Supporting structure of high slope and foundation pit

Abstract

The utility model discloses a supporting structure for a high slope and a foundation pit, relates to the field of foundation engineering, and aims to improve the integrity and the stability of supporting the high slope by adopting a lattice beam and ensure the safety of the supporting structure. According to the technical scheme, the supporting structure of the high slope and the foundation pit comprises an intercepting ditch and a coping beam at the top of the slope, a lattice beam on the slope surface, a ground beam and a drainage ditch at the bottom of the slope and a stiffening pile arranged in the slope body in a downward inclined mode, and the stiffening pile comprises an anchoring body obtained through high-pressure jet grouting in a hole and a stress rib embedded in the anchoring body; the lattice beam comprises cross beams and vertical beams, the upper ends of the vertical beams are connected with the coping beam, the lower ends of the vertical beams are connected with the ground beam, and the joints of the cross beams and the vertical beams are fixed to the stiffening piles in a tensioning mode; supporting piles are arranged at the slope bottom at intervals, a foundation pit excavation area is arranged on one side of each supporting pile, and the supporting piles are connected through top beams and anchored to a slope body through anchoring devices. The method is used for supporting design of the high slope and the foundation pit.

Description

Technical Field

[0001] This utility model relates to the field of basic engineering, specifically a support structure for high slopes and foundation pits, and a construction method for the support structure. Background Technology

[0002] Below the edge of a certain farmland is a slope, and at the bottom of the slope is construction land. The construction land requires the excavation of a 12-meter-deep foundation pit, meaning a large-volume underground structure needs to be constructed at the bottom of the slope. Due to the construction land boundary restrictions, farmland cannot be occupied, and there is insufficient slope clearance. The horizontal distance between the excavation area and the boundary line is only 10 meters, resulting in a nearly vertical high slope of 26 meters. The soil layers of the high slope are moderately weathered mudstone and argillaceous sandstone. If the high slope becomes unstable and collapses, it will pose a significant threat to the safety of surrounding residents and construction workers, and could even lead to severe losses.

[0003] Because the top of the slope is farmland, the excavation area cannot be expanded, making a tiered slope construction plan infeasible. The excavation pit at the bottom of the slope creates an open space without a stable foundation for support, rendering gravity retaining walls unsuitable for high slopes. While grid beams are used for support on high slopes, they need to be securely anchored to the slope. Currently, anchor bolts are commonly used, but their anchoring effect is insufficient, and the overall integrity between the bolts and the grid is inadequate. Therefore, the slope support still carries a significant risk of instability, especially for high slopes. Utility Model Content

[0004] This utility model first provides a support structure for high slopes and foundation pits, with the aim of improving the integrity and stability of high slopes supported by lattice beams and ensuring the safety of the support structure.

[0005] The technical solution adopted in this utility model is: a support structure for high slopes and foundation pits, including a water interception ditch and capping beam at the top of the slope, a grid beam at the bottom of the slope, a ground beam at the bottom of the slope, and stiffening piles inclined downwards in the slope body. The stiffening piles include an anchor body obtained by high-pressure jet grouting in the hole, and a reinforcing bar embedded in the anchor body.

[0006] The lattice beam includes horizontal beams arranged along the horizontal direction and vertical beams perpendicular to the horizontal beams. The upper end of each vertical beam is connected to the capping beam, and the lower end of each vertical beam is connected to the ground beam. The capping beam, lattice beam, and ground beam are all reinforced concrete structures. Fixing holes are provided at the connection points of the horizontal beams and vertical beams. Stiffening piles correspond one-to-one with the fixing holes. The upper end of the reinforcing bar of the stiffening pile passes through the fixing hole and is tensioned and fixed by anchorage.

[0007] Support piles are also installed at intervals at the bottom of the slope. The center line of the support piles is vertical and they are made of reinforced concrete. The side of the support piles facing away from the slope is the excavation area of ​​the foundation pit. The lower end of the support piles is lower than the bottom of the foundation pit. The upper ends of each support pile are connected by a capping beam. The upper end of the support piles or the capping beam is anchored to the slope by an anchoring device. There is a drainage ditch between the capping beam and the ground beam.

[0008] To prevent corrosion of the reinforcing bars and anchorages at the upper end of the stiffening piles, a further step is taken: the fixing holes of the lattice beam are equipped with sealing anchor bodies that enclose the upper ends of the reinforcing bars and anchorages. Specifically, the sealing anchor body is a reinforced concrete structure, and the reinforcing bars of the sealing anchor body are welded and fixed to the anchorages.

[0009] To prevent structural damage to the lattice beam, the lattice beam is further provided with at least one structural joint, the plane corresponding to the structural joint is a vertical plane, and the structural joint is filled with asphalt filler.

[0010] The stiffening piles serve to reinforce the slope and tension and fix the grid beams. Specifically, the stiffening piles are divided into a sedimentation section and an anchorage section from bottom to top. The reinforcing bars of the stiffening piles are steel strands, which are distributed throughout the anchorage section. At least one anchor plate is also set at intervals along the length of the stiffening pile, and the steel strands pass through the anchor plate and are fixedly connected to the anchor plate.

[0011] To ensure that the stiffening piles at different locations can effectively anchor the lattice beam, the following further applies: the length directions of each stiffening pile are parallel to each other, and the length of the stiffening pile with a higher exposed position is greater than the length of the stiffening pile with a lower exposed position.

[0012] To prevent rainwater from seeping into the slope through the grid of the lattice beam and to promote slope drainage, the lattice beam is further reinforced with a lattice panel. The lattice panel includes a steel mesh fixedly connected to the lattice beam and a concrete slab formed by spraying concrete onto the steel mesh. The lattice panel is also equipped with drainage holes.

[0013] The support piles are arranged at intervals. To ensure the safety of the foundation pit excavation, the length of the support piles below the bottom elevation of the foundation pit is not less than the depth of the foundation pit, and the space between two adjacent support piles is a retaining wall formed by wire mesh and shotcrete.

[0014] The anchoring device is used to fix the upper end of the cap beam and the support pile. Furthermore, the anchoring device includes grout injected into the anchor hole and anchor cables embedded in the grout. The anchor cables are steel strands and there are at least two of them. The anchoring device is divided into a free section and an anchoring section. The free section is provided with wire rings at intervals along the length direction. The anchoring section is provided with wire rings and clamping rings at intervals. The grouting pipe and the anchor cable pass through each wire ring and clamping ring.

[0015] To facilitate the placement of anchoring devices and ensure that they can provide sufficient pull-out resistance, the anchoring devices are further arranged at an angle downwards, with pre-drilled holes in the capping beam or support piles. The exposed ends of the anchor cables pass through the pre-drilled holes, pads, bracing blocks, cover plates, and bearing plates in sequence, and are tensioned and fixed to the support piles or capping beams through the anchor heads.

[0016] This utility model also provides a method for supporting high slopes and foundation pits, specifically a construction method for the aforementioned support structure for high slopes and foundation pits. The aim is to improve the overall integrity and stability of high slopes supported by lattice beams, ensuring the safety of the support structure and construction. The method for supporting high slopes and foundation pits includes the following steps.

[0017] S1. Construct a drainage ditch at the top of the slope.

[0018] S2. Excavate the earthwork at the top of the slope and construct the capping beam. The capping beam is reserved with dowel bars for connection with the vertical beam of the lattice beam.

[0019] S3. Excavate the slope layer by layer from top to bottom to the operating platform according to the designed slope ratio, and trim the slope surface.

[0020] S4. Construction of stiffening piles: First, determine the location of the stiffening pile holes on the slope, then drill and clean the holes. The drilling direction is inclined downwards. Then, use a jet grouting machine to bring the reinforcing bars into the hole, perform high-pressure jet grouting, and obtain the anchor body.

[0021] To ensure the quality of the hole, the following steps are taken: in step S4, a down-the-hole drill is used for drilling, and casing is used for follow-up wall protection drilling.

[0022] The reinforcing bars of a single stiffening pile are often not a single strand. To facilitate the simultaneous fixing of all reinforcing bars and to improve the pull-out resistance of the stiffening pile, in step S4, the reinforcing bars of the stiffening pile are made of steel strands. At least one anchor plate is installed at intervals along the length of the stiffening pile. The steel strands pass through the anchor plates and are fixedly connected to them. Then, a jet grouting drill is used to bring the reinforcing bars and anchor plates into the hole. For example, a single stiffening pile has 3 to 4 reinforcing bars, and the anchor plates have 3 to 4 evenly spaced openings. The reinforcing bars pass through the openings of the anchor plates and are fixed with nuts.

[0023] The pressure of high-pressure jet grouting depends on the geological properties. To ensure that the stiffening piles can provide sufficient pull-out resistance, furthermore, in step S4, the length directions of each stiffening pile are parallel to each other, the length of the stiffening pile with a higher exposure position is greater than the length of the stiffening pile with a lower exposure position, and the pressure of high-pressure jet grouting is not less than 20 MPa.

[0024] S5. Construction of lattice beams and installation of lattice panels with steel reinforcement mesh, including: erecting scaffolding → grooving slopes → fabricating and tying steel reinforcement → installing formwork → pouring concrete and curing → removing formwork → tensioning and locking stiffening piles → clearing loose soil and stones from the slope → hanging steel reinforcement mesh on the slope → dismantling scaffolding; wherein, fixing holes are reserved at the connection between the horizontal and vertical beams of the lattice beams, and the stiffening piles are tensioned and fixed one by one with the fixing holes.

[0025] To facilitate the construction of the lattice beam, the following steps are further implemented: In step S4, before the grout solidifies, connecting steel bars are inserted into the hole, with part of the connecting steel bars inside the hole and part outside the hole; In step S5, when making and binding the steel bars, the connecting steel bars are connected to the steel bars of the lattice beam.

[0026] To prevent corrosion of the reinforcing bars and anchorages at the upper end of the stiffening pile, a further step is taken: after the stiffening pile is tensioned and locked, a sealing anchor body is constructed in the fixing hole to enclose the upper end of the reinforcing bars and anchorages. The sealing anchor body is a reinforced concrete structure, and the reinforcing bars of the sealing anchor body are welded and fixed to the anchorages.

[0027] S6. Shotcrete is applied within the grid of the lattice beam to obtain the lattice panel. To ensure the quality of the lattice panel and promote slope drainage, furthermore, in step S6, the lattice panel is sprayed at least twice, and the lattice panel is also equipped with drainage holes.

[0028] S7. Repeat steps S3 to S6 above until construction reaches the bottom of the slope.

[0029] To prevent structural damage to the lattice beam, further steps S3 and S7 are taken: the lattice beam is provided with at least one structural joint, the plane corresponding to the structural joint is a vertical plane, and the structural joint is filled with asphalt filler.

[0030] S8. When constructing the ground beam at the bottom of the slope, the lower end of each vertical beam is connected to the ground beam.

[0031] S9. Construct drainage ditches at the bottom of the slope.

[0032] S10. Construct support piles at the bottom of the slope. The centerline of the support piles is vertical and they are made of reinforced concrete. The lower end of the support piles is lower than the bottom of the foundation pit.

[0033] S11. Construction cap beam: The upper ends of each support pile are connected by the cap beam.

[0034] S12. Construction anchoring device, which is tensioned and fixed to the upper end of the support pile or the capping beam.

[0035] The anchoring device is used to fix the upper end of the capping beam and the support pile. Further, in step S11, the upper end of the support pile or the capping beam is reserved with a reserved hole for construction and fixing of the anchoring device; in step S12, the hole is drilled through the reserved hole, the hole is cleaned after drilling, the anchor cable is assembled and inserted into the anchor hole, grout is injected into the anchor hole under high pressure, and finally the anchor cable is tensioned and fixed to the support pile or the capping beam.

[0036] To further improve the pull-out resistance of the anchoring device, in step S12, the grouting pipes of the construction anchoring device are two, and high-pressure grouting is carried out in the anchor hole in two stages. The anchor cable is a steel strand and there are at least two strands. The anchoring device is divided into a free section and an anchoring section. The free section is equipped with a wire-laying ring at intervals, and the anchoring section is equipped with a wire-laying ring and a clamping ring at intervals. The anchor cable passes through each wire-laying ring and clamping ring. The anchoring device is arranged at an angle downwards. The exposed end of the anchor cable passes through the reserved hole, pad, diagonal brace, cover plate and bearing plate from bottom to top, and is fixed to the support pile or crown beam by tensioning through the anchoring head.

[0037] S13. Excavate the foundation pit in layers and support the pit walls between the support piles.

[0038] To ensure the safety of the foundation pit excavation, the support piles are arranged at intervals. In step S10, the pile holes of the support piles are drilled by a rotary drilling rig, and the length of the support piles below the bottom elevation of the foundation pit is not less than the depth of the foundation pit. In step S13, after the foundation pit is excavated in layers, a mesh is hung between two adjacent support piles and shotcrete is applied to form a retaining wall between the piles.

[0039] The beneficial effects of this utility model are as follows: the capping beam, lattice beam, ground beam, and stiffening pile together act as a frame for the slope, effectively addressing the soil arching effect, improving the integrity and stability of the support structure, and ensuring the safety of the slope support. After drilling, the reinforcing bars are inserted into the hole using a jet grouting rig, and high-pressure jet grouting is performed. During the grouting process, the surrounding soil and rock are simultaneously cut, and the grout, under high pressure, enters the fissures to form an anchor body, reinforcing the slope soil and rock, connecting unstable rock blocks with stable rock mass, and forming an integral structure with the anchor body, reinforcing bars, the bottom of the hole, and the surrounding soil and rock. This allows the stiffening pile to share the load through the reinforcing bars, the anchor body, and the surrounding soil and rock. During the high-pressure jet grouting process, the anchor body also forms an enlarged diameter section, meaning the part of the stiffening pile inside the hole has an enlarged diameter, increasing the pull-out resistance of the stiffening pile. Stiffening piles are tensioned and fixed to the lattice beams. The stiffening piles effectively control the displacement and internal forces of the support structure, thereby effectively constraining slope deformation and reducing creep deformation. The capping beam, lattice beam, ground beam, and stiffening piles form the support structure for the high slope, while the retaining piles, capping beam, and anchoring devices form the support structure for the vertical excavation of the foundation pit. These two support structures together constitute the support structure for the high slope and the foundation pit, reducing the support depth of the retaining piles, the support length of the stiffening piles, and the construction difficulty, thus reducing the project cost.

[0040] This utility model is applicable to high slope support with limited land area, high slopes with buildings at the top that have high deformation requirements and limited construction space at the bottom, and can also be used for the prevention and control of shallow slopes, as well as slopes with gentle changes in slope ratio and little undulation. Attached Figure Description

[0041] Figure 1 This is an elevation view of one embodiment of the support structure for high slopes and foundation pits of this utility model.

[0042] Figure 2 This is a cross-sectional schematic diagram of one embodiment of the support structure for high slopes and foundation pits of this utility model.

[0043] Figure 3 This is a schematic diagram of the lattice beam and lattice panel in one embodiment of the support structure for high slopes and foundation pits of this utility model.

[0044] Figure 4 This is a schematic diagram of the tensioning and fixing of stiffening piles and lattice beams in one embodiment of the support structure for high slopes and foundation pits of this utility model.

[0045] Figure 5 This is a schematic elevation view of the support piles and the retaining wall between the piles in one embodiment of the support structure for high slopes and foundation pits of this utility model.

[0046] Figure 6 yes Figure 5 A plan view of the support piles and the retaining wall between the piles in the embodiment shown.

[0047] Figure 7 yes Figure 2 The diagram shows the structure of the anchoring device and the tensioning and fixing of the support pile in the embodiment shown.

[0048] Attached reference numerals: 1. Interception ditch; 2. Top beam; 3. Lattice beam; 4. Ground beam; 5. Stiffening pile; 5. Sludge section; 5a. Anchoring section; 5b. Anchor body; 5-1. Reinforcing bar; 5-2. Anchor plate; 5-3. Support pile; 6. Crown beam; 7. Anchoring device; 8. Anchor cable; 8-1. Stringing ring; 8-2. Hoop ring; 8-3. Pad; 8-4. Diagonal brace block; 8-5. Cover plate; 8-6. Bearing plate; 8-7. Anchor head; 8-8. Grouting pipe; 8-9. Drainage ditch; 9. Sealing anchor body; 10. Structural joint; 11. Lattice panel; 12. Pile wall protection; 13. Bottom elevation of foundation pit h1. Detailed Implementation

[0049] The present invention will be further described below with reference to the accompanying drawings.

[0050] The first subject of this utility model is the support structure for high slopes and foundation pits. For example... Figure 1 and Figure 2As shown, the support structure for the high slope and foundation pit includes a drainage ditch 1 and a capping beam 2 located at the top of the slope, a lattice beam 3 located on the slope surface, a ground beam 4 located at the bottom of the slope, and stiffening piles 5 inclined downwards within the slope body. The drainage ditch 1 is used to prevent surface runoff from entering the slope surface. The side of the drainage ditch 1 facing away from the slope surface is the non-construction area; for example, the side of the drainage ditch 1 facing away from the slope surface is the red line, and the side of the red line facing away from the drainage ditch 1 is farmland. The capping beam 2 is arranged along the top of the slope and connected to the vertical beams of the lattice beam 3 located on the slope surface. The cross-sectional dimensions of the capping beam 2 are determined according to the conditions of the high slope; for example, the cross-sectional dimensions of the capping beam 2 are 0.5m × 0.55m. The lattice beam 3 includes horizontal beams arranged horizontally and vertical beams perpendicular to the horizontal beams. The horizontal beams and vertical beams are cast integrally. The upper ends of each vertical beam are connected to the capping beam 2, and the lower ends of each vertical beam are connected to the ground beam 4. The stiffening pile 5 includes an anchor body 5-1 obtained by high-pressure jet grouting in the borehole, and reinforcing bars 5-2 embedded in the anchor body 5-1. The stiffening pile 5 serves two purposes: reinforcing the slope and fixing the lattice beam 3. Fixing holes are provided at the connections between the horizontal and vertical beams of the lattice beam 3, and the stiffening pile 5 corresponds one-to-one with each fixing hole. The upper end of the reinforcing bar 5-2 of the stiffening pile 5 passes through the fixing hole and is tensioned and fixed by anchors; that is, the upper end of the reinforcing bar 5-2 of the stiffening pile 5 is tensioned and fixed to the lattice beam 3. The capping beam 2, lattice beam 3, and ground beam 4 are all reinforced concrete structures and become a whole after casting. The capping beam 2, lattice beam 3, ground beam 4, and stiffening pile 5 form the support structure for the high slope.

[0051] The stiffening pile 5 serves a dual purpose: stabilizing the slope and tensioning the lattice beam 3. The construction of the stiffening pile 5 mainly involves two steps: first, hole drilling, which involves creating a hole in the rock mass at a certain angle using a down-the-hole drill; second, the jet grouting rig, carrying the reinforcing bar 5-2, enters the hole and performs high-pressure grouting. This means that while the jet grouting rig is entering the hole with the reinforcing bar 5-2, grouting reaches the bottom of the hole, and as the drill bit is withdrawn, high-pressure grouting is performed again around the hole. Structurally, see [link to relevant documentation]. Figure 4 The stiffening pile 5 is divided into a sedimentation section 5a and an anchorage section 5b from bottom to top. Reinforcing bars 5-2 are distributed throughout the anchorage section 5b. The reinforcing bars 5-2 are generally steel strands; for example, they may be 3φs 15.2mm low-relaxation, high-strength, fully bonded steel strands with a standard strength of 1860MPa. To ensure the reinforcing bars 5-2 are distributed close to the centerline of the hole, at least one anchor plate 5-3 is also spaced along the length of the stiffening pile 5. The anchor plate 5-3 has a through hole for the reinforcing bars 5-2 to pass through, and the reinforcing bars 5-2 penetrate the anchor plate 5-3 and are fixedly connected to it. For example, after the reinforcing bars 5-2 penetrate the anchor plate 5-3, the two are relatively fixed using nuts.

[0052] The stiffening piles 5 are arranged in a row-column matrix across the entire slope. To uniformly reinforce the entire slope, the length directions of each stiffening pile 5 are parallel to each other; for example, the length directions of each stiffening pile 5 are parallel to each other, and the acute angle formed with the horizontal line is 15°. To ensure that stiffening piles 5 at different heights can effectively anchor the lattice beam 3, the length of stiffening piles 5 exposed at higher positions is greater than that of stiffening piles 5 exposed at lower positions; that is, the higher the position of the stiffening pile 5 on the slope, the longer its length. For example, the length of the stiffening pile 5 ranges from 15.5 to 32.0 m. To prevent corrosion of the reinforcing bars 5-2 at the upper end of the stiffening piles 5 and the anchorages, a sealing anchor body 10 is provided at the fixing hole of the lattice beam 3 to seal the upper end of the reinforcing bars 5-2 and the anchorages. For example, the sealing anchor body 10 is a reinforced concrete structure, and the reinforcing bars of the sealing anchor body 10 are welded and fixed to the anchorages. The reinforcing bars of the sealing anchor body 10 are generally threaded steel bars, and the concrete of the sealing anchor body 10 is generally C30 concrete. After the stiffening pile 5 is tensioned and fixed, grouting needs to be added through the grouting holes on the steel pad, and then the construction of the sealing anchor body 10 should be carried out. The net protective layer thickness of the sealing anchor body 10 should not be less than 35mm. The exposed parts of the reinforcing bars 5-2 of the stiffening pile 5 and the steel pad should be derusted and painted with asphalt bottom paint before installation and locking. The exposed parts of the reinforcing bars 5-2 should preferably be cut with a hand-held cutting tool, and their exposed length should not be less than 50mm.

[0053] The lattice beam 3 is installed across the entire slope. To prevent structural damage to the lattice beam 3, it is provided with at least one structural joint 11. The plane corresponding to the structural joint 11 is a vertical plane, and filler is installed within the structural joint 11, such as... Figure 3 As shown. For example, structural joints 11 are set at horizontal intervals of approximately 20m in the lattice beam 3, and the structural joints 11 are filled with asphalt filler. To prevent rainwater from seeping into the slope from within the grid of the lattice beam 3, and also to prevent the slope within the grid of the lattice beam 3 from collapsing, lattice panels 12 are provided within the grid of the lattice beam 3. The lattice panels 12 include a steel mesh fixedly connected to the lattice beam 3, and a concrete slab formed by spraying concrete onto the steel mesh, such as... Figure 3 As shown. For example, the steel mesh of the lattice panel 12 is two layers, the concrete slab is 180mm thick and uses C25 concrete, and it is sprayed in two stages. In order to facilitate the drainage of water inside the slope through the slope surface, the lattice panel 12 is also provided with drainage holes, for example, the lattice panel 12 is provided with drainage holes at intervals of 2.0m.

[0054] At the bottom of the slope, support piles 6 are installed at intervals. The centerline of the support piles 6 is vertical and they are reinforced concrete structures. The side of the support piles 6 facing away from the slope is the excavation area of ​​the foundation pit. The support piles 6 are arranged at intervals. To ensure the safety of the foundation pit excavation, the lower end of the support pile 6 is lower than the bottom elevation h1 of the foundation pit, which is the elevation of the deepest excavation position of the foundation pit. Generally, the length of the support pile 6 below the bottom elevation h1 of the foundation pit is not less than the depth of the foundation pit. The upper ends of each support pile 6 are connected by a capping beam 7, so that the support piles 6 form a whole. Between the capping beam 7 and the ground beam 4 is a drainage ditch 9, which is used for drainage. For example, the drainage ditch 9 is connected to the drainage system and eventually discharges into the urban drainage network. After the foundation pit is excavated, in order to ensure the stability of the pit wall, a retaining wall 13 formed by shotcrete and wire mesh is used between two adjacent support piles 6. Figure 5 and Figure 6 As shown.

[0055] The upper end of the support pile 6 or the capping beam 7 is anchored to the slope via the anchoring device 8 to ensure the stability of the support pile 6 and the capping beam 7. The anchoring device 8 is used to fix the upper end of the capping beam 7 and the support pile 6. The anchoring device 8 includes grout injected into the anchor hole and anchor cables 8-1 embedded in the grout. For example, the anchor cables 8-1 are steel strands and there are at least two of them. The anchoring device 8 is divided into a free section and an anchoring section. The free section is provided with wire-laying rings 8-2 at intervals along its length. The wire-laying rings 8-2 are used to ensure that the anchor cables 8-1 are distributed along the center line of the anchor hole. The anchoring section is provided with wire-laying rings 8-2 and clamping rings 8-3 at intervals. The grouting pipe 8-9 and the anchor cable 8-1 pass through each wire-laying ring 8-2 and clamping ring 8-3, such as... Figure 7 As shown. The duct ring 8-2 ensures that the anchor cable 8-1 is distributed along the centerline of the anchor hole. The duct ring 8-2 and clamping ring 8-3 are spaced apart in the anchoring section, which helps improve the integrity of the anchor cable 8-1 and the grouting body, increases the pull-out resistance of the anchoring device 8, and also facilitates the insertion of the anchor cable 8-1 into the anchor hole. For example, in the anchoring section, the duct ring 8-2 and clamping ring 8-3 are spaced 0.70m apart; in the free section, a duct ring 8-2 is installed every 2.0m to ensure the straightness of the anchor cable 8-1. The anchoring device 8 is arranged inclined downwards, and the grouting body of the anchoring device 8 becomes a unified whole with the surrounding soil and rock mass of the anchor hole. To facilitate the installation of the anchoring device 8, the capping beam 7 or the support pile 6 is provided with a pre-drilled hole. This pre-drilled hole is used for the construction of the anchoring device 8. Since the anchoring device 8 is arranged at an angle downwards, to facilitate the tensioning and fixing of the anchor cable 8-1, the exposed end of the anchor cable 8-1 sequentially passes through the pre-drilled hole, the pad 8-4, the diagonal brace 8-5, the cover plate 8-6, and the bearing plate 8-7, and is then tensioned and fixed to the support pile 6 or the capping beam 7 via the anchoring head 8-8. Figure 7 As shown.

[0056] The second aspect of this utility model is a method for supporting high slopes and foundation pits, which is also the construction method of the first aspect mentioned above. The method for supporting high slopes and foundation pits includes the following steps.

[0057] S1. Construct intercepting ditch 1 at the top of the slope. The location and dimensions of intercepting ditch 1 shall be determined according to the design and terrain conditions.

[0058] S2. Excavate the soil at the top of the slope and construct the capping beam 2. The capping beam 2 is pre-reserved with reinforcing bars for connection with the vertical beams of the lattice beam 3. For example, the cross-sectional dimensions of the capping beam 2 are 550mm × 400mm.

[0059] S3. Excavate the slope layer by layer from top to bottom to the operating platform according to the designed slope ratio, and trim the slope surface. Slope excavation shall be carried out from top to bottom, removing loose rocks from the slope surface. To ensure safety, the excavation depth of each layer of earth and rock should not exceed 0.8m below the fifth hole of each row of stiffening piles. After excavating layer by layer to the operating platform according to the designed slope ratio, leave a 6m wide operating platform for mechanical construction. After smoothing the slope surface, proceed with the construction of the fifth stiffening pile.

[0060] S4. Construction of stiffening piles 5. First, determine the hole positions of stiffening piles 5 on the slope. The hole positions correspond one-to-one with the fixing holes of lattice beams 3 in step S5. Then, drill and clean the holes. The holes are arranged at an angle downward. Then, use a jet grouting drill to bring the reinforcing bars 5-2 into the hole, perform high-pressure jet grouting, and obtain the anchor body 5-1.

[0061] The drilling of stiffening pile 5 adopts a mechanical dry drilling process, such as using a down-the-hole drill (DHD) rig, specifically a 90-type DHD rig. To ensure the quality of the hole, casing should be used for wall protection when the hole wall stability is poor. After the DHD rig is fixed, the azimuth and inclination angles are adjusted, the drilling position is checked, and then all fasteners are tightened. Drilling can begin once everything is ready. After drilling is completed, the hole is blown out with high-pressure air; once the dust inside the hole is cleared and the hole depth meets the requirements, the drill rod and drill bit are pulled out.

[0062] The reinforcing bars 5-2 of a single stiffening pile 5 are often not a single bar, but multiple bars. For example, the reinforcing bars 5-2 use 3φs15.2mm low-relaxation, high-strength, fully bonded steel strands with a standard strength of 1860MPa. The processing length of the steel strands is strictly determined according to the drawings, and the steel strands should be cut using an abrasive saw. The reinforcing bars 5-2 include an anchorage section and an exposed section. To facilitate jack tensioning, the length of the exposed section of the reinforcing bars 5-2 should preferably be greater than 1.5m. To ensure that the stiffening piles 5 can provide sufficient pull-out force, the length directions of each stiffening pile 5 are parallel to each other. The length of the stiffening pile 5 with a higher exposed position is greater than the length of the stiffening pile 5 with a lower exposed position. The number and length of the steel strands of the stiffening piles 5 in the same row are consistent, that is, the number and length of the steel strands of the stiffening piles 1 at the same height are consistent.

[0063] To facilitate the simultaneous fixing of each reinforcing bar 5-2 of a single stiffening pile 5, at least one anchor plate 5-3 is installed at intervals along the length of the stiffening pile 5. Steel strands pass through the anchor plates 5-3 and are fixedly connected to them. A jet grouting drill is then used to bring the reinforcing bars 5-2 and the anchor plates 5-3 into the hole. For example, the hole diameter of the stiffening pile 5 is 180mm, the diameter of the anchor plate 5-3 is 150mm, and holes of 20mm diameter are evenly spaced on the anchor plate 5-3 according to the number of steel strands. After the steel strands pass through the holes in the anchor plate 5-3, they are fixed with nuts.

[0064] Before inserting the reinforcing bar 5-2 into the hole, first check whether the number of the stiffening pile 5 matches the hole number. After confirming that the hole depth and the length of the reinforcing bar 5-2 are correct, use a guide probe to probe the hole. If there is no obstruction, then use a jet grouting rig to bring the reinforcing bar 5-2 into the hole and perform high-pressure jet grouting. The pressure of high-pressure jet grouting depends on the geological properties, and the pressure is generally not less than 20 MPa. The water-cement ratio of the grout is generally 0.8:1.

[0065] After the down-the-hole drill rig breaks up and loosens the soil layer, the jet grouting rig advances, bringing in the reinforcing bar 5-2 to the designed depth. High-pressure jet grouting is then performed, where the grout directly impacts and cuts the soil and breaks up the rock mass. The grout mixes with soil particles and debris, solidifying to form an anchor body 5-1, which serves to replace, compact, and anchor, thus reinforcing the soil and rock mass. The anchor body 5-1 is generally M30. The shape of the anchor body 5-1 varies in different strata. By re-stirring and increasing the grout injection pressure, an enlarged diameter section is formed, meaning the portion of the anchor body 5-1 within the hole has an enlarged diameter, which increases the pull-out resistance of the stiffening pile 5. During the construction of the stiffening pile 5, the borehole diameter is 180mm, and the diameter of the anchor body 5-1 is generally 300-500mm, effectively reducing the stress level of the soil surrounding the stiffening pile and minimizing the plastic deformation of the reinforcing bar 5-2. Pre-tensioning the reinforcing bars 5-2 effectively controls the displacement and internal forces of the support structure, achieving effective constraint on deformation and reducing creep deformation. For rock slopes, the reinforcing bars 5-2 of the stiffening pile 5 can penetrate deep into the stable rock mass, connecting unstable rock blocks with the stable rock mass. Especially for rock slopes with joints and fissures, the reinforcing bars 5-2 can pass through the fissures, tightening the broken rock blocks and preventing them from falling.

[0066] To facilitate the subsequent construction of the lattice beam 3, after the high-pressure jet grouting pile is completed and before the grout solidifies, connecting reinforcing bars are inserted into the hole. Part of the connecting reinforcing bar is located inside the hole, and part is located outside. When tying the reinforcing bars of the lattice beam 3, the connecting reinforcing bars serve to initially fix the reinforcing bars of the lattice beam 3, and also improve the connection strength between the lattice beam 3 and the stiffening pile 5. For example, the total length of the connecting reinforcing bar is 1.50m, with 0.60m exposed, and a diameter of φ12mm.

[0067] S5. Construction of the lattice beam 3 and installation of the steel mesh for the lattice panel 12, including: erecting scaffolding → grooving the slope → fabricating and binding steel bars → installing formwork → pouring concrete and curing → removing formwork → tensioning and locking the stiffening piles 5 → cleaning loose soil and stones on the slope → hanging steel mesh on the slope → dismantling the scaffolding; wherein, fixing holes are reserved at the connection between the horizontal and vertical beams of the lattice beam 3, and the stiffening piles 5 correspond one-to-one with the fixing holes and are tensioned and fixed.

[0068] The lattice beam 3 includes horizontally arranged crossbeams and vertical beams perpendicular to them. The crossbeams and vertical beams are cast integrally, and the upper ends of each vertical beam are connected to the capping beam 2. The dimensions and spacing of the lattice beam 3 are determined according to the slope conditions; for example, the cross-sectional dimensions of the lattice beam 3 are 0.40 m × 0.55 m, and the spacing is 2.50 m × 2.50 m. Fixing holes are provided at the connections between the crossbeams and vertical beams of the lattice beam 3. Stiffening piles 5 correspond one-to-one with the fixing holes, and the upper ends of the reinforcing bars 5-2 of the stiffening piles 5 pass through the fixing holes and are tensioned and fixed by anchors. The tensioned and fixed reinforcing bars 5-2 and the lattice beam 3 form a comprehensive support system, improving the overall stability of the slope.

[0069] To prevent corrosion of the reinforcing bars 5-2 at the upper end of the stiffening pile 5 and the anchorage, after the construction of the first-layer lattice beam 3 is completed and the stiffening pile 5 is fixed by tensioning the anchorage, grouting needs to be added through the grouting holes on the steel pad of the anchorage. Then, a sealing anchor body 10 is constructed in the fixing hole to seal the upper end of the reinforcing bars 5-2 and the anchorage. For example, the sealing anchor body 10 is a reinforced concrete structure, and the reinforcing bars of the sealing anchor body 10 are welded and fixed to the anchorage.

[0070] S6. Shotcrete is applied within the grid of the lattice beam 3 to obtain the lattice panel 12. The lattice panel 12 includes a steel mesh fixedly connected to the lattice beam 3, and a concrete slab formed by shotcreting concrete onto the steel mesh, such as... Figure 3 As shown. For example, the steel mesh of the lattice panel 12 is two layers, the concrete slab is 150mm thick and uses C25 concrete, and it is sprayed in two stages, with a 25-ton crane used for the spraying operation. In order to facilitate the drainage of water inside the slope through the slope surface, the lattice panel 12 is also provided with drainage holes, for example, the lattice panel 12 is provided with drainage holes at intervals of 2.0m.

[0071] S7. Repeat steps S3 to S6 above until construction reaches the bottom of the slope.

[0072] The slope surface is large, and the lattice beam 3 is installed across the entire slope. To prevent structural damage to the lattice beam 3, in steps S3 and S7, the lattice beam 3 is provided with at least one structural joint 11. The plane corresponding to the structural joint 11 is a vertical plane, and filler is installed inside the structural joint 11, such as... Figure 3 As shown. For example, structural joints 11 are set at 20m intervals in the horizontal direction for the lattice beam 3, and the structural joints 11 are filled with asphalt filler.

[0073] S8. Construct ground beam 4 at the bottom of the slope, with the lower ends of all vertical beams connected to ground beam 4. After the construction of ground beam 4 is completed, the support of the entire high slope is finished.

[0074] S9. Construct drainage ditch 9 at the bottom of the slope. The slope earthwork is excavated to the bottom of the slope, and drainage ditch 9 is constructed at the toe of the slope. Drainage ditch 9 is connected to the drainage system and eventually flows into the urban drainage network.

[0075] S10. Construct support piles 6 at the bottom of the slope. The centerline of the support piles 6 is vertical and they are made of reinforced concrete. The lower end of the support piles 6 is lower than the bottom elevation h1 of the foundation pit.

[0076] The support piles 6 are spaced along the bottom of the slope, with the side of the support piles 6 facing away from the slope being the excavation area. For example, the diameter of the support piles 6 is 1.0m, and the pile spacing is 3.0m. Another example is that the support piles 6 are bored cast-in-place piles, with the holes formed using a rotary drilling machine, and the concrete strength grade of the pile body is C30. To ensure the safety of the excavation, the lower end of the support piles 6 is lower than the bottom elevation h1 of the pit, which is the elevation of the deepest excavation point. Generally, the pile holes for the support piles 6 are formed by a rotary drilling rig, and the length of the support piles 6 below the bottom elevation h1 of the pit is not less than the depth of the pit. When constructing the support pile 6, first determine the pile position by positioning and setting out lines. The support pile 6 is set in a row along the longitudinal direction. The rotary drilling rig is used to drill holes in a step-by-step manner. The drilling operation should be carried out continuously. After the hole is formed, the steel cage is hoisted and then the concrete is poured. The concrete of the pile body should be poured continuously in one go. Finally, the integrity of the pile body is tested.

[0077] S11. Construct the capping beam 7, and connect the upper ends of each support pile 6 through the capping beam 7.

[0078] The upper ends of each support pile 6 are connected by a capping beam 7, forming a unified whole. For example, the capping beam 7 has a cross-sectional dimension of 1.20m × 0.8m and is made of C30 reinforced concrete. A drainage ditch 9 connects the capping beam 7 and the ground beam 4. The drainage ditch 9 is used for drainage; for example, it connects to a drainage system, ultimately discharging into the city's drainage network. Construction of the capping beam 7 includes excavating the soil for the capping beam 7 → removing the laitance from the pile heads of the support piles 6 → tying the reinforcing steel bars of the capping beam 7 → installing and reinforcing the formwork → pouring the concrete for the capping beam 7 → curing and formwork removal.

[0079] For the construction of the support piles 6 and the capping beam 7, to facilitate the construction of the anchoring device 8, the upper end of the support piles 6 or the capping beam 7 is reserved with pre-drilled holes for constructing and fixing the anchoring device 8. For example, the pre-drilled holes are set when tying the reinforcing bars of the capping beam 7.

[0080] S12. Construction anchoring device 8, the anchoring device 8 is tensioned and fixed to the upper end of the support pile 6 or the capping beam 7.

[0081] The anchoring device 8 is mainly used to fix the upper ends of the cap beam 7 and the support piles 6. The anchoring device 8 includes grout injected into the anchor hole and anchor cables 8-1 embedded in the grout. For example, the anchor cables 8-1 are steel strands and there are at least two of them. The anchoring device 8 is divided into a free section and an anchoring section. The structure of the anchoring device 8 is the same as the relevant description in the first topic, and will not be repeated here. When the anchor cables 8-1 are steel strands, the steel strands need to be degreased and derusted in advance, the free section should be coated with grease, and anti-slip pipes should be fitted. Sufficient tensioning sections should be reserved outside the anchor hole, and the excess parts can be cut off after the foundation pit is stabilized. To improve the pull-out resistance of the anchoring device 8, two grouting pipes 8-9 are used for the construction of the anchoring device 8, and high-pressure grouting is carried out in two stages into the anchor hole, that is, secondary grouting is adopted. For example, the grouting pressure is 0.20~0.50MPa, and the grout is M30 cement grout with a water-cement ratio of 0.50~0.55. After inserting the device, including anchor cable 8-1, overhead wire ring 8-2, clamping ring 8-3, wall protection guide, guide cap, and grouting pipe 8-9, into the anchor hole, a grout-stopping ring is installed at the junction of the free section and the anchoring section. The first grouting begins, and the wall protection guide is pulled out while grouting. Grouting is stopped after the cement grout overflows from the hole. After grouting, when the grout level drops, grouting should be added to the hole. After the grout's consolidation strength reaches 5 MPa, a second grouting is performed. The grouting pipe 8-9 used for the second grouting should be firmly tied to the device, and the grouting termination pressure should not be less than 1.5 MPa.

[0082] Anchoring device 8 is arranged at an angle downwards, and the grouting body of anchoring device 8 becomes a whole with the surrounding soil and rock. For example, the direction of anchoring device 8 is consistent with the direction of stiffening pile 5, and anchoring device 8 is anchored into the original soil around the foundation pit at an angle of 15°. In order to facilitate the arrangement of anchoring device 8, the capping beam 7 or the support pile 6 is provided with reserved holes for the construction of anchoring device 8. For example, the capping beam 7 is provided with reserved holes. Drill rods are inserted into the reserved holes of capping beam 7, the drill rods are fixed to the drilling rig, the azimuth and inclination angles are adjusted, and then all fasteners are tightened. After the drilling is completed, the hole is blown with high air pressure. When the dust in the hole is blown away and the hole depth reaches the required level, the drill rods and drilling tools are pulled out, and the above-mentioned device is inserted into the anchor hole. Then, high-pressure grouting is performed. After the grout reaches 75% strength, the anchor cable 8-1 is tensioned and fixed. Because the anchoring device 8 is arranged at an angle downwards, in order to facilitate the tensioning and fixing of the anchor cable 8-1, the exposed end of the anchor cable 8-1 passes through the reserved hole, the pad plate 8-4, the diagonal brace block 8-5, the cover plate 8-6, and the bearing plate 8-7 in sequence, and is tensioned and fixed to the support pile 6 or the cap beam 7 through the anchoring head 8-8. Figure 7 As shown.

[0083] S13. Excavate the foundation pit in layers and support the pit walls between the support piles 6.

[0084] After the anchoring device 8 is tensioned and fixed to the support pile 6 or the cap beam 7, the foundation pit is excavated. The foundation pit is excavated vertically downwards in layers, and the foundation pit wall is trimmed simultaneously. A mesh is then hung between two adjacent support piles 6 and shotcrete is applied to form an inter-pile retaining wall 13. Figure 5 and Figure 6 As shown. In order to ensure the stability of the steel mesh of the pile retaining wall 13, connecting steel bars are inserted into the support piles 6, and the steel mesh of the pile retaining wall 13 is connected to the connecting steel bars.

Claims

1. A supporting structure for high slope and foundation pit, comprising a cut-off trench (1) and a pressure roof beam (2) located at the top of the slope, a lattice beam (3) located on the slope surface, a ground beam (4) located at the bottom of the slope, and a reinforced pile (5) which is inclined downwardly and arranged in the slope body, characterized in that: The reinforced pile (5) comprises an anchoring body (5-1) obtained by high-pressure jet grouting in a hole, and a stress bar (5-2) embedded in the anchoring body (5-1); the lattice beam (3) comprises horizontal beams arranged in the horizontal direction and vertical beams perpendicular to the horizontal beams, upper ends of each vertical beam are connected with the coping beam (2) respectively, lower ends of each vertical beam are connected with the ground beam (4) respectively, the coping beam (2), the lattice beam (3) and the ground beam (4) are all reinforced concrete structures, fixed holes are arranged at connecting positions of the horizontal beams and the vertical beams, the reinforced pile (5) corresponds to the fixed holes one by one, upper ends of the stress bars (5-2) of the reinforced piles (5) penetrate the fixed holes and are fixed by anchoring devices, and the slope bottom is further provided with support piles (6) at intervals, center lines of the support piles (6) are vertical and the support piles (6) are reinforced concrete structures, one side of the support piles (6) facing away from the slope body is a foundation pit excavation area, lower ends of the support piles (6) are lower than the elevation (h1) of the bottom of the foundation pit, upper ends of each support pile (6) are connected through a corbel beam (7), the upper ends of the support piles (6) or the corbel beam (7) are anchored to the slope body through anchoring devices (8), and a drainage ditch (9) is arranged between the corbel beam (7) and the ground beam (4).

2. The supporting structure for high slope and foundation pit according to claim 1, wherein: The fixed holes of the lattice beam (3) are further provided with an anchoring sealing body (10) for sealing the upper ends of the stress bars (5-2) and the anchoring devices.

3. The supporting structure for high slope and foundation pit according to claim 1, wherein: The anchoring sealing body (10) is a reinforced concrete structure, and the reinforcing steel bars of the anchoring sealing body (10) are welded and fixed with the anchoring devices.

4. The supporting structure for high slope and foundation pit according to claim 1, wherein: The lattice beam (3) is provided with at least one structural joint (11), a plane corresponding to the structural joint (11) is a vertical plane, and the structural joint (11) is filled with asphalt filler.

5. The supporting structure for high slope and foundation pit according to claim 1, wherein: The reinforced pile (5) is divided into a sedimentation section (5a) and an anchoring section (5b) from bottom to top, the stress bar (5-2) of the reinforced pile (5) is a steel strand, the steel strand is distributed in the entire anchoring section (5b), and at least one anchor disc (5-3) is further arranged in the length direction of the reinforced pile (5), the steel strand penetrates the anchor disc (5-3) and is fixedly connected with the anchor disc (5-3).

6. The supporting structure for high slope and foundation pit according to claim 1, wherein: The length directions of the reinforced piles (5) are parallel to each other, the length of the reinforced pile (5) exposed at a high position is greater than the length of the reinforced pile (5) exposed at a low position.

7. The supporting structure for high slope and foundation pit according to claim 1, wherein: The lattice beam (3) is provided with a lattice panel (12) in a grid, the lattice panel (12) comprises a steel mesh fixedly connected with the lattice beam (3) and a concrete plate formed by spraying concrete to the steel mesh, and the lattice panel (12) is further provided with a water drainage hole.

8. The supporting structure for high slope and foundation pit according to claim 1, wherein: The length of the support pile (6) below the elevation (h1) of the bottom of the foundation pit is not less than the depth of the foundation pit, and lattice panels (12) formed by spraying concrete to a net are arranged between adjacent two support piles (6).

9. The supporting structure for high slope and foundation pit according to any one of claims 1 to 8, characterized in that: The anchoring device (8) comprises a grouting body grouted in an anchor hole and an anchor cable (8-1) embedded in the grouting body, the anchor cable (8-1) is a steel strand and at least two, the anchoring device (8) is divided into a free section and an anchoring section, the free section is provided with a wire frame ring (8-2) at intervals in the length direction, the anchoring section is provided with the wire frame ring (8-2) and a clamping ring (8-3) at intervals, and a grouting pipe (8-9) and the anchor cable (8-1) penetrate each wire frame ring (8-2) and clamping ring (8-3).

10. The supporting structure for high slope and foundation pit according to claim 9, wherein: The anchoring device (8) is arranged obliquely downward, the crown beam (7) or the support pile (6) is provided with a reserved hole, the exposed end of the anchor cable (8-1) penetrates the reserved hole, the pad (8-4), the inclined support block (8-5), the cover plate (8-6) and the pressure bearing plate (8-7) in sequence, and is fixed by tension with the support pile (6) or the crown beam (7) through the anchoring head (8-8).

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