Red sandstone foundation pit multi-layer composite supporting structure

Abstract

The utility model discloses a red sandstone foundation pit multi-layer composite supporting structure, which belongs to the technical field of foundation pit supporting and comprises protective frames, anchor rods, surface layer steel bar hanging nets and surface layer concrete, the protective frames are arranged in a cross shape, mounting holes are formed in the centers of the protective frames, and the protective frames are arranged in an array and connected through connecting structures. Forming an inner protective net layer; the anchor rod comprises an outer anchor pipe and an inner anchor rod which are coaxially arranged, a plurality of anchor nails are arranged on the side wall of the outer anchor pipe in a radial sliding mode, and an abutting structure used for controlling the anchor nails to stretch out and draw back is arranged between the inner anchor rod and the anchor nails. The surface layer steel bar hanging net is formed by alternately distributing a plurality of steel bars. According to the multi-layer composite supporting structure of the red sandstone foundation pit, the outer anchor pipe and the inner anchor rod which are coaxial are arranged, and the anchor nails are driven to extend outwards and penetrate into the rock stratum in the radial direction through displacement of the inner anchor rod, so that the connecting strength of the anchor rods and the rock mass of the foundation pit is improved, and the stability of the supporting structure is guaranteed.

Description

Technical Field

[0001] This utility model belongs to the field of foundation pit support technology, and in particular relates to a multi-layer composite support structure for red sandstone foundation pits. Background Technology

[0002] Excavation pit support is an indispensable part of modern construction. Its core purpose is to ensure the safety of underground structure construction and protect the surrounding environment from potential threats posed by construction activities. Especially under complex geological conditions, such as excavation pits located within red sandstone layers, the rational design and implementation of support structures are of paramount importance.

[0003] The rapid weathering and easy softening and disintegration of exposed red sandstone layers make the design and implementation of support schemes extremely complex and risky. Existing support technologies, especially those relying on anchor bolt fixation, often suffer from insufficient connection strength due to the abundance and rapid infiltration of fissure water in the red sandstone layers. This makes it difficult to support the stability of the entire support structure. In addition, the dense surrounding buildings and their proximity to the foundation pit further increase the construction difficulty and safety risks.

[0004] To address these issues, we propose a multi-layer composite support structure for red sandstone foundation pits. Utility Model Content

[0005] The purpose of this invention is to solve the problem that the existing anchor-fixed soil nail wall support structure is not strong enough for red sandstone geology, and often fails to meet the support stability requirements. Therefore, this invention proposes a multi-layer composite support structure for red sandstone foundation pits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A multi-layer composite support structure for red sandstone foundation pits includes:

[0008] The protective frame is arranged in a cross shape and has a mounting hole at the center of the protective frame. Multiple protective frames are arranged in an array and connected by a connecting structure to form an inner protective mesh layer.

[0009] An anchor rod is inserted into the mounting hole. The anchor rod includes an outer anchor tube and an inner anchor rod arranged coaxially. Multiple anchor pins are radially slidably arranged on the side wall of the outer anchor tube. A pressure structure for controlling the extension and retraction of the anchor pins is provided between the inner anchor rod and the anchor pins.

[0010] The surface layer of steel reinforcement mesh is formed by alternating distribution of multiple steel bars;

[0011] The surface concrete and shotcrete are applied to the red sandstone foundation pit wall up to the surface steel reinforcement mesh.

[0012] Preferably, the protective frame is welded from C-shaped channel steel, and the concave surface of the protective frame faces the pit wall.

[0013] Preferably, the protective frame has multiple seepage holes equidistantly spaced on the side close to the pit wall.

[0014] Preferably, the connection structure includes connection holes opened at four extended ends of the protective frame, and the connection holes of two adjacent protective frames are coaxially arranged and cooperate to insert drainage connectors.

[0015] Preferably, the drainage connector includes a drainage pipe and a cap disposed at the end of the drainage pipe. The cap is hollow and has multiple water inlet grooves. The cap is disposed on the side of the protective frame near the foundation pit wall, and the drainage pipe extends to the outside of the surface concrete.

[0016] Preferably, the pressure-blocking structure includes a nut threaded onto the inner anchor rod, the nut abutting against the outer anchor tube, the inner anchor rod having multiple mounting cavities corresponding to the anchor nails, the mounting cavities having obliquely arranged pressure-blocking grooves, and the anchor nail having a pressure-blocking column adapted to the pressure-blocking groove installed at one end of the mounting cavity.

[0017] Preferably, the top of the inner anchor rod is equipped with a fixing block with a cross-shaped perforation, and the reinforcing bar is inserted into the cross-shaped perforation of the fixing block.

[0018] In summary, the technical effects and advantages of this utility model are as follows: This multi-layer composite support structure for red sandstone foundation pits, by setting coaxial outer anchor pipes and inner anchor rods, allows the anchor bolts to extend outwards during installation through the displacement of the inner anchor rods, penetrating the rock strata radially along the outer anchor pipes, thereby improving the connection strength between the anchor rods and the foundation pit rock mass and ensuring the stability of the support structure.

[0019] By setting up a protective frame with seepage holes, an inner protective mesh layer is formed when the frame is in close contact with the pit wall. Combined with the surface steel mesh woven with steel bars, after the surface concrete is sprayed, it achieves the effect of multi-layer composite support, which effectively improves the strength of the surface concrete. Furthermore, seepage water between the surface concrete and the pit wall can enter the inner side of the protective frame through the seepage holes and be discharged through the drainage connectors, avoiding the risk of water seepage at the top of the red sandstone layer causing difficulty in support or cracking or even bulging and falling off of the surface concrete. Attached Figure Description

[0020] Figure 1 This is a structural schematic diagram of the support configuration of this utility model;

[0021] Figure 2 This is a schematic diagram of the overall structure of this utility model;

[0022] Figure 3 This is a schematic diagram of the protective frame in this utility model;

[0023] Figure 4 This is a schematic diagram of the anchor rod structure in this utility model;

[0024] Figure 5 This is a schematic diagram of the drainage connector in this utility model;

[0025] Figure 6 This is a schematic diagram of the retracted anchor bolt structure of this utility model;

[0026] Figure 7 This is a schematic diagram of the protruding anchor bolt of this utility model;

[0027] Figure 8 for Figure 6 A magnified structural diagram of part A in the middle.

[0028] In the diagram: 1. Protective frame; 11. Mounting hole; 12. Water seepage hole; 13. Connection hole; 2. Anchor rod; 21. Outer anchor pipe; 22. Inner anchor rod; 221. Mounting cavity; 222. Pressure groove; 223. Fixing block; 23. Anchor nail; 231. Pressure column; 3. Surface steel reinforcement mesh; 31. Steel reinforcement; 4. Surface concrete; 5. Drainage connector; 51. Drainage pipe; 52. End cap; 53. Water inlet trough. Detailed Implementation

[0029] Reference Figure 1-5 A multi-layer composite support structure for red sandstone foundation pits includes a protective frame 1, anchor bolts 2, surface steel mesh 3, and surface concrete 4. Multiple protective frames 1 are spliced ​​together to form an inner protective mesh layer that fits the inner wall of the foundation pit. The surface concrete 4 is sprayed to cover the surface steel mesh 3, and together with the surface steel mesh 3, a multi-layer support structure is formed to ensure the stability of the foundation pit support.

[0030] The protective frame 1 is arranged in a cross shape, with an installation hole 11 at the center of the protective frame 1. Anchor rods 2 are inserted into the installation hole 11 to fix the protective frame 1 to the pit wall. Specifically, holes are drilled in the pit wall, and after the installation hole 11 is aligned with the drilled hole, the anchor rods 2 are inserted to achieve fixation. Multiple protective frames 1 are arranged in an array and connected by a connecting structure to form an inner protective mesh layer.

[0031] Reference Figure 1-5 The connection structure includes connection holes 13 at four extended ends of the protective frame 1. The connection holes 13 of two adjacent protective frames 1 are coaxially arranged and cooperate to insert drainage connectors 5. The protective frames 1 are connected through the drainage connectors 5. The drainage connectors 5 include a drain pipe 51 and a cap 52 set at the end of the drain pipe 51. The drain pipe 51 passes through the connection holes 13 of two protective frames 1. The diameter of the cap 52 is larger than the diameter of the connection hole 13 and is located inside the protective frame 1 to prevent the drain pipe 51 from detaching from the connection hole 13.

[0032] Reference Figure 1-5The protective frame 1 is welded from C-shaped channel steel, with its concave surface facing the pit wall. The protective frame 1 fits snugly against the pit wall to form a drainage channel. Multiple seepage holes 12 are equidistantly spaced on the side of the protective frame 1 closest to the pit wall. Water seeping between the surface concrete 4 and the pit wall seeps into the drainage channel through the seepage holes 12. The seepage flows along the drainage channel to the connection point of the protective frame 1, where the drainage connector 5 discharges the surface concrete 4. Specifically, the end cap 52 is hollow and has multiple water inlet grooves 53. The end cap 52 is located on the side of the protective frame 1 closest to the pit wall, and the drainage pipe 51 extends to the outside of the surface concrete 4. Seepage will flow through... The water enters the drainage pipe 51 through the inlet channel 53 and finally exits the surface concrete 4 through the drainage pipe 51. To ensure smooth drainage, the drainage pipe 51 can be installed perpendicular to the pit wall when installed in a vertical pit. When installed in a sloping pit, the drainage pipe 51 can be installed at an angle so that the drainage end of the drainage pipe 51 is lower than the end cap 52. When installing the protective frame 1, the four arms of the protective frame 1 need to be installed at an angle to ensure that the water seeps into the guide channel and flows downward along the guide channel under the action of gravity to collect, avoiding the risk of water seepage at the top of the red sandstone layer causing difficulty in support or cracking or even bulging and falling off of the surface concrete 4.

[0033] Reference Figure 4-8 The anchor rod 2 includes an outer anchor tube 21 and an inner anchor rod 22 arranged coaxially. Multiple anchor nails 23 are radially slidably arranged on the side wall of the outer anchor tube 21. A pressure structure for controlling the extension and retraction of the anchor nails 23 is provided between the inner anchor rod 22 and the anchor nails 23. During installation, the anchor nails 23 are completely inside the outer anchor tube 21. After the anchor rod 2 is installed into the borehole in the foundation pit wall, the pressure structure controls the anchor nails 23 to extend outward and penetrate into the rock strata of the foundation pit wall, thereby increasing the circumferential friction between the anchor rod 2 and the borehole, and thus increasing the connection strength between the anchor rod 2 and the foundation pit rock mass, ensuring the stability of the support structure.

[0034] Reference Figure 6-8 The anti-pressure structure includes a nut 24 threaded onto the inner anchor rod 22, which abuts against the outer anchor tube 21. Rotating the nut 24 can drive the inner anchor rod 22 to move axially. The inner anchor rod 22 has multiple mounting cavities 221 corresponding to the anchor nails 23. The mounting cavities 221 have obliquely arranged anti-pressure grooves 222. An anti-pressure column 231 adapted to the anti-pressure groove 222 is installed at one end of the anchor nail 23 located in the mounting cavity 221. When the axis of the inner anchor rod 22 moves, the anti-pressure groove 222 moves synchronously, and the relative position of the anti-pressure groove 222 and the anchor nail 23 changes. The anti-pressure column 231 will move along the anti-pressure groove 222. Since the anti-pressure groove 222 is inclined, it will push the anti-pressure column 231 to move, causing the anchor nail 23 to move radially along the outer anchor tube 21, thus achieving expansion and contraction.

[0035] The surface layer steel reinforcement mesh 3 is formed by multiple steel bars 31 distributed alternately. The intersections of the steel bars 31 are fixed by binding with wire to make the steel bars 31 form a whole.

[0036] Reference Figure 1-2 The top of the inner anchor rod 22 is equipped with a fixing block 223 with a cross-shaped perforation. The reinforcing bar 31 is inserted into the cross-shaped perforation of the fixing block 223. The insertion of the reinforcing bar 31 into the fixing block 223 can also limit the circumferential positioning of the inner anchor rod 22, which is convenient for the locking of the nut 24. As the nut 24 is locked and the anchor nail 23 penetrates the rock layer, the outer anchor pipe 21, the inner anchor rod 22 and the anchor nail 23 are tightened together. The inner anchor rod 22 will extend outward by a certain length. The reinforcing bar 31 is inserted into the fixing block 223, which increases the distance between the surface steel mesh 3 and the foundation pit wall. This allows the surface concrete 4 to fully cover the surface steel mesh 3 to form a high-strength reinforced concrete structure. When the surface concrete 4 is subjected to deformation and compression by the foundation pit geology, the force is transmitted to the inner anchor rod 22 through the reinforcing bar 31 and acts on the anchor rod 2, achieving a good support effect.

[0037] The surface concrete 4 is sprayed from the red sandstone foundation pit wall to the covering surface steel mesh 3. The surface concrete 4 uses C20 fine stone concrete and the spray thickness is 80mm.

[0038] Working principle:

[0039] When carrying out foundation pit support, vertical layering and horizontal segmentation are carried out. The excavation height of each layer is 1.5m below the previous support surface. The length of the horizontal segment is determined according to the on-site construction speed. First, holes are drilled on the foundation pit wall. The drilling position is measured to ensure that adjacent protective frames 1 can be connected. After the installation hole 11 is aligned with the drilling hole, the anchor rod 2 is inserted. Multiple protective frames 1 are arranged in an array and connected by a connecting structure to form an inner protective net layer.

[0040] The reinforcing bars 31 are inserted into the cross-shaped holes of the fixing block 223. Multiple reinforcing bars 31 are alternately distributed to form a whole. The intersections of the reinforcing bars 31 are fixed by binding with wire to form a whole. When the nut 24 is rotated, the inner anchor rod 22 moves outward under the action of the thread, pushing the reinforcing bars 31 away from the pit wall, so that a gap is formed between the surface layer of reinforcing mesh 3 and the pit wall. At the same time, when the axis of the inner anchor rod 22 moves, the pressure groove 222 moves synchronously. The relative position of the pressure groove 222 and the anchor nail 23 changes, and the pressure column 231 moves along the pressure groove 222. Since the pressure groove 222 is inclined, the pressure groove 222 pushes the pressure column 231 to move, so that the anchor nail 23 moves radially along the outer anchor tube 21 and penetrates into the rock layer of the pit, realizing the stable connection between the anchor rod 2 and the pit wall.

[0041] The surface concrete 4 is formed by spraying concrete onto the foundation pit wall. The surface concrete 4 is sprayed to cover the surface steel mesh 3. The surface concrete 4 is made of C20 fine stone concrete and the spraying thickness is 80mm.

Claims

1. A multi-layer composite support structure for red sandstone foundation pits, characterized in that, include: The protective frame (1) is arranged in a cross shape and has a mounting hole (11) at the center of the protective frame (1). Multiple protective frames (1) are arranged in an array and connected by a connecting structure to form an inner protective mesh layer. An anchor rod (2) is inserted into the mounting hole (11). The anchor rod (2) includes an outer anchor tube (21) and an inner anchor rod (22) arranged coaxially. Multiple anchor nails (23) are radially slidably arranged on the side wall of the outer anchor tube (21). A pressure structure for controlling the extension and retraction of the anchor nails (23) is provided between the inner anchor rod (22) and the anchor nails (23). The surface layer steel reinforcement mesh (3) is formed by alternating distribution of multiple steel bars (31); The surface concrete (4) is sprayed onto the red sandstone foundation pit wall up to cover the surface steel reinforcement mesh (3).

2. The multi-layer composite support structure for red sandstone foundation pits according to claim 1, characterized in that, The protective frame (1) is welded from C-shaped channel steel, and the concave surface of the protective frame (1) faces the pit wall.

3. The multi-layer composite support structure for red sandstone foundation pits according to claim 2, characterized in that, The protective frame (1) has multiple seepage holes (12) at equal intervals on one side close to the foundation pit wall.

4. The multi-layer composite support structure for red sandstone foundation pits according to claim 2, characterized in that, The connection structure includes connection holes (13) opened at four extended ends of the protective frame (1). The connection holes (13) of two adjacent protective frames (1) are coaxially arranged and cooperate to insert drainage connectors (5).

5. A multi-layer composite support structure for red sandstone foundation pits according to claim 4, characterized in that, The drainage connector (5) includes a drainage pipe (51) and a cap (52) disposed at the end of the drainage pipe (51). The cap (52) is hollow and has multiple water inlet grooves (53). The cap (52) is disposed on the side of the protective frame (1) near the pit wall, and the drainage pipe (51) extends to the outside of the surface concrete (4).

6. The multi-layer composite support structure for red sandstone foundation pits according to claim 1, characterized in that, The pressure-blocking structure includes a nut (24) threaded onto the inner anchor rod (22), the nut (24) abutting against the outer anchor tube (21), the inner anchor rod (22) having multiple mounting cavities (221) corresponding to the anchor nails (23), the mounting cavity (221) having an obliquely arranged pressure-blocking groove (222), and the anchor nail (23) having a pressure-blocking column (231) adapted to the pressure-blocking groove (222) installed at one end of the mounting cavity (221).

7. The multi-layer composite support structure for red sandstone foundation pits according to claim 1, characterized in that, The top of the inner anchor rod (22) is fitted with a fixing block (223) with a cross-shaped perforation, and the reinforcing bar (31) is inserted into the cross-shaped perforation of the fixing block (223).

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