Steel shield protection mechanism and shallow covering soil underneath crossing roadbed construction method

Abstract

The invention relates to the technical field of road construction, in particular to a steel shield protection mechanism and a shallow covering soil underneath crossing roadbed construction method, and the steel shield protection mechanism comprises a reinforcing mesh, a grouting hole, an anchor rod and an anchor rod calibration structure; mainly through the arranged anchor rod calibration structure, when the anchor rod is laid, the anchor rod can be calibrated and installed at the center position of a grouting hole, the construction quality of the anchor rod is guaranteed, then the pit entering protection quality is guaranteed, through the arranged supporting assembly, the supporting assembly can be used in cooperation with the anchor rod calibration structure, the construction stability of the anchor rod is enhanced, and the construction efficiency is improved. The positive effect is achieved on foundation pit protection in overall steel shield protection construction; and the adaptive construction method is designed, so that the interference on the road in the construction process is small, and the actual construction requirements can be better met.

Description

Technical Field

[0001] The invention relates to the technical field of road construction, in particular to a steel shield protection mechanism and a shallow soil-covered underpass roadbed construction method. Background Art

[0002] The existing document with announcement number CN110107303A discloses a deformation control method for a shallow earth shield tunnel passing under a high-speed railway, which includes constructing a protective steel temporary bridge, constructing an isolation strip foundation and implementing shield reinforcement measures; the scheme adopts an isolation strip foundation, supplemented by a protective steel temporary bridge and a series of shield reinforcement measures to achieve deformation control of a shallow earth shield tunnel passing under a high-speed railway. The railway track is supported by the steel temporary bridge, which increases the track stiffness of the existing high-speed railway and reduces the adverse effects of the shield construction below. Through the implementation of the isolation strip foundation, the mutual influence between the existing high-speed railway and the shield tunnel is isolated, and at the same time, it plays a role in reinforcing the roadbed soil.

[0003] The shield construction protection in the above scheme is relatively weak. The existing shield protection construction, according to actual construction needs, generally requires working pit construction to strengthen and stabilize the pit slope of the foundation pit, thereby improving the overall construction protection performance; for slope protection construction, mesh spraying and concrete slope protection is generally used. When laying anchor rods, the anchor rods need to be laid in the grouting holes on the pit slope, and it is necessary to ensure that the anchor rods are in the center of the grouting holes. In this process, it is difficult to ensure the laying quality of the anchor rods, and there is a lack of suitable auxiliary mechanisms to meet the laying requirements of the anchor rods, which has a negative impact on the overall protection construction quality.

[0004] To this end, the present invention proposes a steel shield protection mechanism and a shallow soil-covered underpass roadbed construction method to solve the above problems. Summary of the Invention

[0005] The object of the present invention is to provide a steel shield protection mechanism and a shallow soil-covered underpass roadbed construction method to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a steel shield protection mechanism, comprising a steel mesh, grouting holes, anchor rods and an anchor rod calibration structure; the steel mesh is laid on a foundation pit slope, grouting holes are evenly spaced on the foundation pit slope, anchor rods are arranged in the grouting holes, and the anchor rods are calibrated by the anchor rod calibration structure.

[0007] Preferably, the anchor calibration structure includes a carrying ring, a fixing cylinder, a calibration threaded column, a rotating screw head, a connecting threaded cone, a accommodating cover, a limiting inner ring, an auxiliary ball, an internal threaded driving ring, an auxiliary handle, an arc-shaped auxiliary inclined groove, an annular accommodating cavity, a transmission bar, a support block, a connecting spring, and a connecting threaded groove body; the carrying ring is fixedly provided with a fixing cylinder, and the fixing cylinder is equidistantly threadedly connected with a calibration threaded column, one end of the calibration threaded column is fixedly provided with a rotating screw head, and the other end of the calibration threaded column is fixedly provided with a connecting threaded cone, and the connecting threaded cone is threadedly connected to the accommodating cover, and one end of the accommodating cover is fixedly provided with a limiting inner ring, and an auxiliary ball is placed in the accommodating cover. An annular accommodating cavity is provided in the carrying ring, and an internal thread driving ring is provided in the annular accommodating cavity for matching threaded connection. An auxiliary handle is symmetrically fixed on the internal thread driving ring, and an arc-shaped auxiliary inclined groove is equidistantly provided at the bottom end of the internal thread driving ring. The transmission bar is equidistantly movably provided in the carrying ring, one end of the transmission bar extends into the arc-shaped auxiliary inclined groove, and a support block is fixedly provided at the other end of the transmission bar. The support block is equidistantly movably provided in the placement groove, and the placement groove is provided in the carrying ring. A connecting spring is fixedly provided at one end of the support block connected to the transmission bar, and the other end of the connecting spring is fixedly provided in the placement groove. A connecting thread groove body is provided on the support block.

[0008] Preferably, the calibration threaded columns are arranged in three groups at equal intervals on the fixing cylinder.

[0009] Preferably, the number of groups of the internal thread drive ring and the load-bearing ring is the same.

[0010] Preferably, the support blocks and the transmission bars are provided at corresponding positions and are provided in the same number of groups; the transmission bars and the arc-shaped auxiliary inclined grooves are provided at corresponding positions and are provided in the same number of groups.

[0011] Preferably, the thickness of the transmission bar is smaller than the depth of the arc-shaped auxiliary inclined groove, and the end of the transmission bar extending to the arc-shaped auxiliary inclined groove is configured as an arc-shaped surface.

[0012] Preferably, when auxiliary support of the anchor rod is required, support is provided by a support assembly, which includes a connecting foot plate, a mounting hole, a support rod body, a circular hole, a fastening anchor nail, and a cap; one end of the support rod body is fixedly provided with a connecting foot plate, and the other end of the support rod body is fixedly provided with a flat plate, the connecting foot plate is provided with a mounting hole, and the connecting foot plate is fixedly connected to the support block by a screw, a circular hole is provided on the flat plate, and one end of the fastening anchor nail is fixedly provided with a cap.

[0013] Preferably, the support rods and support blocks are arranged at corresponding positions and in the same number of groups.

[0014] A shallow soil-covered underpass roadbed construction method comprising:

[0015] Foundation pit construction:

[0016] 1. Determine the slope top excavation line and the size of the working foundation pit based on the on-site soil quality and the designed bottom elevation and plane dimensions of the box body. The working pit is located on the east side of the highway, with a size of 43.5*66m, and uses two-level slope excavation.

[0017] Second, the side slopes near the highway must be manually brushed to ensure the stability and compactness of the roadbed slope soil. The excavation of the other three side slopes must also ensure that the plane is complete, with no vertical bumps or irregularities such as arcs in the horizontal direction.

[0018] 3. Steel bars and shotcrete are hung on the slope of the working pit. The concrete grade is C20. Drainage ditches are set up around the working pit to guide the water flow into the collection pit and pump it out in time. Intercepting ditches are set up around the top of the working pit to intercept rainwater from flowing into the working pit.

[0019] 4. After the foundation pit is excavated, the construction of the slide plate and back seat should be carried out as soon as possible to make the foundation pit completely closed and avoid being soaked by rainwater;

[0020] Hanging mesh sprayed concrete slope protection construction

[0021] The mesh spraying support should be closely coordinated with the foundation pit excavation, and each process should be carried out in parallel and in an orderly manner;

[0022] 1. Construction sequence of anchor and shotcrete support: slope repair → line setting → drilling → anchor rod installation → grouting → steel mesh hanging → reinforcement welding → shotcrete spraying;

[0023] 2. Drilling anchor holes: Use a drilling rig to drill holes. Measure and draw lines at 1.5m×1.5m intervals according to the designed hole positions. Mark the exact hole positions. Then drill holes according to the designed hole length, hole depression angle, and hole diameter. Pay strict attention to quality and record the acceptance of each hole. Unqualified holes will be deemed as waste holes and must be re-drilled. The anchor holes are arranged in a plum blossom shape, and the depression angle can be adjusted according to actual conditions.

[0024] 3. Anchor bolt installation: according to the length and diameter of the anchor bolt specified in the design, the qualified anchor bolts are processed and the anchor bolts are placed in the center of the hole through the anchor bolt calibration structure.

[0025] 4. Grouting: Insert the grouting plastic pipe that meets the hole depth requirements into the hole, about 0.5 to 1.0m from the bottom of the hole, and then inject pure cement slurry with a water-cement ratio of 0.45 to 0.5 into the hole. The grouting pressure should not be less than 0.4MPa to ensure that the space between the anchor rod and the hole wall is filled with cement slurry; the grouting should be gradually withdrawn from the inside to the outside, and the hole mouth can be blocked and sealed when there is a slight overflow phenomenon;

[0026] 5. Hanging the mesh: On the repaired slope surface, lay a layer of steel mesh according to the design requirements of each slope surface. Use wire ties to tie the mesh bars at intervals. The steel bars must be firmly overlapped. Ensure that there is a protective layer when hanging the mesh;

[0027] 6. Reinforcement welding: After the anchor grouting and mesh binding construction are completed, use ribbed steel bars to connect the anchor heads and weld them to the rod body. Each welding point must be firm.

[0028] 7. Sprayed concrete: After the above steps are completed, the concrete can be sprayed; the concrete strength is C20 fine stone concrete, and the thickness is 100mm; the surface of the sprayed concrete is required to be basically flat.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] In the foundation pit protection in the steel shield protection construction, the present invention provides an anchor rod calibration structure, so that the anchor rod can be calibrated and installed in the center of the grouting hole when the anchor rod is laid, thereby ensuring the quality of the anchor rod construction and further ensuring the quality of the pit protection. Furthermore, the support assembly provided can be used in conjunction with the anchor rod calibration structure to strengthen the construction stability of the anchor rod, which has a positive effect on the foundation pit protection in the overall steel shield protection construction; and the design of a suitable construction method reduces the interference to the highway during the construction process and can better meet the actual construction needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the connection of the steel shield foundation pit protection structure of the present invention;

[0032] Figure 2 This is a schematic diagram of the connection between the anchor rod and the anchor rod calibration structure of the present invention;

[0033] Figure 3 This is a schematic diagram of the connection of the anchor rod calibration structure of the present invention;

[0034] Figure 4 This is a schematic diagram of the connection of the calibration thread column structure in the anchor calibration structure of the present invention;

[0035] Figure 5 This is a top view of the internal structure connection of the carrier ring of the present invention;

[0036] Figure 6 This is a bottom view of the internal structure connection of the carrier ring of the present invention;

[0037] Figure 7 For the present invention Figure 6 A magnified schematic diagram of the local structural connection;

[0038] Figure 8 This is a schematic diagram of the structural connection of the support assembly of the present invention.

[0039] In the figure: foundation pit slope 1, steel mesh 2, grouting hole 3, anchor rod 4, load-bearing ring 501, fixing tube 502, calibration threaded column 503, rotating screw head 504, connecting threaded cone 505, accommodating cover 506, limiting inner ring 507, auxiliary ball 508, internal thread driving ring 509, auxiliary handle 510, arc-shaped auxiliary inclined groove 511, annular accommodating cavity 512, transmission bar 513, support block 514, connecting spring 515, connecting threaded groove body 516, connecting foot plate 601, mounting hole 602, support rod body 603, round hole 604, fastening anchor nail 605, cover cap 606. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are described clearly and completely below. The embodiments of the present invention and all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0041] Example 1: Please refer to Figure 1-Figure 7 A steel shield protection mechanism includes a steel mesh 2, grouting holes 3, anchor rods 4, and an anchor rod calibration structure; the steel mesh 2 is laid on a foundation pit slope 1, grouting holes 3 are evenly spaced on the foundation pit slope 1, anchor rods 4 are arranged in the grouting holes 3, and the anchor rods 4 are calibrated by the anchor rod calibration structure;

[0042] Foundation pit construction:

[0043] 1. Determine the slope top excavation line and the size of the working foundation pit based on the on-site soil quality and the designed bottom elevation and plane dimensions of the box body. The working pit is located on the east side of the highway, with a size of 43.5*66m, and uses two-level slope excavation.

[0044] Second, the side slopes near the highway must be manually brushed to ensure the stability and compactness of the roadbed slope soil. The excavation of the other three side slopes must also ensure that the plane is complete, with no vertical bumps or irregularities such as arcs in the horizontal direction.

[0045] 3. Steel bars and shotcrete are hung on the slope of the working pit. The concrete grade is C20. Drainage ditches are set up around the working pit to guide the water flow into the collection pit and pump it out in time. Intercepting ditches are set up around the top of the working pit to intercept rainwater from flowing into the working pit.

[0046] 4. After the foundation pit is excavated, the construction of the slide plate and back seat should be carried out as soon as possible to make the foundation pit completely closed and avoid being soaked by rainwater;

[0047] Hanging mesh sprayed concrete slope protection construction

[0048] The mesh spraying support should be closely coordinated with the foundation pit excavation, and each process should be carried out in parallel and in an orderly manner;

[0049] 1. Construction sequence of anchor and shotcrete support: slope repair → line setting → drilling → anchor rod installation → grouting → steel mesh hanging → reinforcement welding → shotcrete spraying;

[0050] 2. Drilling anchor holes: Use a drilling rig to drill holes. Measure and draw lines at 1.5m×1.5m intervals according to the designed hole positions. Mark the exact hole positions. Then drill holes according to the designed hole length, hole depression angle, and hole diameter. Pay strict attention to quality and record the acceptance of each hole. Unqualified holes will be deemed as waste holes and must be re-drilled. The anchor holes are arranged in a plum blossom shape, and the depression angle can be adjusted according to actual conditions.

[0051] 3. Anchor bolt installation: according to the length and diameter of the anchor bolt specified in the design, the qualified anchor bolts are processed and the anchor bolts are placed in the center of the hole through the anchor bolt calibration structure.

[0052] 4. Grouting: Insert the grouting plastic pipe that meets the hole depth requirements into the hole, about 0.5 to 1.0m from the bottom of the hole, and then inject pure cement slurry with a water-cement ratio of 0.45 to 0.5 into the hole. The grouting pressure should not be less than 0.4MPa to ensure that the space between the anchor rod and the hole wall is filled with cement slurry; the grouting should be gradually withdrawn from the inside to the outside, and the hole mouth can be blocked and sealed when there is a slight overflow phenomenon;

[0053] 5. Hanging the mesh: On the repaired slope surface, lay a layer of steel mesh according to the design requirements of each slope surface. Use wire ties to tie the mesh bars at intervals. The steel bars must be firmly overlapped. Ensure that there is a protective layer when hanging the mesh;

[0054] 6. Reinforcement welding: After the anchor grouting and mesh binding construction are completed, use ribbed steel bars to connect the anchor heads and weld them to the rod body. Each welding point must be firm.

[0055] 7. Sprayed concrete: After the above steps are completed, sprayed concrete can be applied. The concrete strength is C20 fine stone concrete with a thickness of 100mm. The surface of the sprayed concrete must be basically flat.

[0056] Example 2: Based on Example 1, please refer to Figure 2-Figure 7The anchor calibration structure here includes a load ring 501, a fixed cylinder 502, a calibration threaded column 503, a rotating screw head 504, a connecting threaded cone 505, a receiving cover 506, a limiting inner ring 507, an auxiliary ball 508, an internal threaded driving ring 509, an auxiliary handle 510, an arc-shaped auxiliary inclined groove 511, an annular receiving cavity 512, a transmission bar 513, a support block 514, a connecting spring 515, and a connecting threaded groove body 516; the load ring 501 is fixedly provided with a fixed cylinder 502, and the fixed cylinder 502 is equidistantly threadedly connected with a calibration threaded column 50 3. A rotating screw head 504 is fixedly provided at one end of the calibration threaded column 503, and a connecting threaded platform 505 is fixedly provided at the other end of the calibration threaded column 503. The connecting threaded platform 505 is threadedly connected to the receiving cover 506. A limited inner ring 507 is fixedly provided at one end of the receiving cover 506, and an auxiliary ball 508 is placed in the receiving cover 506. An annular receiving cavity 512 is provided in the carrying ring 501, and an internal threaded driving ring 509 is threadedly provided in the annular receiving cavity 512. An auxiliary handle 509 is symmetrically fixed on the internal threaded driving ring 509. 10, and the bottom end of the internal thread drive ring 509 is equidistantly provided with an arc-shaped auxiliary inclined groove 511, a transmission bar 513 is equidistantly movably provided in the carrying ring 501, one end of the transmission bar 513 extends into the arc-shaped auxiliary inclined groove 511, and a support block 514 is fixedly provided at the other end of the transmission bar 513, and the support block 514 is equidistantly movably provided in the placement groove, and the placement groove is provided in the carrying ring 501, and a connecting spring 515 is fixedly provided at one end of the support block 514 connected to the transmission bar 513, and the other end of the connecting spring 515 is fixedly provided in the placement groove, and the support block A connecting threaded groove body 516 is provided on 514; the calibration threaded column 503 here is evenly spaced and arranged in three groups on the fixed cylinder 502; the internal threaded drive ring 509 here is arranged in the same number of groups as the carrying ring 501; the support block 514 here is arranged in a corresponding position to the transmission bar 513 and is arranged in the same number of groups; the transmission bar 513 is arranged in a corresponding position to the arc-shaped auxiliary bevel groove 511 and is arranged in the same number of groups; the thickness of the transmission bar 513 here is less than the depth of the arc-shaped auxiliary bevel groove 511, and the end of the transmission bar 513 extending to the arc-shaped auxiliary bevel groove 511 is arranged as an arc surface.

[0057] When installing the anchor rod 4 in this embodiment, first place the supporting ring 501 at the orifice position of the grouting hole 3, then drive the transmission bar 513 by rotating the internal thread driving ring 509, and the transmission bar 513 pushes the support block 514 until the support block 514 squeezes the inner wall of the grouting hole 3, and then insert the anchor rod 4 from the fixed tube 502. At this time, rotate the calibration thread column 503 again so that the auxiliary ball 508 provided at the end of the calibration thread column 503 contacts the side wall of the anchor rod 4, so that the anchor rod 4 is in the center position of the grouting hole 3, and then continue to push the anchor rod 4 until the anchor rod 4 is positioned.

[0058] At this time, the anchor rod calibration structure can be disassembled for turnover use; that is, rotate the internal thread drive ring 509 in the opposite direction, contact the support block 514 to squeeze the side wall of the grouting hole 3, and directly remove the bearing ring 501.

[0059] Example 3: Based on Example 2, please refer to Figure 8 When auxiliary support is required for the anchor rod 4, support is provided by a support assembly, which includes a connecting foot plate 601, a mounting hole 602, a support rod body 603, a circular hole 604, a fastening anchor 605, and a cap 606; one end of the support rod body 603 is fixedly provided with a connecting foot plate 601, and the other end of the support rod body 603 is fixedly provided with a flat plate, a mounting hole 602 is provided on the connecting foot plate 601, and the connecting foot plate 601 is fixedly connected to the support block 514 by screws, a circular hole 604 is provided on the flat plate, and a cap 606 is fixedly provided on one end of the fastening anchor 605; the support rod body 603 here corresponds to the support block 514 in the setting position and has the same number of settings.

[0060] The support assembly designed in this embodiment is intended to be used in conjunction with the anchor rod calibration structure, that is, if the anchor rod calibration structure does not need to be disassembled, the anchor rod 4 can be further stabilized and strengthened by cooperating with the support assembly and the anchor rod calibration structure. At this time, the connecting foot plate 601 at one end of the support rod body 603 is fixedly connected to the support block 514, and the flat plate at the other end of the support rod body 603 is inserted into the foundation pit slope 1 for positioning by fastening the anchor nail 605.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A steel shield protection mechanism, characterized by: The invention comprises a steel mesh (2), grouting holes (3), anchor rods (4) and an anchor rod calibration structure; the steel mesh (2) is laid on a foundation pit slope (1); grouting holes (3) are arranged at equal intervals on the foundation pit slope (1); anchor rods (4) are arranged in the grouting holes (3); and the anchor rods (4) are calibrated by the anchor rod calibration structure.

2. A steel shield protection mechanism according to claim 1, characterized in that: The anchor rod calibration structure comprises a bearing ring (501), a fixing tube (502), a calibration threaded column (503), a rotating screw head (504), a connecting threaded cone (505), a receiving cover (506), a limiting inner ring (507), an auxiliary ball (508), an internal threaded driving ring (509), an auxiliary handle (510), an arc-shaped auxiliary inclined groove (511), an annular receiving cavity (512), a transmission bar (513), a support block (514), a connecting spring (515), and a connecting threaded groove body (516); A fixing cylinder (502) is fixedly provided on the carrying ring (501), and a calibration thread column (503) is fixedly provided on the fixing cylinder (502) in an equidistant thread connection, a rotating screw head (504) is fixedly provided on one end of the calibration thread column (503), and a connecting threaded cone (505) is fixedly provided on the other end of the calibration thread column (503), and the connecting threaded cone (505) is threadedly connected to the accommodating cover (506), and a limiting inner ring (507) is fixedly provided on one end of the accommodating cover (506), and the accommodating cover (506) is fixedly provided with a limiting inner ring (507). An auxiliary ball (508) is placed in the bearing ring (506), an annular accommodating cavity (512) is provided in the bearing ring (501), an internal thread driving ring (509) is provided in the annular accommodating cavity (512) in a threaded connection, an auxiliary handle (510) is symmetrically fixed on the internal thread driving ring (509), and an arc-shaped auxiliary inclined groove (511) is equidistantly provided at the bottom end of the internal thread driving ring (509), the transmission bar (513) is equidistantly provided in the bearing ring (501), and the transmission bar (513) is equidistantly provided in the bearing ring (501). ) extends into the arc-shaped auxiliary inclined groove (511), the other end of the transmission bar (513) is fixedly provided with a support block (514), the support block (514) is equidistantly movably provided in the placement groove, and the placement groove is provided in the carrying ring (501), the support block (514) is fixedly provided with a connecting spring (515) at one end connected to the transmission bar (513), the other end of the connecting spring (515) is fixedly provided in the placement groove, and the support block (514) is provided with a connecting thread groove body (516).

3. A steel shield protection mechanism according to claim 2, characterized in that: The calibration threaded columns (503) are arranged in three groups at equal intervals on the fixed cylinder (502).

4. A steel shield protection mechanism according to claim 2, characterized in that: The number of sets of the internal thread drive ring (509) and the carrying ring (501) is the same.

5. The steel shield protection mechanism according to claim 2, characterized in that: The support blocks (514) and the transmission bars (513) are arranged at corresponding positions and are provided in the same number of groups; the transmission bars (513) and the arc-shaped auxiliary inclined grooves (511) are arranged at corresponding positions and are provided in the same number of groups.

6. A steel shield protection mechanism according to claim 2, characterized in that: The thickness of the transmission bar (513) is smaller than the depth of the arc-shaped auxiliary inclined groove (511), and the end of the transmission bar (513) extending to the arc-shaped auxiliary inclined groove (511) is configured as an arc-shaped surface.

7. The steel shield protection mechanism according to claim 1, characterized in that: When auxiliary support is required for the anchor rod (4), support is provided by a support assembly, which includes a connecting foot plate (601), a mounting hole (602), a support rod body (603), a circular hole (604), a fastening anchor nail (605), and a cap (606); one end of the support rod body (603) is fixedly provided with a connecting foot plate (601), and the other end of the support rod body (603) is fixedly provided with a flat plate, the connecting foot plate (601) is provided with a mounting hole (602), and the connecting foot plate (601) is fixedly connected to the support block (514) by screws, the flat plate is provided with a circular hole (604), and one end of the fastening anchor nail (605) is fixedly provided with a cap (606).

8. The steel shield protection mechanism according to claim 7, characterized in that: The support rods (603) and the support blocks (514) are arranged at corresponding positions and have the same number of groups.

9. A shallow soil-covered underpass roadbed construction method, comprising a steel shield protection mechanism according to any one of claims 1 to 8, characterized in that: Foundation pit construction:

1. Determine the slope top excavation line and the size of the working foundation pit based on the on-site soil quality and the designed bottom elevation and plane dimensions of the box body. The working pit is located on the east side of the highway, with a size of 43.5*66m, and uses two-level slope excavation. Second, the side slopes near the highway must be manually brushed to ensure the stability and compactness of the roadbed slope soil. The excavation of the other three side slopes must also ensure that the plane is complete, with no vertical bumps or irregularities such as arcs in the horizontal direction.

3. Steel bars and shotcrete are hung on the slope of the working pit. The concrete grade is C20. Drainage ditches are set up around the working pit to guide the water flow into the collection pit and pump it out in time. Intercepting ditches are set up around the top of the working pit to intercept rainwater from flowing into the working pit.

4. After the foundation pit is excavated, the construction of the slide plate and back seat should be carried out as soon as possible to make the foundation pit completely closed and avoid being soaked by rainwater; Hanging mesh sprayed concrete slope protection construction The mesh spraying support should be closely coordinated with the foundation pit excavation, and each process should be carried out in parallel and in an orderly manner; 1. Construction sequence of anchor and shotcrete support: slope repair → line setting → drilling → anchor rod installation → grouting → steel mesh hanging → reinforcement welding → shotcrete spraying; 2. Drilling anchor holes: Use a drilling rig to drill holes. Measure and draw lines at 1.5m×1.5m intervals according to the designed hole positions. Mark the exact hole positions. Then drill holes according to the designed hole length, hole depression angle, and hole diameter. Pay strict attention to quality and record the acceptance of each hole. Unqualified holes will be deemed as waste holes and must be re-drilled. The anchor holes are arranged in a plum blossom shape, and the depression angle can be adjusted according to actual conditions.

3. Anchor rod installation: according to the length and diameter of the anchor rod specified in the design, the qualified anchor rod is processed, and the anchor rod (4) is placed in the center of the hole through the anchor rod calibration structure; 4. Grouting: Insert the grouting plastic pipe that meets the hole depth requirements into the hole, about 0.5 to 1.0m from the bottom of the hole, and then inject pure cement slurry with a water-cement ratio of 0.45 to 0.5 into the hole. The grouting pressure should not be less than 0.4MPa to ensure that the space between the anchor rod and the hole wall is filled with cement slurry; the grouting should be gradually withdrawn from the inside to the outside, and the hole mouth can be blocked and sealed when there is a slight overflow phenomenon; 5. Hanging the mesh: On the slope surface that has been repaired, lay a layer of steel mesh (2) according to the design requirements of each slope surface. Tie the mesh bars with wire at intervals. The steel bars must be firmly overlapped. Ensure that there is a protective layer when hanging the mesh; 6. Reinforcement welding: After the anchor grouting and mesh binding construction are completed, use ribbed steel bars to connect the anchor heads and weld them to the rod body. Each welding point must be firm.

7. Spraying concrete: After the above process is completed, spraying concrete can be carried out; the concrete strength is C20 fine stone concrete, and the thickness is 100mm; The surface of shotcrete is required to be basically flat.

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