate 13 and forced to disperse and discharge along the extension direction of the vertical plate 13, i.e., the contour line of the slope, reducing the erosion effect of concentrated scouring on the slope soil within the grid cell. The horizontal wing plate 14 is attached to the contact area between the lower end of the vertical plate 13 and the slope surface, forming a cover over the area and reducing the possibility of water flow seeping into the grid cell from the lower end of the vertical plate 13 and eroding the slope soil.

[0031] Composite geocell sheet 16 is laid inside each geocell cell, and the planar dimensions of composite geocell sheet 16 match the internal space of the geocell cell. A filter layer is attached to the bottom surface of composite geocell sheet 16. The pore structure of the filter layer allows water to flow through but traps fine soil particles, preventing the surface soil of the slope inside the geocell cell from being lost due to water infiltration.

[0032] In some embodiments, the filter layer is a needle-punched nonwoven geotextile 17, which is attached to the bottom surface of the composite geocell sheet 16. The edges of the needle-punched nonwoven geotextile 17 extend beyond the edges of the composite geocell sheet 16. These extended edges are folded over and overlapped onto the upper surface of adjacent members, and are secured to the upper surface of the members using binding straps 18. The binding straps 18 are spaced apart along the length of the members, pressing the edges of the needle-punched nonwoven geotextile 17 tightly against the upper surface of the members. This covers the gap between the composite geocell sheet 16 and adjacent members, preventing fine soil particles from escaping through the gap between the edges of the composite geocell sheet 16 and the members.

[0033] The construction of the protective structure for soft soil slopes shall be carried out in accordance with the following steps.

[0034] Step 1: Determine the water level range of each sealing cavity section on each rod based on the normal water level elevation on the slope. Install inner partitions 5 at intervals along the length of the cavity in each rod, and glue and seal the outer periphery of the inner partitions 5 to the inner wall of the rod, forming multiple independent sealing cavities. Inject closed-cell polyurethane foam filler 6 into the sealing cavities below the normal water level, ensuring the closed-cell polyurethane foam filler 6 fills the internal space of the sealing cavity. Complete the processing of the through grooves 3 in each rod and cut the rods accordingly.

[0035] Step two: Lay multiple longitudinal members 1 along the slope surface. From the foot of the slope to the top, align the transverse members 2 orthogonally with the longitudinal members 1 row by row. Align the cross-section of the transverse members 2 with the transverse through-groove 3 on the side of the longitudinal members 1. The cross-section of the transverse members 2 compresses the elastic lip 4 at the opening of the transverse through-groove 3, causing it to elastically deform. After the cross-section of the member passes through the groove, it falls into the bottom of the groove. The elastic lip 4 rebounds and clamps the transverse member 2, completing the orthogonal insertion. At the same time, the cross-section of the longitudinal members 1 also inserts into the longitudinal through-groove 3 on the side of the transverse members 2. After row by row insertion is completed, a planar grid covering the slope surface is formed.

[0036] Step 3: At each grid node, insert the helical blade anchor rod 7 from below the grid node into the vertical through hole 11, so that the annular anchor plate 9 is located below the grid node, and the upper end of the rod extends from the vertical through hole 11 to above the grid node. Tighten the helical blade anchor rod 7 so that the tip of the helical blade 8 cuts into the soft soil of the slope, and continue to tighten until the annular anchor plate 9 is sunk to a predetermined depth below the grid node and buried in the soil. Secure the expansion head 10 to the upper end of the helical blade anchor rod 7 through a threaded connection, so that the expansion head 10 abuts against the upper surface of the grid node, and the grid node is constrained between the expansion head 10 and the annular anchor plate 9.

[0037] Step four: Arrange the guide strips 12 along the contour lines of the slope on the downslope side of each row of transverse members 2. Use U-shaped clips 15 to fasten the upper edge of the vertical plate 13 of the guide strip 12 to the transverse member 2, so that the lower edge of the vertical plate 13 abuts against the slope surface, and the horizontal wing plate 14 covers the slope surface.

[0038] Step 5: Unfold the composite geocell sheet 16 within each geocell cell, so that the needle-punched nonwoven geotextile 17 on the bottom surface of the composite geocell sheet 16 adheres to the slope. Fold over the portion of the needle-punched nonwoven geotextile 17 extending beyond the edge of the composite geocell sheet 16 and overlap it onto the upper surface of the adjacent rod. Secure the edges of the needle-punched nonwoven geotextile 17 to the rod at intervals along the length of the rod using binding straps 18.

[0039] In the protective structure for soft soil slopes, closed-cell polyurethane foam 6 is injected into the sealed cavity of the members in the section below the normal water level. The closed-cell polyurethane foam 6 replaces the original air in the sealed cavity. Therefore, when the members are submerged in water, no cavity buoyancy is generated in this section. The density of the closed-cell polyurethane foam 6 is close to that of water, so the buoyancy in this section is close to the equivalent component of the member wall's self-weight in water. The cyclic pull-out force applied to the helical blade anchor rod 7 along the slope normal direction when the members are submerged in water is reduced, thus reducing the risk of gradual loosening of the soil around the helical blade anchor rod 7 due to cyclic load.

[0040] Furthermore, the annular anchor plate 9, welded to the middle of the spiral blade anchor rod 7, is embedded in the soil at a predetermined depth below the grid node. When the grid is subjected to residual pull-out force, the soil above the annular anchor plate 9 generates passive earth pressure to bear the pull-out force, forming a pull-out bearing path independent of the end bearing force and side friction of the spiral blade 8. Therefore, even if the soil around the spiral blade 8 relaxes to a certain extent under cyclic loading, the annular anchor plate 9 can still provide effective pull-out bearing capacity, avoiding anchoring failure. The enlarged head 10 is fixed to the upper end of the spiral blade anchor rod 7 via a threaded connection, abutting against the upper surface of the grid node, and together with the annular anchor plate 9, constrains the grid node to the spiral blade anchor rod 7, preventing the grid from detaching from the slope under the action of buoyancy and pull-out force.

[0041] The vertical plates 13 of the guide retaining strip 12 are arranged along the contour lines of the slope on the downslope side of each row of transverse members 2. During the water level drop, they intercept the water flowing down the slope and force the water to disperse and discharge along the contour lines. Therefore, the scouring force that was originally concentrated on the slope soil within the grid cell is dispersed, and the formation of local erosion cavities is suppressed. The horizontal flange 14 covers the contact area between the lower end of the vertical plate 13 and the slope surface, further reducing the possibility of water seeping into the grid cell from the lower end of the vertical plate 13.

[0042] The needle-punched nonwoven geotextile 17 attached to the bottom surface of the composite geocell sheet 16 allows water to pass through while trapping fine soil particles, preventing the loss of surface soil within the geocell cells due to seepage. The edges of the needle-punched nonwoven geotextile 17 are folded over and secured to the upper surface of adjacent members, covering the gaps between the edges of the composite geocell sheet 16 and the members, preventing fine soil particles from flowing out through these gaps. Therefore, the slope soil beneath the composite geocell sheet 16 is retained, allowing the composite geocell sheet 16 to continuously adhere to the slope, and maintaining the geocell's zonal constraint function on the slope soil.

[0043] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A protective structure for soft soil slopes, characterized in that, include: Multiple longitudinal members (1) and multiple transverse members (2) are hollow members. The longitudinal members (1) and transverse members (2) are orthogonally connected through through slots (3) to form a planar grid that is attached to the slope. Each member has an inner partition (5) fixed at intervals along the length direction in the cavity. The inner partition (5) divides the cavity into multiple independent sealed cavities. The sealed cavities located below the normal water level are filled with closed-cell polyurethane foam filler (6). The spiral blade type anchor rod (7) is set at the grid node, passes through the vertical through hole (11) and is screwed into the soft soil of the slope. The rod body is provided with an annular anchor plate (9) embedded in the soil below the grid node. The guide bar (12) is arranged along the contour line of the slope on the downslope side of each row of transverse members (2); Composite geocell sheet (16) is laid in each geocell cell, with a filter layer attached to the bottom to trap fine soil particles.

2. The protective structure for soft soil slopes according to claim 1, characterized in that, The width of the slot of the through slot (3) is smaller than the corresponding size of the cross section of the rod to be inserted, and the width of the bottom of the slot is the same as the size of the cross section of the rod to be inserted. The cross section of the through slot (3) is narrow at the opening and wide at the bottom. The two side walls of the slot of the through slot (3) are provided with inwardly contracting elastic lips (4). The cross section of the rod to be inserted squeezes the elastic lips (4) to make it elastically deform outward and then falls into the bottom of the slot through the slot. After the elastic lips (4) rebound to the initial position, they clamp the cross section of the inserted rod from both sides to prevent the rod from coming out along the normal direction of the through slot (3).

3. The protective structure for soft soil slopes according to claim 1, characterized in that, The outer periphery of the inner partition (5) matches the rectangular cross section of the inner wall of the rod. The outer periphery of the inner partition (5) and the inner wall of the rod are sealed by adhesive bonding. The closed-cell polyurethane foam filler (6) fills the internal space of the sealed cavity, replacing the original air in the sealed cavity. The sealed cavity located above the normal water level remains in an empty state.

4. The protective structure for soft soil slopes according to claim 1, characterized in that, The tip of the spiral blade anchor rod (7) is integrally formed with a spiral blade (8). During the twisting process, the spiral blade (8) cuts into the soft soil of the slope and provides side friction resistance and end bearing force. The annular anchor plate (9) is welded to the middle of the rod body of the spiral blade anchor rod (7). The outer diameter of the annular anchor plate (9) is larger than the diameter of the vertical through hole (11). The annular anchor plate (9) is buried in the soil at a predetermined depth below the grid node. When the grid is subjected to a pull-out force along the slope normal, the pull-out force is transmitted to the annular anchor plate (9) through the rod body. The soil above the annular anchor plate (9) generates passive earth pressure to resist the pull-out force.

5. The protective structure for soft soil slopes according to claim 4, characterized in that, An expanding head (10) is fixedly connected to the upper end of the rod body of the spiral blade anchor rod (7). The outer diameter of the expanding head (10) is larger than the diameter of the vertical through hole (11). The expanding head (10) abuts against the upper surface of the grid node. The expanding head (10) and the annular anchor plate (9) are located on both sides of the grid node, and together they constrain the grid node to the rod body of the spiral blade anchor rod (7). The expanding head (10) is fixed to the upper end of the rod body by a threaded connection.

6. The protective structure for soft soil slopes according to claim 1, characterized in that, The guide bar (12) is an L-shaped cross-section strip member, including a vertical plate (13) and a horizontal wing plate (14) extending integrally from the lower end of the vertical plate (13) in the downhill direction; the vertical plate (13) is arranged along the contour line of the slope on the downhill side of the transverse member (2), and the lower edge of the vertical plate (13) abuts against the slope surface; the horizontal wing plate (14) is attached to the contact area between the lower end of the vertical plate (13) and the slope surface.

7. The protective structure for soft soil slopes according to claim 6, characterized in that, The upper edge of the vertical plate (13) is fastened to the horizontal member (2) by a plurality of U-shaped clips (15) spaced apart along the length direction; the open end of the U-shaped clip (15) clamps the outer wall of the horizontal member (2), and the closed end of the U-shaped clip (15) presses the upper edge of the vertical plate (13), thus suspending and fixing the vertical plate (13) to the lower slope side of the horizontal member (2).

8. The protective structure for soft soil slopes according to claim 1, characterized in that, The filter layer is a needle-punched nonwoven geotextile (17), which is attached to the bottom surface of the composite geocell sheet (16). The porous structure of the needle-punched nonwoven geotextile (17) allows water to pass through but traps fine soil particles.

9. The protective structure for soft soil slopes according to claim 8, characterized in that, The edges of the needle-punched nonwoven geotextile (17) extend beyond the edges of the composite geocell sheet (16). The extended edges of the needle-punched nonwoven geotextile (17) are folded over and overlapped on the upper surface of the adjacent rod. The folded edges of the needle-punched nonwoven geotextile (17) are fixed to the upper surface of the rod by binding straps (18). The binding straps (18) are distributed at intervals along the length of the rod, pressing the edges of the needle-punched nonwoven geotextile (17) tightly against the upper surface of the rod, so that the gap between the composite geocell sheet (16) and the adjacent rod is covered by the needle-punched nonwoven geotextile (17).

10. The protective structure for soft soil slopes according to claim 1, characterized in that, Both the longitudinal member (1) and the transverse member (2) are hollow rectangular cross-section profiles made of fiber reinforced composite material; the longitudinal member (1) extends along the slope from the foot of the slope to the top of the slope, and the transverse member (2) extends along the contour line of the slope; the two sides of the longitudinal member (1) are provided with transverse through slots (3) at equal intervals along the length direction, and the two sides of the transverse member (2) are provided with longitudinal through slots (3) at equal intervals along the length direction, and the through slots (3) penetrate through the side wall of the member.

Images