Method for removing and reinforcing and repairing lattice column pile under bottom plate of open-cut tunnel

Abstract

The application discloses a method for removing, reinforcing and repairing lattice column piles under a bottom plate of an open-cut tunnel, and steps are as follows: first, positioning the lattice column piles to be removed at the bottom plate of the tunnel; then, setting a temporary reinforcing structure and multiple MJS grouting holes which are uniformly distributed around the lattice column piles at the bottom plate, MJS jet grouting is performed on the soil under the bottom plate to reinforce the soil, a pile pulling hole is set at the bottom plate, and a guide device is arranged around the pile pulling hole; multiple sleeves which are connected in a head-to-tail mode are buried in the pipe structure in a tunneling mode along the lattice column piles downward from the pile pulling hole; the lattice column piles are lifted out from the pipe structure, cut into multiple pieces in the tunnel and then transported out; after the lattice column piles are removed, a pouring and vibrating pipe is inserted into the pile pulling hole, C15 concrete is poured while the pipe structure is pulled out, and the sleeves are removed one by one; finally, the bottom plate is repaired. The application can reduce the influence of pile pulling construction on the tunnel structure, reduce the risk of the bottom plate, and improve the pile pulling efficiency.

Description

Technical Field

[0001] This invention relates to the field of pile foundation removal technology, and in particular to a method for removing, reinforcing and repairing lattice column piles under the bottom slab of an open-cut tunnel. Background Technology

[0002] Currently, with the development of urban underground space, cases of mutual influence between different projects are common, often requiring the removal of existing pile foundations to meet the needs of later construction. Literature review reveals numerous cases of pile foundation removal under buildings, bridges, revetments, and other structures. Cases of removing pile foundations under the structural slab within tunnels are relatively rare.

[0003] When lattice piles are not used as engineering piles, they are usually designed as temporary components for foundation pit support. Theoretically, removing lattice piles should not have a long-term stress impact on the existing tunnel structure when there are inter-project interferences. However, the vibration of large pile extraction equipment during the removal process can adversely affect the tunnel structure. If reasonable pile extraction methods are not adopted and temporary structural reinforcement and effective repair are not carried out, the tunnel will suffer permanent damage, such as uneven settlement, cracks, and water leakage.

[0004] There are four main methods for removing pile foundations: The first method is to break the bottom slab inside the tunnel, lift it directly, and cut it off in sections; the second method is to use a high-pressure water jet to eliminate the side friction between the pile foundation and the soil and rock, and then pull it out directly; the third method is to use a full-rotation drilling rig to impact the pile body with the sleeve until it breaks and grab out the broken parts; the fourth method is to follow the full-rotation sleeve to the bottom of the pile foundation, hold the pile foundation tightly, and then lift and pull it out.

[0005] The following drawbacks exist in practical applications: 1. The method of directly removing the pile foundation slab inside the tunnel is difficult due to the large skin friction of the piles. The equipment occupies a large area, making it difficult to operate inside the tunnel, and pile breakage is likely to occur. In soft, water-rich soil areas, there is a high risk of water seepage from the foundation slab, and the holes are prone to collapse after pile removal, which is detrimental to the structure.

[0006] 2. When removing equipment from the ground, a double-sleeve method is typically used, placing most of the equipment on the ground. This not only affects normal operations inside the tunnel but also disrupts surface traffic. This method requires breaking through the roof slab, which is difficult to repair and prone to subsequent water leakage.

[0007] 3. When high-pressure water jets are used for assisted removal instead of full sleeves, the soil at the bottom of the tunnel will be directly disturbed. In soft soil conditions, the impact will be more extensive and last for a longer period, which can easily cause uneven settlement of the bottom slab.

[0008] 4. Using a full-rotation drilling rig to impact the pile body with a sleeve until it breaks and removes the debris, impact drilling significantly disturbs the tunnel structure. Sleeve removal does not remove the entire pile, and in soft soil conditions, it can easily cause the pile foundation to be washed into deeper layers, making complete removal impossible. Due to the large space occupied by the equipment, this method should ideally be carried out on the ground using a double-sleeve system, which will also affect the ground environment. Furthermore, this method is prone to leaving residual reinforcing steel.

[0009] 5. Using a full-rotation sleeve to follow the pile to the bottom and pull the pile tightly occupies a large space and is not suitable for the construction conditions of pile extraction in tunnels.

[0010] Traditional pile extraction methods fail to consider the low clearance conditions within existing tunnels, nor the adverse effects of pile extraction on the structure. In soft, water-rich soil areas, breaking through the floor slab can easily lead to water seepage, and without intervention, borehole collapse is likely after pile extraction, negatively impacting the structural integrity. The double-sleeve pile extraction method performed on the surface increases the risk of roof leakage, reduces extraction efficiency, and also affects the surface environment.

[0011] Therefore, how to reduce the impact of pile extraction on the structure, minimize the impact on the ground environment while ensuring operational safety, and improve pile extraction efficiency has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0012] In view of the above-mentioned deficiencies of the prior art, the present invention provides a method for removing, reinforcing and repairing the lattice column piles under the bottom slab of an open-cut tunnel, the purpose of which is to reduce the impact of pile extraction on the structure and improve the efficiency of pile extraction.

[0013] To achieve the above objectives, this invention discloses a method for removing, reinforcing, and repairing lattice column piles under the floor slab of an open-cut tunnel, comprising the following steps:

[0014] Step 1: Stop the operation of the tunnel and locate the position of the lattice column piles to be removed below the bottom slab of the tunnel;

[0015] Step 2: Set multiple MJS grouting holes evenly distributed around the axis of the lattice column pile on the base plate, and use multiple MJS grouting holes to reinforce the soil around the lattice column pile below the base plate with MJS grouting to form a reinforced body;

[0016] Step 3: Temporary reinforcement structures are provided between the side wall of the tunnel near the lattice column pile and the bottom slab and / or between the partition wall and the bottom slab;

[0017] Step 4: Chisel open the base plate to form a pile extraction hole with a diameter at least 600 mm larger than the outer diameter of the lattice column pile.

[0018] Step 5: On the base plate, a guide device is set around the pile extraction hole, and the first sleeve is hoisted; after the first sleeve is in place, the first sleeve is connected to the power device.

[0019] Step 6: Start the power unit and excavate the first section of the sleeve downward along the outer wall of the lattice column pile. At the same time, inject cement slurry to replace the mud generated during excavation and keep the liquid level of the cement slurry at a position 500 mm below the upper surface of the bottom plate.

[0020] Step 7: When the uppermost sleeve of all the sleeves driven by the power unit is about to be submerged in the pile extraction hole, stop the power unit, disconnect the power unit from the corresponding sleeve, connect the next sleeve section to the sleeve that is about to be submerged in the pile extraction hole, reconnect the next sleeve section to the power unit, and then continue to excavate downwards.

[0021] Step 8: Repeat step 7 until the lower end of the tubular structure formed by the multiple sequentially connected sleeves exceeds the bottom of the lattice column pile, then stop the downward excavation;

[0022] Step 9: Drive the tube structure to rotate in both forward and reverse cycles using the power device until frictional resistance is eliminated;

[0023] Step 10: Remove the power unit and the guide device, and install the hanger;

[0024] Step 11: Install lifting equipment on the gantry to lift the lattice column pile; simultaneously perform mud backfilling during the lifting process; when the upper end of the lattice column pile is lifted to a position close to the top slab of the tunnel, use pipe clamps to hold the lattice column pile near the bottom slab of the tunnel, constraining the lattice column pile from sliding downwards along the extraction hole; then use a wire saw to cut off the portion of the lattice column pile above the pipe clamps and send it out of the tunnel;

[0025] Step 12: Repeat step 11 until the lattice column piles are completely sent out of the tunnel;

[0026] Step 13: Insert the tamping pipe into the bottom of the pipe structure through the pile extraction hole, pour C15 concrete while pulling out the pipe structure, and remove the sleeves one by one until all the sleeves are removed.

[0027] Step 14: Repair the location where the base plate was chiseled open, remove the temporary reinforcement structure, and restore the tunnel's crash barrier and pavement layer.

[0028] Preferably, in step 2, eight MJS grouting holes are evenly distributed around the axis of the lattice column pile on the base plate;

[0029] The diameter of each of the MJS grouting holes is between 1100 mm and 1400 mm;

[0030] In the multiple reinforced bodies formed by MJS shotcrete reinforcement, the overlap between any two reinforced bodies is not less than 500 mm.

[0031] Preferably, in step 2, when performing MJS shotcrete reinforcement, if there is a confined water layer within the range of the lattice column pile, the confined water should be isolated; if there is no confined water within the range of the lattice column pile, the depth of the reinforcement body should be determined according to the law of groundwater infiltration.

[0032] The bottom of each of the aforementioned solidified bodies is at least 5 meters away from the bottom of the tunnel.

[0033] Preferably, in step 3, each of the temporary reinforcing structures is a triangular reinforcing armpit plate;

[0034] Each of the aforementioned reinforcing haunches is at least 400 mm thick and is disposed between the corresponding side wall and the bottom plate and / or between the corresponding partition wall and the bottom plate. The haunches are connected to the corresponding side wall, the corresponding bottom plate or the corresponding partition wall by rebar anchoring.

[0035] Preferably, in step 10, the hanger is a support system comprising multiple sets of strokes.

[0036] Preferably, in step 14, the process of repairing the location where the base plate has been chiseled open is as follows:

[0037] According to the dimensions of the location where the base plate was chiseled open, tie the repair and reinforcement steel bars, and weld the repair and reinforcement steel bars to the original steel bars of the base plate;

[0038] A penetrating crystalline coating is sprayed onto the original concrete surface of the base plate, and two layers of water-swellable rubber strips are attached.

[0039] After pre-embedding the grouting pipes, micro-expansion steel fiber reinforced concrete is poured to complete the structural repair of the base plate;

[0040] Once the micro-expansion steel fiber concrete reaches 100% strength, grouting is performed on the area above the bottom surface of the base plate through the pre-embedded grouting pipe.

[0041] After grouting is completed, the pre-embedded grouting pipe is sealed;

[0042] Two layers of waterproof membrane are adhered to the upper surface of the base plate.

[0043] More preferably, the lap weld length between the repair and reinforcement steel bars and the original steel bars of the base plate is not less than 200 mm.

[0044] More preferably, one layer of penetrating reactive waterproof membrane and one layer of conventional waterproof membrane are adhered to the upper surface of the base plate, with the membrane coverage extending 300 mm beyond the outer edge of the base plate repair area.

[0045] The beneficial effects of this invention are:

[0046] The application of this invention can reduce the impact of pile extraction on the structure and improve pile extraction efficiency.

[0047] This invention can effectively provide temporary reinforcement to the tunnel structure and reduce the damage to the structure caused by sheet piles.

[0048] This invention employs MJS shotcrete reinforcement to seal the area below the tunnel floor, isolating confined water and reducing its impact on pile extraction operations. The invention also utilizes a pipe structure formed by multiple sleeves to prevent borehole wall collapse and employs mud replacement for soil removal, reducing the risk of groundwater inrush and making the process safer and more reliable.

[0049] This invention solves the problem of seepage prevention in the foundation slab by using hole sealing and multiple water-stopping methods.

[0050] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0051] Figure 1 This diagram shows a cross-sectional view of the completed pile extraction hole opening in one embodiment of the present invention.

[0052] Figure 2 This is a schematic diagram of the planar state after the pile extraction hole is opened in one embodiment of the present invention.

[0053] Figure 3 This diagram shows a cross-sectional view of the first sleeve section after it has been installed in one embodiment of the present invention.

[0054] Figure 4 This diagram shows a cross-sectional view of the completed downward excavation of all sleeves in one embodiment of the present invention.

[0055] Figure 5 This diagram shows a cross-sectional view of the hanger setup in one embodiment of the present invention.

[0056] Figure 6 This diagram shows a cross-sectional view of a lattice column pile being lifted out and divided in one embodiment of the present invention.

[0057] Figure 7 This diagram shows a partially enlarged view of a pipe clamp securing a lattice column pile to prevent it from moving downwards along the pile extraction hole, according to an embodiment of the present invention.

[0058] Figure 8 This diagram shows a cross-sectional view of a pipe structure formed by a sleeve being lifted out and the sleeve being removed, according to an embodiment of the present invention.

[0059] Figure 9 This diagram shows a cross-sectional view of the repair of a section of the tunnel floor slab that has been removed, according to an embodiment of the present invention. Detailed Implementation

[0060] Example: Figures 1 to 9 As shown, the method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel includes the following steps:

[0061] Step 1: Stop the operation of Tunnel 1 and locate the position of the lattice column pile 2 to be removed below the bottom slab of Tunnel 1;

[0062] Step 2: Set multiple MJS grouting holes 3 evenly distributed around the axis of the lattice column pile 2 on the base plate, and use multiple MJS grouting holes 3 to reinforce the soil around the lattice column pile 2 below the base plate with MJS grouting to form a reinforced body 4.

[0063] Step 3: Temporary reinforcing structures 5 are installed between the side wall and the bottom slab of tunnel 1 near the lattice column pile 2 and / or between the partition wall and the bottom slab;

[0064] Step 4: Chisel open the bottom plate to form a pile extraction hole 6 with a diameter greater than 600 mm of the outer diameter of the lattice column pile 2.

[0065] In practical applications, the diameter of the pile extraction hole 6 is more than 600 mm larger than the outer diameter of the lattice column pile 2, which facilitates the pressing of the sleeve 9 in subsequent steps and provides space for operations such as welding steel bars.

[0066] Step 5: On the base plate, a guide device 7 is set around the pile extraction hole 6, and the first sleeve 9 is hoisted; after the first sleeve 9 is in place, the first sleeve 9 is connected to the power device 8.

[0067] Step 6: Start the power unit 8 and excavate the first sleeve 9 downward along the outer wall of the lattice column pile 2. At the same time, inject cement grout to replace the mud generated during excavation and keep the liquid level of the cement grout at a position 500 mm below the upper surface of the bottom plate.

[0068] Step 7: When the tunneling reaches the point where the uppermost sleeve 9 driven by the power unit 8 is about to be submerged in the pile extraction hole 6, stop the power unit 8, disconnect the power unit 8 from the corresponding sleeve 9, connect the next sleeve 9 to the sleeve 9 that is about to be submerged in the pile extraction hole 6, and reconnect the next sleeve 9 to the power unit 8, and then tunnel downwards again.

[0069] Step 8: Repeat step 7 until the lower end of the pipe structure formed by multiple sequentially connected sleeves 9 exceeds the bottom of the lattice column pile 2, then stop the downward excavation;

[0070] Step 9: Drive the tube structure to rotate in both forward and reverse cycles through the power unit 8 until the frictional resistance is eliminated;

[0071] Step 10: Remove the power unit 8 and the guide device 7, and install the hanger 10;

[0072] Step 11: Set up lifting equipment on the gantry 10 to lift the lattice column pile 2; simultaneously perform mud backfilling during the lifting of the lattice column pile 2; when the upper end of the lattice column pile 2 is lifted to a position close to the top slab of the tunnel 1, use pipe clamps 11 to hold the lattice column pile 2 near the bottom slab of the tunnel 1 to prevent the lattice column pile 2 from sliding down along the extraction hole 6; then use a wire saw 12 to cut off the part of the lattice column pile 2 above the pipe clamps 11 and send it out of the tunnel 1;

[0073] Step 12: Repeat step 11 until the lattice column pile 2 is completely sent out of tunnel 1;

[0074] Step 13: Insert the tamping pipe into the pile extraction hole 6 to the bottom of the pipe structure, pour C15 concrete while pulling out the pipe structure, and remove the sleeves 9 one by one until all sleeves 9 are removed.

[0075] Step 14: Repair the area where the bottom plate was chiseled open, remove the temporary reinforcement structure 5, and restore the crash barrier and pavement layer of Tunnel 1.

[0076] In some embodiments, in step 2, eight MJS grouting holes 3 are evenly distributed around the axis of the lattice column pile 2 on the base plate;

[0077] The diameter of each MJS grouting hole 3 is 1100 mm to 1400 mm;

[0078] In the multiple reinforced bodies 4 formed by MJS shotcrete reinforcement, the overlap between any two reinforced bodies 4 is not less than 500 mm.

[0079] In practical applications, the depth of the multiple reinforced bodies 4 formed by MJS shotcrete reinforcement depends on the geological conditions.

[0080] In some embodiments, during step 2, when performing MJS shotcrete reinforcement, if there is a confined water layer within the range of the lattice column pile 2, the confined water should be isolated; if there is no confined water within the range of the lattice column pile 2, the depth of the corresponding reinforcement body 4 should be determined according to the law of groundwater seepage.

[0081] The bottom of each solidified body 4 is at least 5 meters away from the bottom of tunnel 1.

[0082] In some embodiments, in step 3, each temporary reinforcing structure 5 is a triangular reinforcing armpit plate;

[0083] Each reinforcing haunch plate is at least 400 mm thick and is installed between the corresponding side wall and the bottom plate and / or between the corresponding partition wall and the bottom plate. It is connected to the corresponding side wall, the corresponding bottom plate or the corresponding partition wall by rebar anchoring.

[0084] In practical applications, if tunnel 1 includes a partition wall that divides the internal space into two horizontally arranged passages, then two sets of eight reinforcing haunches are respectively installed between the two side walls and the bottom slab of tunnel 1, and between the two sides of the partition wall and the bottom slab, located at the entrance and exit positions of the lattice column piles 2 respectively.

[0085] In some embodiments, in step 10, the hanger 10 is a support system including multiple sets of strokes.

[0086] In some embodiments, the process of repairing the location where the base plate was chiseled open in step 14 is as follows:

[0087] According to the dimensions of the location where the base plate was chiseled open, tie the repair and reinforcement steel bars 14, and weld the repair and reinforcement steel bars 14 to the original steel bars of the base plate;

[0088] Spray a penetrating crystalline coating onto the existing concrete surface of the base plate and attach two layers of water-swellable rubber strips 15;

[0089] After pre-embedding the grouting pipes, micro-expansion steel fiber reinforced concrete was poured to complete the structural repair of the base plate;

[0090] Once the micro-expansion steel fiber concrete reaches 100% strength, grouting is performed on the area above the bottom surface of the base slab through pre-embedded grouting pipes.

[0091] After grouting is completed, the pre-embedded grouting pipes are sealed.

[0092] Apply two layers of waterproof membrane to the upper surface of the base plate.

[0093] In some embodiments, the lap weld length of the repair and reinforcement steel bar 14 to the original steel bar of the base plate is not less than 200 mm.

[0094] In some embodiments, a layer of penetrating reactive waterproof membrane and a layer of conventional waterproof membrane are adhered to the upper surface of the base plate, with the adhesion area extending 300 mm beyond the outer edge of the base plate repair area.

[0095] In practical applications, the present invention constructs a triangular reinforcing armpit plate inside the tunnel 1 as a temporary reinforcing structure 5.

[0096] Before drilling into the bottom slab of Tunnel 1, MJS grouting holes 3 were arranged for all-round jet grouting to seal the groundwater under the bottom slab of Tunnel 1 and isolate the influence of confined water.

[0097] On the base plate, a pile extraction hole 6 is chiseled out, which is more than 600 mm larger in outer diameter than the outer diameter of the grid column pile 2;

[0098] Then, using machinery, multiple sleeves 9 are pressed into the soil section by section until they reach below the bottom of the lattice column pile 2.

[0099] During the pressing of sleeve 9, the front teeth are used to cut the soil and inject mud. The mud is used to replace the soil and carry it out while maintaining a certain liquid level.

[0100] Then, under the protection of sleeve 9, the lattice column pile 2 is pulled out and the mud level is maintained.

[0101] Remove sleeve 9 and inject C15 plain concrete.

[0102] Finally, the reinforcing steel bars for the removed portion of the base slab are installed and the sealing concrete is applied.

[0103] During the removal of the grid column pile 2, the mud system was used to maintain a certain safe level to prevent groundwater from gushing out.

[0104] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel; characterized in that, Includes the following steps: Step 1: Stop the operation of the tunnel (1) and locate the position of the lattice column pile (2) to be removed below the bottom plate of the tunnel (1); Step 2: Set multiple MJS grouting holes (3) evenly distributed around the axis of the lattice column pile (2) on the base plate, and use multiple MJS grouting holes (3) to reinforce the soil around the lattice column pile (2) below the base plate with MJS grouting to form a reinforced body (4). Step 3: Temporary reinforcing structures (5) are provided between the side wall of the tunnel (1) near the lattice column pile (2) and the bottom plate and / or between the partition wall and the bottom plate. Step 4: Chisel open the bottom plate to form a pile extraction hole (6) with a diameter greater than 600 mm of the outer diameter of the lattice column pile (2). Step 5: On the base plate, a guide device (7) is set around the pile extraction hole (6), and the first sleeve (9) is hoisted; after the first sleeve (9) is in place, the first sleeve (9) is connected to the power device (8); Step 6: Start the power device (8), excavate the first section of the sleeve (9) downward along the outer wall of the lattice column pile (2), and at the same time inject cement slurry to replace the mud generated during excavation, and keep the liquid level of the cement slurry at a position 500 mm below the upper surface of the bottom plate; Step 7: When the uppermost sleeve (9) of all the sleeves (9) driven by the power device (8) is about to be submerged in the pile extraction hole (6), pause the power device (8), disconnect the power device (8) from the corresponding sleeve (9), connect the next sleeve (9) to the sleeve (9) that is about to be submerged in the pile extraction hole (6), reconnect the next sleeve (9) to the power device (8), and then continue to excavate downwards. Step 8: Repeat step 7 until the lower end of the tube structure formed by the multiple sequentially connected sleeves (9) exceeds the bottom of the lattice column pile (2), then stop the downward excavation; Step 9: Drive the tube structure to rotate in both forward and reverse cycles through the power device (8) until the frictional resistance is eliminated; Step 10: Remove the power unit (8) and the guide device (7), and install the hanger (10). Step 11: Set up lifting equipment on the gantry (10) to lift the lattice column (2); while lifting the lattice column (2), simultaneously perform mud backfilling; when the upper end of the lattice column (2) is lifted to a position close to the top plate of the tunnel (1), use pipe clamps (11) to hold the lattice column (2) close to the bottom plate of the tunnel (1) to prevent the lattice column (2) from sliding down along the extraction hole (6); then use a wire saw (12) to cut off the part of the lattice column (2) above the pipe clamps (11) and send it out of the tunnel (1). Step 12: Repeat step 11 until the lattice column (2) is completely sent out of the tunnel (1). Step 13: Insert the tamping pipe into the pile extraction hole (6) to the bottom of the pipe structure, pour C15 concrete while pulling out the pipe structure, and remove the sleeves (9) one by one until all the sleeves (9) are removed. Step 14: Repair the location where the bottom plate was chiseled open, remove the temporary reinforcement structure (5), and restore the anti-collision wall and pavement layer of the tunnel (1).

2. The method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel according to claim 1, characterized in that, In step 2, eight MJS grouting holes (3) are evenly distributed around the axis of the lattice column pile (2) on the base plate. The diameter of each of the MJS grouting holes (3) is 1100 mm to 1400 mm; In the multiple reinforced bodies (4) formed by MJS shotcrete reinforcement, the overlap between any two reinforced bodies (4) is not less than 500 mm.

3. The method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel according to claim 1, characterized in that, In step 2, when performing MJS shotcrete reinforcement, if there is a confined water layer within the range of the lattice column pile (2), the confined water should be isolated; if there is no confined water within the range of the lattice column pile (2), the depth of the corresponding reinforced body (4) should be determined according to the law of groundwater infiltration. The bottom of each of the solidified bodies (4) is at least 5 meters away from the bottom of the tunnel (1).

4. The method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel according to claim 1, characterized in that, In step 3, each of the temporary reinforcing structures (5) is a triangular reinforcing armpit plate; Each of the aforementioned reinforcing haunches is at least 400 mm thick and is disposed between the corresponding side wall and the bottom plate and / or between the corresponding partition wall and the bottom plate. The haunches are connected to the corresponding side wall, the corresponding bottom plate or the corresponding partition wall by rebar anchoring.

5. The method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel according to claim 1, characterized in that, In step 10, the hanger (10) is a support system that includes multiple sets of strokes.

6. The method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel according to claim 1, characterized in that, In step 14, the process of repairing the area where the base plate was chiseled open is as follows: According to the dimensions of the location where the base plate was chiseled open, tie the repair and reinforcement steel bars (14) and weld the repair and reinforcement steel bars (14) to the original steel bars of the base plate; A penetrating crystalline coating is sprayed onto the original concrete surface of the base plate, and two layers of water-swellable rubber strips (15) are attached. After pre-embedding the grouting pipes, micro-expansion steel fiber reinforced concrete is poured to complete the structural repair of the base plate; Once the micro-expansion steel fiber concrete reaches 100% strength, grouting is performed on the area above the bottom surface of the base plate through the pre-embedded grouting pipe. After grouting is completed, the pre-embedded grouting pipe is sealed; Two layers of waterproof membrane (13) are pasted on the upper surface of the base plate.

7. The method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel according to claim 6, characterized in that, The lap weld length of the repair and reinforcement steel bar (14) and the original steel bar of the base plate shall not be less than 200 mm.

8. The method for removing, reinforcing, and repairing the lattice column piles under the bottom slab of an open-cut tunnel according to claim 6, characterized in that, One layer of penetrating reactive waterproof membrane and one layer of traditional waterproof membrane are pasted on the upper surface of the base plate, with the pasting area extending 300 mm beyond the outer edge of the base plate repair area.

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