A construction method for a jacking pipe to pass through an obstacle under a caisson

Abstract

The present invention discloses a construction method for jacking pipes through an obstruction caisson. The method comprises the following steps: removing the accessories of the original pipe jacking machine, leaving only the casing; reversing the direction of the newly arrived pipe jacking machine from the original receiving well to enter the obstruction caisson; removing the accessories of the newly arrived pipe jacking machine, leaving only the casing; and welding the casings of two pipe jacking machines below the obstruction caisson, so that the casings of the two pipe jacking machines serve as outer casings. The present invention can pierce the obstruction caisson without damaging the gas pipeline, national defense optical cable, water pipeline, or other underground pipelines above it, thereby enabling smooth pipe jacking construction.

Description

Technical Field

[0001] The invention belongs to the technical field of pipe jacking construction, and in particular relates to a construction method for a caisson with a pipe jacking passing through an obstacle. Background Art

[0002] Currently, pipe jacking construction typically utilizes a tunnel boring machine (TBM) to excavate the soil. The machine's end cuts and mixes the soil, then discharges it as a slurry. During the pipe jacking process, the jacking force may suddenly increase when jacking a particular casing (for example, when jacking the 50th casing, the jacking force suddenly increases from 320 tons to 450 tons). This can lead to the appearance of formwork fragments, rebar wire, and concrete debris at the discharge port, making pipe jacking difficult and causing the machine head to vibrate violently. Technicians investigated and discovered that this was caused by the machine hitting an obstruction caisson (the jacking machine head was located below the blade foot of the obstruction caisson), causing damage to the machine. (The existing machine (#1) located below the obstruction caisson had several components, except for the cutter, scraper, and bracket, severely damaged and unable to be repaired on-site.) The concrete and gravel surrounding the machine needed to be cleared, and the machine disassembled on-site and returned to the factory for repair before proceeding with the pipe jacking construction. However, above the obstruction caisson, there are often underground pipelines such as gas pipelines, defense optical cables, and water pipes. Using conventional methods to remove the obstruction caisson for pipe jacking construction could damage these pipelines, which is unacceptable. Therefore, conventional methods to remove the obstruction caisson for pipe jacking cannot be used. Instead, a pipe jacking method that penetrates the obstruction caisson is required. Summary of the Invention

[0003] The purpose of the present invention is to provide a construction method for jacking pipes through an obstacle caisson. The method can pierce the obstacle caisson without damaging the gas pipelines, national defense optical cables, water pipelines and other underground pipelines above it, so that the jacking pipe construction can proceed smoothly.

[0004] The technical solution adopted in the present invention is:

[0005] A construction method for jacking pipes through an obstacle caisson is disclosed. The method comprises the following steps: removing the accessories of the original pipe jacking machine, leaving only the casing; reversing the direction of the newly arrived pipe jacking machine from the original receiving well to enter the obstacle caisson; removing the accessories of the newly arrived pipe jacking machine, leaving only the casing; and welding the casings of the two pipe jacking machines together below the obstacle caisson, so that the casings of the two pipe jacking machines serve as outer casings. The method specifically comprises the following steps:

[0006] 1) Remove the reinforced concrete from the side of the caisson where the pipe jacking operation is not to be carried out, and dig a construction hole at that location;

[0007] 2) A support structure is set up on the side of the obstacle caisson where the jacking operation is not carried out. The support structure is located on the same side as the construction hole;

[0008] 3) Set up pipe wells around the obstacle caisson;

[0009] 4) Remove the concrete at the edge of the obstacle caisson; reinforce the soil at the edge of the obstacle caisson with a water-stop curtain;

[0010] 5) In the direction of the original pipe jacking machine head, a second high-pressure jet grouting pile is set up in the soil outside the obstacle caisson to reinforce the water-stop curtain, and the second high-pressure jet grouting pile is placed under the machine head;

[0011] On the opposite side of the support structure, a third high-pressure jet grouting pile is provided near the machine head;

[0012] 6) Remove the wall and bottom plate of the caisson;

[0013] 7) Remove the accessories of the original pipe jacking machine and leave only the casing;

[0014] 8) The newly entered pipe jacking machine returns from the original receiving well and enters the bottom of the obstacle caisson;

[0015] 9) Remove the accessories of the newly arrived pipe jacking machine, leaving only the casing; weld the casings of the two pipe jacking machines under the obstacle caisson, so that the casings of the two pipe jacking machines serve as outer casings;

[0016] 10) Tie steel bars on the outer casing and pour concrete to form a closed jacking shell;

[0017] 11) Tie steel bars to support the formwork at the construction hole, pour concrete to restore the original shape, and complete the caisson construction under the jacking pipe to pass through the obstacle.

[0018] According to the above scheme, in step 1), the bottom of the construction hole is 0.1-0.3m away from the bottom of the head of the original pipe jacking machine.

[0019] According to the above scheme, in step 2), the support structure includes a first Larsen steel sheet pile unit, a second Larsen steel sheet pile unit, a third Larsen steel sheet pile unit, and a fourth Larsen steel sheet pile unit; the first Larsen steel sheet pile unit, the second Larsen steel sheet pile unit, and the third Larsen steel sheet pile unit are connected in sequence to form a U-shaped structure; the first Larsen steel sheet pile unit is connected to the wall of the obstacle caisson through a first steel pipe support and a first steel pipe diagonal brace respectively; the second Larsen steel sheet pile unit is connected to the first Larsen steel sheet pile unit through a second steel pipe diagonal brace, the second Larsen steel sheet pile unit is connected to the third Larsen steel sheet pile unit through a third steel pipe diagonal brace, and the second Larsen steel sheet pile unit is connected to the support rod in the obstacle caisson through a second steel pipe support; the fourth Larsen steel sheet pile unit is placed in the second Larsen steel sheet pile unit, 1.2-1.7m away from the outer wall of the obstacle caisson.

[0020] According to the above scheme, in step 3), the construction method of the pipe well is: preparation for pipe well construction → positioning of the well point position → drilling rig to form a hole → hole cleaning and well washing → well pipe installation → hole wall sand filling → water pump installation → water quality and water quantity inspection → test pumping → normal pumping → well point pipe removal → well hole backfilling treatment.

[0021] According to the above scheme, in step 4), the method for reinforcing the soil on the blade angle side of the obstacle caisson with a water-stop curtain is: setting a first high-pressure rotary jet pile on the side of the obstacle caisson where no jacking operation is performed, and performing compaction grouting; the reinforced width is 1.0-1.5m, the length is 6.7-7.6m, and the depth is 9.5-10.5m.

[0022] According to the above scheme, in step 5), after the third high-pressure rotary jet pile is set on the opposite side of the support structure, near the machine head, the concrete bottom plate of the obstacle caisson on the side of the original pipe jacking machine head and the wall of the obstacle caisson that has been removed above the machine head are supported vertically by angle steel, which can effectively prevent the upper part of the hole and the surrounding soil layer from collapsing when the jacking pipe is returned and the machine head is removed; a sand layer is set under the original pipe jacking machine head, and the sand layer is connected to the wall of the obstacle caisson.

[0023] According to the above scheme, the construction process for breaking the wall and bottom plate of the obstacle caisson in step 6) is as follows: excavation of the outer side of the obstacle caisson is completed → measurement and layout are carried out to define the range of the wall to be broken → sewage is diverted in the original sewage pipe → a hydraulic breaker is used to break the wall to the elevation of the foundation pit excavation outside the well → steel bars in the wall are cut → the bottom plate is broken by a breaker → concrete blocks are removed and transported out → the bottom plate is manually broken using a jackhammer to the elevation of the bottom of the machine head → concrete blocks are removed and transported out → a hole is drilled in the wall to break the wall in the direction of the top pipe axis.

[0024] According to the above scheme, in step 7), when the cutter head of the original pipe jacking machine is removed, high-pressure rotary jet piles are used to carry out anti-seepage sealing construction on the bottom and side walls of the obstacle caisson. The process is: measurement and positioning → vibration drilling machine is in place → grouting head is added before the end of the first section of the grouting pipe is buried in the soil → a 2.2kw vibration motor is used to press the Φ25mm special black iron grouting pipe into the soil, leaving 100mm at the top → the second drill rod is connected and pressed into the soil to the designed height → grouting, the grouting pressure is controlled within 0.2-0.4mpa, and the slurry flow rate is 0.45L / min → grouting and lifting from bottom to top.

[0025] According to the above scheme, in step 7), the accessories include detachable parts such as the correction valve group, grease pump, electrical box, hydraulic pump station, mud water system, correction cylinder, cables, oil pipes, etc.

[0026] According to the above scheme, in step 8), a fourth high-pressure rotary jet pile is arranged outside the well wall on the anti-top direction side of the original receiving well; a fifth high-pressure rotary jet pile is arranged outside the well wall on the rear backrest side of the original receiving well; this can avoid the well wall of the receiving well from cracking due to uneven load limit when the hydraulic jack is pushed forward with maximum top force; the rear backrest mainly bears the reaction force when the oil cylinder is pushed forward, and transmits it evenly to the well wall of the original receiving well, avoiding the well wall from cracking due to uneven force.

[0027] According to the above scheme, in step 8), during the return of the newly entered pipe jacking machine, a certain amount of drag-reducing mud is injected into the outer wall of the section through the grouting ring pipe.

[0028] A further solution is to use multi-point symmetrical injection in step 8 to evenly fill the gaps between the outer wall of the jacking pipe and the surrounding soil with the drag-reducing slurry, thereby reducing the frictional resistance between the jacking pipe and the soil and reducing the return resistance.

[0029] The beneficial effects of the present invention are:

[0030] By welding the casings of two pipe jacking machines under the obstacle caisson, the pipe jacking can pass through the obstacle caisson without damaging the gas pipeline, national defense optical cable, water pipeline and other underground pipelines above it, so that the pipe jacking construction can proceed smoothly.

[0031] Setting up a support structure on the side of the obstacle caisson where the jacking operation is not being carried out can effectively prevent the soil layer above the hole from collapsing when the jacking operation is carried out.

[0032] The soil on the blade corner of the obstacle caisson is reinforced with a water-stop curtain to prevent the mud and sand outside the obstacle caisson from flowing into the obstacle caisson;

[0033] Setting up pipe wells around the obstacle caisson can effectively prevent large amounts of water from gushing out of the hole when the jacking pipe is returned and the jacking machine is removed;

[0034] High-pressure jet grouting piles are set at the bottom of the machine head to reinforce the water-stop curtain, which can prevent the sand and gravel at the bottom of the obstacle caisson from flowing under the action of groundwater. At the same time, the high-pressure jet grouting piles can also provide a working surface for dismantling the machine head.

[0035] The water-stop curtain is reinforced on the outside of the obstacle caisson through various supports and the soil outside the well wall, making the jacking pipe structure more stable and reliable; it can enhance the strength of the pipe end and evenly transmit the jacking force between the jacking pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0037] Figure 1 It is a planar structural diagram of the support structure;

[0038] Figure 2 It is the construction plan of the obstacle caisson;

[0039] Figure 3 This is a construction cross-section of the obstacle caisson;

[0040] Figure 4 This is the plan view of the soil reinforcement of the original receiving well with high-pressure jet grouting piles;

[0041] In the figure, 1. Obstacle caisson, 2. Original receiving well, 3. First Larsen steel sheet pile unit, 4. Second Larsen steel sheet pile unit, 5. Third Larsen steel sheet pile unit, 6. First steel pipe support, 7. First steel pipe diagonal brace, 8. Second steel pipe diagonal brace, 9. Third steel pipe diagonal brace, 10. Second steel pipe support, 11. Third high-pressure rotary jet pile, 12. Angle steel, 13. Sand layer, 14. Original pipe jacking machine, 15. Well wall, 16. Fourth high-pressure rotary jet pile, 17. Fifth high-pressure rotary jet pile, 18. Second high-pressure rotary jet pile, 19. Backrest, 20. Support rod, 21. New pipe jacking machine, 22. Fourth Larsen steel sheet pile unit, 23. First high-pressure rotary jet pile. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0043] See also Figures 1-4 A construction method for jacking pipes through an obstacle caisson is provided. The method comprises the following steps: removing the accessories of the original pipe jacking machine 14, leaving only the casing; reversing the jacking of the newly arrived pipe jacking machine 21 from the original receiving well 22 to enter the bottom of the obstacle caisson 1; removing the accessories of the newly arrived pipe jacking machine 21, leaving only the casing; and welding the casings of the two pipe jacking machines together under the obstacle caisson, so that the casings of the two pipe jacking machines serve as outer casings. The method specifically comprises the following steps:

[0044] 1) Remove the reinforced concrete from the side of the obstruction caisson 1 where the pipe jacking operation will not be performed. A 3m x 2.5m construction hole is dug at this location, with the bottom of the construction hole 0.2m from the bottom of the original pipe jacking machine 14. The original ground elevation at the obstruction caisson 1 is 69.90m, and the original elevation of the bottom of the pipe jacking machine 14 is 58.00m. The excavation depth of the construction hole is 12.10m.

[0045] 2) A support structure is set up on the side of the obstacle caisson 1 where the jacking operation is not performed, and the support structure is located on the same side as the construction hole; the support structure includes a first Larsen steel sheet pile unit 3, a second Larsen steel sheet pile unit 4, a third Larsen steel sheet pile unit 5, and a fourth Larsen steel sheet pile unit 22; the first Larsen steel sheet pile unit 3, the second Larsen steel sheet pile unit 4, and the third Larsen steel sheet pile unit 5 are connected in sequence to form a U-shaped structure; the first Larsen steel sheet pile unit 3 is supported by a first steel pipe 6, a second Larsen steel sheet pile unit 4, and a third Larsen steel sheet pile unit 5. A steel pipe brace 7 is connected to the wall 15 of the obstacle caisson 1. The second Larsen steel sheet pile unit 4 is connected to the first Larsen steel sheet pile unit 3 via a second steel pipe brace 8. The second Larsen steel sheet pile unit 4 is connected to the third Larsen steel sheet pile unit 5 via a third steel pipe brace 9. The second Larsen steel sheet pile unit 4 is connected to the support rod 20 inside the obstacle caisson 1 via a second steel pipe support 10. The fourth Larsen steel sheet pile unit 22 is placed inside the second Larsen steel sheet pile unit 4, 1.5 meters from the outer wall of the obstacle caisson 1. The first, second, and third Larsen steel sheet pile units 3, 4, and 5 are 12-meter-long FSP-IV type Larsen steel sheet piles, and the fourth Larsen steel sheet pile unit 22 consists of fifteen 6-meter-long pieces. The FSP-IV type Larsen steel sheet piles are supported by 350*350*20*20 I-beams. The steel pipe supports and braces are ￠230*10 steel pipes.

[0046] 3) Ten 26m deep pipe wells are set up around the obstacle caisson 1. The pipe well construction process is as follows: pipe well construction preparation → well point location layout → drilling rig hole → hole cleaning and well washing → well pipe installation → hole wall sand filling → water pump installation → water quality and water quantity inspection → test pumping → normal pumping → well point pipe removal → well hole backfilling.

[0047] 4) Remove the concrete at the blade corner of obstacle caisson 1; reinforce the soil on the blade corner side of obstacle caisson 1 with a water-stop curtain to prevent the sand and gravel at the bottom of the obstacle caisson from becoming quicksand under the action of groundwater, while providing a working surface for the demolition head; wherein, the method for reinforcing the soil on the blade corner side of obstacle caisson 1 with a water-stop curtain is as follows: set a first high-pressure jet grouting pile 23 on the side of obstacle caisson 1 where the jacking operation is not performed, and perform compaction grouting; the reinforced width is 1.2m, the length is 7.2m, and the depth is 9.9m.

[0048] 5) In the jacking direction of the original pipe jacking machine 14, a second high-pressure jet grouting pile 18 is set in the soil outside the obstacle caisson 1 to reinforce the water-stop curtain, and the second high-pressure jet grouting pile 18 is placed under the machine head;

[0049] On the opposite side of the support structure, after the third high-pressure rotary jet pile 11 is set near the machine head, the concrete bottom plate of the obstacle caisson 1 on the side of the original pipe jacking machine 14 head and the well wall 15 of the obstacle caisson 1 that has been broken above the machine head are vertically supported by 70*5@50cm angle steel 12; a sand layer 13 is set under the head of the original pipe jacking machine 14, and the sand layer 13 is connected to the well wall 15 of the obstacle caisson 1.

[0050] 6) Remove the obstacle caisson 1 wall 15 and bottom plate, and the construction process is as follows: complete the excavation of the outer side of the caisson → measure and lay out, and define the range of the wall to be removed → divert the sewage in the original sewage pipe (DN1500) → use a 220-type excavator to replace a hydraulic breaker to remove the wall to the excavation elevation of the foundation pit outside the well → manually cut the steel bars in the wall with oxygen welding → replace the 30-type micro excavator with a breaker to manually cooperate in removing the bottom plate → remove and transport the concrete blocks → manually use a jackhammer to break the bottom plate to the elevation of the bottom of the machine head → remove and transport the concrete blocks → drill a hole in the wall and remove the wall in the direction of the top pipe axis.

[0051] 7) Remove the accessories of the original pipe jacking machine 14, leaving only the casing; when the cutter head of the original pipe jacking machine 14 is removed, use high-pressure rotary jet piles to carry out anti-seepage sealing construction on the bottom and side walls of the obstacle caisson 1. The process is: measure and lay out the positioning → put the vibration drilling machine in place → add the grouting head before the end of the first section of the grouting pipe is buried in the soil → use a 2.2kw vibration motor to press the Φ25mm special black iron grouting pipe into the soil, leaving 100mm at the top → connect the second drill rod and press it into the soil to the designed height → grouting, the grouting pressure is controlled within 0.2-0.4mpa, the slurry flow rate is 0.45L / min → grouting and lifting from bottom to top.

[0052] The steps for removing the accessories of the original pipe jacking machine 14 are as follows: first remove the correction valve group, grease pump, electrical box, hydraulic pump station, mud and water system, correction cylinder, cable, and oil pipe inside the machine head; cut the cutter head along the cutting line and remove the cutter head; hang the power system with a half-mounted rope, and then cut it inward along the cutting line with a diameter of 2600m from the outside of the mud bin to remove the power system.

[0053] 8) The newly arrived pipe jacking machine 21 (2.6m in diameter) reverses from the original receiving well 2 and enters under the obstacle caisson 1; when the original receiving well 2 serves as the starting well for the second reverse return, a fourth high-pressure rotary jet grouting pile 16 is installed outside the well wall on the reverse-top direction side of the original receiving well 2; a fifth high-pressure rotary jet grouting pile 17 (68 Φ600@550) is installed outside the well wall on the rear backrest 19 side of the original receiving well 2 to reinforce the soil behind the rear backrest wall.

[0054] The construction area of the original receiving shaft 2 was enclosed with a 2.5m-high PVC fence. The construction access road was backfilled with 50cm-thick brick slag, and paved with a 20cm-thick C25 concrete surface. Three tertiary sedimentation tanks, measuring 10m x 10m x 2.5m, were installed on site. A 1.2m-high safety guardrail was installed around the upper opening of the working shaft using standardized guardrail steel pipes welded together.

[0055] The rear backrest measures 2.0×2.0m and is primarily used to withstand the reaction force from the oil cylinder during jacking, transferring it evenly to the wall of the original receiving well 2 to prevent cracking due to uneven force. The verticality of the rear backrest 19 itself and its perpendicularity to the axis are also crucial for future jacking. The rear backrest should be installed according to the actual jacking axis and should remain perpendicular to the jacking axis. The installation elevation deviation should not exceed 10mm, and the horizontal deviation should not exceed 10mm. After the rear backrest is positioned, the gap between it and the well wall should be filled and compacted with plain concrete.

[0056] During the return jacking process of the newly arrived pipe jacking machine 21, a certain amount of drag-reducing mud is injected into the outer wall of the section through the grouting ring. Multi-point symmetrical injection is used to evenly fill the gaps between the outer wall of the jacking pipe and the surrounding soil. This reduces friction between the jacking pipe and the soil, thus reducing the resistance to return jacking. The drag-reducing mud ratio is: bentonite: 50kg, soda ash: 5kg, CMC: 1.2kg, water: 550kg.

[0057] 9) The accessories of the newly arrived pipe jacking machine 21 are removed, leaving only the casing; the casings of the two pipe jacking machines are welded below the obstacle caisson 1, so that the casings of the two pipe jacking machines serve as outer casings.

[0058] 10) Tie steel bars on the outer casing and pour concrete to form a closed jacking shell;

[0059] 11) Tie steel bars to support the formwork at the construction hole, pour concrete to restore the original shape, and complete the caisson construction under the jacking pipe to pass through the obstacle.

[0060] 12) After the pipeline is fully constructed, a strength and tightness test will be carried out using a water pressure test method with a working pressure of 0.6MPa and a test pressure of 0.9MPa. Other test standards, requirements and test procedures shall comply with national acceptance specifications and the pipeline may only be used after passing the test.

[0061] In the present invention, in order to improve the working environment in the pipeline, a composite ventilation measure is adopted during construction, that is, air is pressed into the machine head from the outside through a vortex fan through a 300mm rubber ventilation pipe, and air is forced to be exhausted in the pipeline and the well through an axial flow fan.

[0062] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A construction method for a caisson with a jacking pipe passing through an obstacle, characterized by: Remove the original pipe jacking machine's accessories, leaving only the casing; the newly arrived pipe jacking machine is reversed from the original receiving well and pushed under the obstacle caisson; remove the new pipe jacking machine's accessories, leaving only the casing; weld the casings of the two pipe jacking machines under the obstacle caisson, making the casings of the two pipe jacking machines serve as outer casings; specifically: 1) Chisel away the reinforced concrete on the side of the caisson where the pipe jacking operation will not be carried out, and dig a construction hole at that location; 2) A support structure is set up on the side of the obstacle caisson where the jacking operation is not carried out. The support structure is located on the same side as the construction hole; 3) Set up pipe wells around the obstacle caisson; 4) Remove the concrete at the corner of the caisson that is an obstacle; The soil on the blade corner side of the obstacle caisson is reinforced with a water-stop curtain; 5) In the direction of the original pipe jacking machine head, a second high-pressure jet grouting pile is set up in the soil outside the obstacle caisson to reinforce the water-stop curtain, and the second high-pressure jet grouting pile is placed under the machine head; On the opposite side of the support structure, a third high-pressure jet grouting pile is provided near the machine head; 6) Remove the obstruction wall and bottom plate of the caisson; 7) Remove the accessories of the original pipe jacking machine, leaving only the casing; 8) The newly arrived pipe jacking machine moves back from the original receiving well and enters the caisson below the obstacle; 9) Remove the accessories of the newly arrived pipe jacking machine, leaving only the casing; weld the casings of the two pipe jacking machines under the obstacle caisson, so that the casings of the two pipe jacking machines serve as outer casings; 10) Tie steel bars to the outer casing and pour concrete to form a closed jacking shell; 11) Tie steel bars to support the formwork at the construction hole, pour concrete to restore the original shape, and complete the caisson construction under the jacking pipe to pass through the obstacle.

2. The construction method for a caisson with a jacking pipe passing through an obstacle according to claim 1, characterized in that: In step 1), the bottom of the construction hole is 0.1-0.3m away from the bottom of the head of the original pipe jacking machine.

3. The construction method for a caisson with a jacking pipe passing through an obstacle according to claim 1, characterized in that: In step 2), the support structure includes a first Larsen steel sheet pile unit, a second Larsen steel sheet pile unit, a third Larsen steel sheet pile unit, and a fourth Larsen steel sheet pile unit; the first Larsen steel sheet pile unit, the second Larsen steel sheet pile unit, and the third Larsen steel sheet pile unit are connected in sequence to form a U-shaped structure; the first Larsen steel sheet pile unit is connected to the wall of the obstacle caisson through a first steel pipe support and a first steel pipe diagonal brace, respectively; the second Larsen steel sheet pile unit is connected to the first Larsen steel sheet pile unit through a second steel pipe diagonal brace, the second Larsen steel sheet pile unit is connected to the third Larsen steel sheet pile unit through a third steel pipe diagonal brace, and the second Larsen steel sheet pile unit is connected to the support rod in the obstacle caisson through a second steel pipe support; the fourth Larsen steel sheet pile unit is placed in the second Larsen steel sheet pile unit, 1.2-1.7 m away from the outer wall of the obstacle caisson.

4. The construction method for caisson with pipe jacking and passing through obstacles according to claim 1 is characterized in that: In step 4), the soil on the blade angle side of the obstacle caisson is reinforced with a water-stop curtain by setting a first high-pressure jet grouting pile on the side of the obstacle caisson where the jacking operation is not performed, and performing compaction grouting; the reinforcement width is 1.0-1.5 m, the length is 6.7-7.6 m, and the depth is 9.5-10.5 m.

5. The construction method of a caisson with a jacking pipe passing through an obstacle according to claim 1, characterized in that: In step 5), after the third high-pressure jet grouting pile is set near the machine head on the opposite side of the support structure, angle steel is used for vertical support of the concrete bottom plate of the obstacle caisson on the side of the original pipe jacking machine head and the wall of the obstacle caisson above the machine head that has been broken; a sand layer is set under the original pipe jacking machine head, and the sand layer is connected to the wall of the obstacle caisson.

6. The construction method for caisson with pipe jacking and passing through obstacles according to claim 1 is characterized in that: The construction process for breaking the wall and bottom plate of the obstacle caisson in step 6) is as follows: complete the excavation of the outer side of the obstacle caisson → measure and lay out the lines, and define the area of the wall to be broken → divert the sewage in the original sewage pipe → use a hydraulic breaker to break the wall to the excavation elevation of the foundation pit outside the well → cut the steel bars in the wall → break the bottom plate with a breaker → remove the concrete blocks → manually use a jackhammer to break the bottom plate to the elevation of the bottom of the machine head → remove the concrete blocks → use a water drill to drill a hole in the wall and break the wall in the direction of the top pipe axis.

7. The construction method for caisson with pipe jacking and passing through obstacles according to claim 1 is characterized in that: In step 7), when the cutter head of the original pipe jacking machine is removed, high-pressure jet grouting piles are used to carry out anti-seepage sealing construction on the bottom and side walls of the obstacle caisson.

8. The construction method for a caisson with a pipe jacking and passing through an obstacle according to claim 1, characterized in that: In step 8), a fourth high-pressure rotary jet pile is arranged outside the well wall on the reverse return direction side of the original receiving well; and a fifth high-pressure rotary jet pile is arranged outside the well wall on the rear back side of the original receiving well.

9. The construction method for caisson with pipe jacking and passing through obstacles according to claim 1, characterized in that: In step 8), during the reverse return of the newly entered pipe jacking machine, multi-point symmetrical injection is used to evenly fill the gaps between the outer wall of the pipe jacking and the surrounding soil with the drag-reducing slurry.

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