Support changing method for underground corridor construction under deep foundation pit

Abstract

The invention relates to the field of civil engineering, and discloses a support changing method for underground corridor construction under a deep foundation pit, which comprises the following steps: S1, cantilever construction: adopting a steel pipe cantilever frame for supporting; s2, positioning is conducted, specifically, top elevation lines are positioned on the foundation pit supporting piles; s3, steel bar planting, wherein steel bars are planted in the support piles and anchored; s4, support changing plate mounting: mounting a support changing plate at the position of the support beam; s5, anti-seepage treatment is conducted, specifically, a groove is formed in the vertical face of the structure; s6, coiled material construction, wherein a waterproof coiled material is constructed on the basement outer wall; s7, backfilling a fertilizer groove, namely backfilling by using flow-state solidified soil; s8, removing the steel support: removing the steel support by using a truck crane; and S9, dismantling the concrete support: dismantling the concrete support by using a truck crane. The method is suitable for the large-space ultra-deep foundation pit which is large in depth and complex in geological condition, and the good effect can be achieved in different geological environments. Through reasonable construction measures, the stability and safety of the construction process can be guaranteed, and engineering accidents are effectively prevented.

Description

Technical Field

[0001] The invention relates to the field of civil engineering, and in particular to a method for replacing supports during construction of an underground corridor under a deep foundation pit. Background Art

[0002] In underground engineering construction, the excavation and support of deep foundation pits are extremely challenging, especially when the foundation pit is deep and needs to be connected with underground corridors. Generally, deep foundation pit projects face multiple difficulties such as complex geological conditions, the influence of groundwater, and the stability control of surrounding buildings. Therefore, the selection of construction methods and technologies plays a vital role in the safety and quality of the project.

[0003] In traditional deep foundation pit construction, the support system is usually not designed properly, or the support replacement process is not properly controlled, resulting in the ineffective guarantee of the stability of the foundation pit soil. In this case, the excavation process of the foundation pit will be accompanied by the release of a large amount of soil stress, especially in foundation pits with complex geological conditions or large depths, which is more likely to cause the foundation pit to become unstable or even collapse. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for replacing supports in the construction of an underground corridor under a deep foundation pit, which solves the problem that in traditional deep foundation pit construction, the support system design is unreasonable, which easily causes the instability or even collapse of the foundation pit.

[0005] To achieve the above purpose, the present invention is implemented by the following technical scheme: a method for replacing support during construction of an underground corridor under a deep foundation pit, comprising the following steps:

[0006] S1. Cantilever construction: Use steel pipe cantilever frame for support;

[0007] S2. Positioning: Position the top elevation line on the foundation pit support piles;

[0008] S3, planting reinforcement: planting reinforcement on the supporting piles and anchoring them;

[0009] S4, installation of replacement support plate: installation of replacement support plate at the support beam position;

[0010] S5. Anti-leakage treatment: grooves are set on the structural facade;

[0011] S6. Membrane construction: waterproof membrane is constructed on the basement exterior wall and additional layers are added at the support beam position;

[0012] S7, fertilizer tank backfill: After cleaning the garbage in the foundation pit, carry out waterproof protection layer construction and use fluidized solidified soil to backfill;

[0013] S8, Steel support removal: After the concrete reaches the required strength, use a truck crane to remove the steel support;

[0014] S9. Removal of concrete supports: After the steel supports are removed, use a truck crane to remove the concrete supports.

[0015] Preferably, in step S1, during cantilever construction, a steel pipe horizontal rod is used to be firmly connected to the top of the supporting pile, the top return horizontal rod is 200 to 400 mm away from the main node, and the horizontal and vertical spacings are both 3 to 4 meters.

[0016] Preferably, in step S2, the top elevation line is measured along a position parallel to the top plate of the structure for every other supporting pile on the foundation pit supporting piles.

[0017] Preferably, in the S3 step, after positioning, reinforcement planting is performed on each foundation pit supporting pile, and each reinforcement planting includes 10 to 15 steel bars with a diameter of 18 to 22 mm. One end of the steel bar is anchored 250 to 350 mm into the pile and anchored with reinforcement glue. The exposed section is connected to the support beam steel bar sleeve, and the other end is anchored into the top plate. The anchoring depth is 15 to 20 times the diameter of the steel bar.

[0018] Preferably, in the step S4, three bottom formwork reinforcement bars are implanted at each support beam position, the diameter of the reinforcement bars is 18 to 22 mm, and the reinforcement bars are positioned between the support piles and the outer wall of the basement, and 250 to 350 mm of support plate replacement reinforcement bars are tied.

[0019] Preferably, in step S5, a groove with a diameter of 35 to 45 mm and a depth of 10 to 20 mm is provided around the beam at a distance of 300 mm from the vertical surface of the underground structure.

[0020] Preferably, in step S6, 3+4 SBS waterproof membrane is constructed on the outer wall of the basement, an additional layer is added at the position of the support beam, and after the additional layer is completed, two waterproof layers are continued to be constructed to wrap the support beam, a metal strip is nailed into the groove of the support beam, and asphalt ointment is applied.

[0021] Preferably, in step S8, a 100 to 120 ton truck crane is used to tie up the steel beam in the middle and at one-third of both sides, and then the steel support is removed as a whole.

[0022] Preferably, in step S9, after the steel support is removed, a 110-ton truck crane is used to tie up the concrete beam in the middle and at one-third of both sides, and then the concrete support is removed as a whole.

[0023] The present invention provides a method for replacing supports during construction of an underground corridor under a deep foundation pit. It has the following beneficial effects:

[0024] 1. The present invention is suitable for large-space ultra-deep foundation pits with large depths and complex geological conditions, and can play a good role in different geological environments. Through reasonable construction measures, the stability and safety of the construction process can be guaranteed, and the occurrence of engineering accidents can be effectively prevented.

[0025] 2. The present invention is suitable for large-space ultra-deep foundation pits with large depths and complex geological conditions, and can play a good role in different geological environments. Through reasonable construction measures, the stability and safety of the construction process can be guaranteed, and the occurrence of engineering accidents can be effectively prevented.

[0026] 3. The present invention adopts standardized support replacement steps and mechanized operations to effectively improve construction efficiency, shorten construction period, and reduce labor costs and time investment in construction.

[0027] 4. The present invention makes full use of existing support materials, reduces resource waste, improves material turnover and utilization, and reduces engineering costs by rationally designing the support structure and the support replacement process.

[0028] 5. During the construction process, the present invention ensures the waterproof quality of the underground corridor structure by setting up multi-layer waterproof measures and anti-leakage treatment of special parts, avoiding structural damage and inconvenience caused by leakage during subsequent use. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of installation of a support replacement plate in the support replacement method for construction of an underground corridor under a deep foundation pit of the present invention;

[0030] Figure 2 The present invention is a flow chart of a method for replacing supports in construction of an underground corridor under a deep foundation pit.

[0031] Among them, 1. Replace the support plate; 2. Plant reinforcement; 3. Exterior wall of the basement. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Please see attached Figure 1 and attached Figure 2 The embodiment of the present invention provides a method for replacing supports during construction of an underground corridor under a deep foundation pit, comprising the following steps:

[0034] S1. Cantilever construction: Use steel pipe cantilever frame for support;

[0035] S2, positioning: positioning the top elevation line on the foundation pit support pile 6;

[0036] S3, reinforcing bar planting 2: implanting and anchoring reinforcing bars on the supporting piles 6;

[0037] S4, installation of the replacement support plate 1: installing the replacement support plate 1 at the support beam position;

[0038] S5. Anti-leakage treatment: grooves are set on the structural facade;

[0039] S6, membrane construction: construct waterproof membrane on the basement exterior wall 3, and add an additional layer at the support beam position;

[0040] S7, fertilizer tank backfill: After cleaning the garbage in the foundation pit, carry out waterproof protection layer construction and use fluidized solidified soil to backfill;

[0041] S8, Steel support removal: After the concrete reaches the required strength, use a truck crane to remove the steel support;

[0042] S9. Removal of concrete supports: After the steel supports are removed, use a truck crane to remove the concrete supports.

[0043] Specifically, this solution is suitable for large-space ultra-deep foundation pits with large depths and complex geological conditions, and can play a good role in different geological environments. Through reasonable construction measures, it can ensure the stability and safety of the construction process and effectively prevent the occurrence of engineering accidents.

[0044] In step S1, during cantilever construction, a steel pipe horizontal rod is used to firmly connect the top of the support pile 6. The return horizontal rod is 200 to 400 mm away from the main node, and the horizontal and vertical spacings are both 3 to 4 meters.

[0045] Specifically, in the cantilever construction process, in order to prevent the frame from shifting, the method uses a steel pipe horizontal rod and the top of the support pile 6 for a firm connection. The distance between the top horizontal rods should be maintained between 200 and 400 mm, and the horizontal spacing and vertical spacing should be maintained between 3 and 4 meters. Through a reasonable cantilever support design, the frame can be effectively prevented from shifting during the construction process, thereby improving the stability and safety of the structure.

[0046] In step S2, the top elevation line is measured along a position parallel to the top plate of the structure for every other supporting pile 6 on the foundation pit supporting pile 6.

[0047] Specifically, on the foundation pit support piles 6, every other support pile 6 is measured along the top elevation line in parallel with the top plate of the structure to ensure the accurate position of each support pile 6. Accurate positioning enables the subsequent steps of planting reinforcement 2, replacing support plate 1 installation, etc. to proceed more smoothly, reduce construction errors, and improve construction efficiency and quality.

[0048] In step S3, after positioning, rebar embedding 2 is performed on each foundation pit supporting pile 6. Each rebar embedding 2 contains 10 to 15 steel bars with a diameter of 18 to 22 mm. One end of the steel bar is anchored 250 to 350 mm into the pile and anchored with rebar embedding 2 glue. The exposed section is connected to the support beam steel bar sleeve and the other end is anchored into the top plate. The anchoring depth is 15 to 20 times the diameter of the steel bar.

[0049] Specifically, after positioning, each support pile 6 is subjected to a reinforcing bar planting operation 2, and 10 to 15 steel bars are required to be planted at each location, and the diameter of the steel bars is 18 to 22 mm. One end of the steel bar is anchored 250 to 350 mm into the pile, and anchored with reinforcing bar planting glue, and the exposed part is connected to the steel bar sleeve of the support beam. The other end is anchored into the top plate, and the anchoring depth is 15 to 20 times the diameter of the steel bar. The reinforcing bar planting operation 2 ensures a stable connection between the support pile 6 and the support beam, enhances the overall bearing capacity of the structure, and improves the safety and stability of the structure.

[0050] In step S4, three bottom formwork reinforcement bars with a diameter of 18 to 22 mm are implanted at each support beam position, and the reinforcement bars 2 are used to position the support piles 6 and the basement outer wall 3, and 250 to 350 mm of the replacement support plate 1 reinforcement bars are tied.

[0051] Specifically, a replacement support plate 1 needs to be installed at each support beam position. First, 3 base template support bars are implanted, with a steel bar diameter of 18 to 22 mm, and then the support piles 6 and the basement outer wall 3 are positioned by planting steel bars 2, and the replacement support plate 1 steel bars are tied to form a replacement support structure. The installation of the replacement support plate 1 increases the bearing capacity of the support structure, ensures the replacement support quality during the construction process, and thus improves the safety and efficiency of the construction.

[0052] In step S5, a groove with a diameter of 35 to 45 mm and a depth of 10 to 20 mm is set around the beam at a distance of 300 mm from the vertical surface of the underground structure.

[0053] Specifically, a groove is set at a distance of 300 mm from the facade of the underground structure. The diameter of the groove is 35 to 45 mm and the depth is 10 to 20 mm, which is used to close the waterproof layer. The anti-leakage treatment effectively prevents water from penetrating into the joints of the underground structure, improves the waterproof performance of the structure, and prolongs the service life of the underground building.

[0054] In step S6, 3+4SBS waterproof membrane is constructed on the basement exterior wall 3, and an additional layer is added at the support beam position. After the additional layer is completed, two waterproof layers are continued to be constructed to wrap the support beam, a metal strip is nailed into the groove of the support beam, and asphalt ointment is applied.

[0055] Specifically, waterproof membrane was constructed on the basement exterior wall 3, using the 3+4SBS waterproof membrane system, and an additional layer was added at the support beam position. After the additional layer was completed, two more waterproof layers were constructed to wrap the support beam. Metal strips were nailed into the grooves of the support beams, and asphalt ointment was applied on their surface.

[0056] Through multi-layer waterproofing construction, the waterproofing capacity of the basement exterior wall 3 and the supporting beams is enhanced, the possibility of basement leakage is reduced, and the durability and safety of the building are ensured.

[0057] In step S8, a 100 to 120 ton truck crane is used to tie up the steel beam in the middle and at one-third of each side, and then the steel support is removed as a whole.

[0058] Specifically, waterproofing membranes were constructed on the basement exterior wall 3, using the 3+4SBS waterproofing membrane system, and additional layers were added at the support beam position. After the additional layer was completed, two more waterproof layers were constructed to wrap the support beam. Metal strips were nailed into the grooves of the support beams, and asphalt paste was applied to their surfaces. Through multi-layer waterproofing construction, the waterproofing ability of the basement exterior wall 3 and the support beams was enhanced, the possibility of basement leakage was reduced, and the durability and safety of the building were ensured.

[0059] In step S9, after the steel support is removed, a 110-ton truck crane is used to tie up the concrete beam in the middle and at one-third of both sides, and then the concrete support is removed as a whole.

[0060] Specifically, after the steel support is removed, the concrete support is removed. A 110-ton truck crane is used to tie up the concrete beam in the middle and one-third of each side, and then the entire structure is removed. Reasonable removal of the concrete support ensures structural safety, reduces construction safety hazards caused by improper removal, and thus ensures smooth construction.

[0061] The following is an introduction in conjunction with specific embodiments:

[0062] S1. Cantilever construction

[0063] A 4-meter steel pipe is used as the cantilever frame, with a cantilever of 1.2 meters and an anchorage of 2.8 meters. The anchoring section uses two 20-diameter round steels for pre-embedded anchoring. The first one is no less than 300mm away from the anchoring end, and the second one is 200mm away from the third one.

[0064] The steel pipes buried in the shear wall need to be waterproofed and wrapped with a 20×30mm water-swellable waterstop strip. To ensure that the cantilevered steel pipe does not deform, a 32-diameter steel bar with a length of 4 meters is inserted into the steel pipe.

[0065] In order to prevent the frame from shifting, steel pipe horizontal rods are used to securely support the supporting piles 6. The horizontal rods at the top are no more than 300mm away from the main nodes. The horizontal spacing at the top is 3.6 meters and the vertical spacing is 3.6 meters.

[0066] After the external frame is removed, the steel pipe is cut off and filled with dry hard cement mortar. Then, 5mm thick steel plates are used to weld both sides of the pipe mouth firmly with an electric welder.

[0067] S2. Positioning

[0068] On the foundation pit support piles 6, every other support pile 6 is parallel to the structure top plate and measured for the top elevation line to ensure that the concrete support beam is on the same construction surface as the structure top plate after construction is completed.

[0069] S3, Rebar Planting 2

[0070] After positioning, according to the positioning line, embedding 2 is carried out on each supporting pile 6 of the foundation pit, with 12 φ20 steel bars at each location, one end of which is anchored 300mm into the pile. The steel bars are anchored into the supporting pile 6 with embedding glue, the exposed section is threaded and firmly connected to the support beam steel sleeve, and the other end is anchored into the top plate with a depth greater than 15d (d = steel bar diameter).

[0071] S4, Replace the support plate 1 and install

[0072] First, three bottom formwork reinforcement bars with a diameter of 20 need to be implanted at each supporting beam. Secondly, the embedded reinforcement bars 2 are used to position the support piles 6 and the basement outer wall 3, and 300*300 replacement support plate 1 reinforcement bars are tied out.

[0073] S5. Anti-leakage treatment

[0074] In order to prevent water leakage from overlapping the waterproof layer of the underground structure facade, it is necessary to make a 40×15mm diameter groove around the beam 300mm away from the structural facade (the waterproofing ends here)

[0075] S6. Coil construction

[0076] The basement exterior wall is made of 3+4 SBS waterproof membrane. If there is a supporting beam, add an additional layer at the connection between the beam and the structure. After the additional layer is completed, continue to construct two layers of waterproofing to wrap the supporting beam, nail metal strips in the reserved grooves of the supporting beam, and apply asphalt paste on the outside to ensure the waterproof quality and prevent leakage without risk.

[0077] S7, Fertilizer Tank Backfill

[0078] First, clean up the garbage in the foundation pit. Then, after the construction of the exterior wall waterproof protective layer is completed, continue to backfill the fluidized solidified soil. Please press Complete.

[0079] S8. Steel support removal

[0080] After the concrete strength reaches 100%, the steel support is removed. First, the middle connection point of the steel beam is tied to one-third of the position on both sides of the steel beam with a 110T truck crane, and the entire beam is removed.

[0081] S9, concrete support removal

[0082] After the steel support is removed, the demolition is carried out. First, use a 110T truck crane to tie up the middle connection point of the beam at one-third of the position on both sides, and then remove the entire beam.

[0083] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for replacing supports during construction of an underground corridor under a deep foundation pit, characterized in that: The following steps are involved: S1. Cantilever construction: Use steel pipe cantilever frame for support; S2. Positioning: Position the top elevation line on the foundation pit support piles; S3, planting reinforcement: planting reinforcement on the supporting piles and anchoring them; S4, installation of replacement support plate: installation of replacement support plate at the support beam position; S5. Anti-leakage treatment: grooves are set on the structural facade; S6. Membrane construction: waterproof membrane is constructed on the basement exterior wall and additional layers are added at the support beam position; S7, fertilizer tank backfill: After cleaning the garbage in the foundation pit, carry out waterproof protection layer construction and use fluidized solidified soil to backfill; S8, Steel support removal: After the concrete reaches the required strength, use a truck crane to remove the steel support; S9. Removal of concrete supports: After the steel supports are removed, use a truck crane to remove the concrete supports.

2. The method for replacing supports during construction of an underground corridor under a deep foundation pit according to claim 1, characterized in that: In the step S1, during cantilever construction, a steel pipe horizontal rod is used to firmly connect the top of the supporting pile. The top return horizontal rod is 200 to 400 mm away from the main node, and the horizontal and vertical spacings are both 3 to 4 meters.

3. A method for replacing supports during construction of an underground corridor under a deep foundation pit according to claim 1, characterized in that: In the step S2, the top elevation line is measured along a position parallel to the top plate of the structure for every other supporting pile on the foundation pit supporting pile.

4. The method for replacing support during construction of underground corridor under deep foundation pit according to claim 1, characterized in that: In the S3 step, after positioning, reinforcement is planted on each foundation pit supporting pile. Each reinforcement contains 10 to 15 steel bars with a diameter of 18 to 22 mm. One end of the steel bar is anchored 250 to 350 mm into the pile and anchored with reinforcement glue. The exposed section is connected to the support beam steel sleeve and the other end is anchored into the top plate. The anchoring depth is 15 to 20 times the diameter of the steel bar.

5. The method for replacing supports during construction of an underground corridor under a deep foundation pit according to claim 1, characterized in that: In the step S4, three bottom formwork reinforcement bars with a diameter of 18 to 22 mm are implanted at each support beam position, and the reinforcement bars are positioned between the support piles and the basement outer wall, and 250 to 350 mm of support plate replacement reinforcement bars are tied.

6. The method for replacing support during construction of underground corridor under deep foundation pit according to claim 1, characterized in that: In the step S5, a groove with a diameter of 35 to 45 mm and a depth of 10 to 20 mm is provided around the beam at a distance of 300 mm from the vertical surface of the underground structure.

7. The method for replacing supports during construction of an underground corridor under a deep foundation pit according to claim 1, characterized in that: In the step S6, 3+4 SBS waterproof membrane is constructed on the outer wall of the basement, and an additional layer is added at the position of the support beam. After the additional layer is completed, two waterproof layers are continuously constructed to wrap the support beam, a metal strip is nailed into the groove of the support beam, and asphalt ointment is applied.

8. The method for replacing supports during construction of an underground corridor under a deep foundation pit according to claim 1, characterized in that: In the step S8, a 100 to 120 ton truck crane is used to tie up the steel beam in the middle and at one-third of both sides, and then the steel support is removed as a whole.

9. The method for replacing supports during construction of an underground corridor under a deep foundation pit according to claim 1, characterized in that: In the step S9, after the steel support is removed, a 110-ton truck crane is used to tie the concrete beam in the middle and at one-third of both sides, and then the concrete support is removed as a whole.

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