Construction method for breaking high-strength obstacles through pipe jacking machine capable of retracting

Abstract

The invention discloses a construction method for breaking high-strength obstacles through a retractable pipe jacking machine. The construction method comprises the following steps that an originating well is formed through excavation; arranging a pipe jacking machine capable of retreating at the bottom of the originating well; when encountering a high-strength obstacle in the jacking process, the pipe jacking machine retracts the cutter teeth to enable the outer diameter of the pipe jacking machine to be smaller than that of the tool pipe, and the pipe jacking machine retreats to the originating well to form an obstacle clearing space; an obstacle removing device is installed, during obstacle removing operation, a main jacking oil cylinder jacks the obstacle removing device forwards, meanwhile, a power system is connected with a drill rod to drive an outer shell to rotate, and an alloy cutter on the outer shell integrally cuts an obstacle and wraps the obstacle into the outer shell; the outer shell of the obstacle clearing device wraps the obstacle, the whole outer shell and the obstacle are dragged back to the starting well from the rear steel pipe, obstacle clearing is achieved, and the pipe jacking machine continues to conduct jacking work till the whole jacking work is completed. The front high-strength obstacle can be taken out integrally in the jacking direction, the obstacle removing construction risk is greatly reduced, and the construction efficiency of the pipe jacking machine is improved.

Description

Technical Field

[0001] This invention relates to the field of tunnel engineering technology, and in particular to a construction method for using a retractable pipe jacking machine to break through high-strength obstacles. Background Technology

[0002] With the densification of underground pipeline networks, steel pipe jacking encounters high-strength obstacles during the jacking process, such as boulders, reinforced concrete pile foundations, and diaphragm walls. Because small pipe jacking machines have limited torque and thrust, and these high-strength obstacles differ from materials like clay, they cannot directly cut through them, hindering the application and promotion of pipe jacking methods. In existing technologies, when small pipe jacking machines encounter high-strength obstacles, they are often first retracted from the steel pipe to the starting position, and then manually removed from the pipe. While this method solves the engineering problem, it involves manual removal in confined spaces, using heavy-duty removal devices like pneumatic picks inside the pipe, and then manually removing the obstacle using hoisting equipment or by hand. Furthermore, the quality of manual removal is difficult to guarantee, resulting in obstacle residue and irregular boundaries, affecting subsequent jacking accuracy. Manual removal is high-risk, unsafe, inefficient, and time-consuming.

[0003] Therefore, the above problems urgently need to be solved. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a construction method for removing high-strength obstacles using a retractable pipe jacking machine. This method enables the removal of high-strength obstacles along the jacking direction, greatly reducing the risk of obstacle removal and improving the construction efficiency of the pipe jacking machine.

[0005] Technical Solution: To achieve the above objectives, this invention discloses a construction method for using a retractable pipe jacking machine to break through high-strength obstacles, comprising the following steps: (1) Excavate the foundation pit, implement reinforcement measures in the foundation pit, and pour the structural base plate to form the starting well of the pipe jacking machine; construct the guide wall in the jacking direction and the reaction wall on the corresponding side; (2) A pipe jacking machine workbench that can move left, right, up and down is arranged at the bottom of the starting well, and a pipe jacking machine that can retract is arranged on the pipe jacking machine workbench. (3) During the jacking process, the main jacking cylinder pushes the jacking machine head into the soil through the mud inlet and outlet pipes along the jacking direction to realize the front section of tunneling; reset the main jacking cylinder, hoist the first section of steel pipe, and repeat the steel pipe jacking process after jacking the first section of steel pipe until a high-strength obstacle is encountered; (4) The pipe jacking machine retracts its cutting teeth so that the outer diameter of the pipe jacking machine is smaller than the tool pipe at the front end, and the pipe jacking machine retracts to the starting well to form a clearing space; (5) Install a clearing device. The clearing device includes a power system connected to the main jacking cylinder, a drill rod connected to the output shaft of the power system, a drag-reducing support device that passes through the drill rod and is used to stabilize the jacking posture, and a clearing shell fixed to the front end of the drill rod. The clearing shell includes an outer shell, alloy cutter heads that are evenly distributed around the front end of the outer shell, a partition plate inside the outer shell, a nozzle on the partition plate that sprays towards the alloy cutter heads, and a bottom plate at the rear end of the outer shell that is fixed to the front end of the drill rod. The partition plate, the outer shell and the bottom plate form a cavity for storing water. Water injection holes and pressurization holes are provided on the outer shell corresponding to the cavity. (6) During the obstacle clearing operation, the main jacking cylinder pushes the obstacle clearing device forward, and at the same time, the power system connects to the drill rod to drive the outer shell to rotate. The alloy cutter on the outer shell cuts the obstacle as a whole and then wraps the obstacle inside the outer shell. After one jacking is completed, the main jacking cylinder and power system are restored, and the next section of drill rod is bolted on. At the same time, a drag reduction support device is arranged to carry out the next jacking obstacle clearing operation. During the obstacle clearing process, high-pressure water is used to rinse and cool the alloy cutter. (7) The outer shell of the obstacle removal device wraps the obstacle and drags the entire outer shell along with the obstacle back to the starting well from the rear steel pipe to remove the obstacle. The dragging operation is the opposite of the jacking operation. Each time the drill rod is retracted, it is removed until the outer shell and the obstacle are dragged out together. (8) After the obstacle is cleared, the pipe jacking machine continues to jacking, repeating step (3). If an obstacle is encountered again, repeat steps (4) to (7) until the entire jacking operation is completed.

[0006] Optionally, in step (1), the soil around the retaining piles is first reinforced by pre-grouting. Then, laser theodolite measurements are taken based on the starting shaft and the direction of pipe jacking to determine the jacking axis and center position. According to the measurement results, guide pipes are pre-embedded in the direction of pipe jacking. After checking the position, concrete is poured to form a guide wall to achieve control and positioning of the jacking direction. Finally, reinforced concrete is poured on the opposite side of the jacking direction to form a reaction wall. The wall surface of the reaction wall is perpendicular to the tunnel jacking axis.

[0007] Optionally, in step (2), left and right guide rails are arranged at the bottom of the starting well parallel to the direction of the reaction wall, and a jacking machine worktable that can move back and forth along the left and right guide rails is arranged on the left and right guide rails. The jacking machine worktable can extend and retract up and down; then, worktable guide rails are arranged on the jacking machine worktable along the jacking direction, and the jacking machine is placed on the worktable guide rails.

[0008] Optionally, step (3) specifically includes the following steps: (3.1) Before jacking, establish a ground control network in the starting shaft and jacking direction, use a laser theodolite to determine the jacking axis, ensure the accurate installation position of the pipe jacking machine, and control the initial jacking attitude and axis deviation; (3.2) The jacking machine head is equipped with a mud inlet and discharge pipe. The mud inlet and discharge pipe is used to discharge the excavated soil and also serves as the channel for transmitting the jacking force of the main jacking cylinder. During the jacking process, the main jacking cylinder pushes the jacking machine head into the soil through the mud inlet and discharge pipe along the workbench guide rail to realize the front-end tunneling. (3.3) After the jacking machine head completes the first section of jacking, the main jacking cylinder is reset and the first section of steel pipe is hoisted. Then, the new sludge discharge pipe is connected to the original sludge discharge pipe at the tail of the steel pipe using clamps. After the first section of steel pipe is jacked, the process of hoisting, connecting and jacking the steel pipe is repeated until a high-strength obstacle is encountered. During the jacking process, an axis measurement is performed for each section of steel pipe jacked, and the jacking direction is corrected in real time.

[0009] Optionally, in step (4), the cutter head of the pipe jacking machine is equipped with retractable cutter teeth. When encountering high-strength obstacles, the cutter teeth are retracted to make the outer diameter of the pipe jacking machine smaller than the tool pipe at the front end, and the pipe jacking machine is dragged back to the starting shaft from the steel pipe at the rear. The dragging operation is the opposite of the jacking operation. The pipe jacking machine head is pulled back through the mud inlet and outlet pipes. After pulling back one section of pipe, the mud inlet and outlet pipes are removed and the pulling back continues until the pipe jacking machine exits the pipe to form a clearing space.

[0010] Optionally, the drag-reducing support device in step (5) includes a circular flange connected to the drill pipe at both ends, a support segment symmetrically arranged on the circular flange, and a rotatable radial roller located between adjacent support segments.

[0011] Optionally, the support tube is a hexagonal snowflake-shaped tube, and each radial roller is connected to each corner of the hexagonal snowflake-shaped tube by bolts.

[0012] Optionally, in step (5), the bottom plate is provided with ribs to improve the shell's resistance to bending and torsional deformation.

[0013] Optionally, in step (5), the outer shell is a hollow tube structure, and the radius of the outer shell is smaller than the working radius of the retractable pipe jacking machine.

[0014] Optionally, in step (5), a water injection device is connected to the water injection hole and a pressurization device is connected to the pressurization hole.

[0015] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: The construction method of this invention can cut high-strength obstacles with alloy cutters and remove them completely, requiring only simple manual hole enlargement afterward. The working environment is significantly better than that of manual demolition, greatly reducing safety risks. The obstacle removal method proposed in this invention is a forward obstacle removal method based on the original jacking route, unlike reverse obstacle removal, which requires resetting the receiving well as the starting well for obstacle removal. This invention has lower requirements for cutter configuration; it only needs to distribute alloy cutter heads evenly around the perimeter of the outer shell according to the principle of "dense arrangement for more cuts, sparse arrangement for fewer cuts," based on the size and strength of the obstacle, without the need to consider different cutter heads as with a full-section cutter head. The invention employs various cutting tool combinations to avoid the dangerous situation caused by insufficient cutting capacity when using a cutterhead for obstacle clearing. It achieves different cutting and jacking distances through drill rod connections to clear obstacles of varying lengths. The invention incorporates a drag-reducing support device, using radial pulleys to convert friction during the jacking process into sliding friction, effectively reducing friction and driving torque loss. This allows the power system to be used more efficiently for rotating and cutting obstacles, significantly saving energy. Furthermore, by transforming the ultra-long stroke jacking from a single simply supported beam structure to a multi-segment simply supported beam structure, the invention effectively disperses the sagging and bending caused by the drill rod's own weight and jacking resistance, greatly improving the straightness and accuracy of the jacking trajectory and reducing construction deviations. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the construction process of the present invention. Figure 2 This is a flowchart of the pipe jacking machine's advance and retraction in this invention; Figure 3 This is a flowchart of the obstacle clearing device retraction process in this invention; Figure 4 This is a schematic diagram of the obstacle clearing device in this invention; Figure 5 This is a schematic diagram of the longitudinal section of the retractable jacking pipe in this invention; Figure 6 This is a diagram showing the arrangement of the ribs in this invention; Figure 7 This is a diagram showing the arrangement of the nozzles in this invention; Figure 8 This is a schematic diagram of the drag-reducing support device in this invention. Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0018] like Figure 1 , Figure 2 and Figure 3As shown, the present invention provides a construction method for using a retractable pipe jacking machine to break through high-strength obstacles, comprising the following steps: (1) Excavate the foundation pit and implement structural reinforcement measures for the launching shaft, namely, set up steel supports on the inner side of the pit wall and pour the structural base plate to form the launching shaft of the pipe jacking machine; after the launching shaft is completed, construct guide walls in the jacking direction and construct reaction walls on the corresponding side.

[0019] First, pre-grouting is used to reinforce the soil around the retaining piles to improve ground stability. Before pouring the guide wall and reaction wall, construction surveying should be conducted. Based on the launching shaft and jacking direction, a laser theodolite is used to determine the required axis for the jacking operation to ensure the accuracy of the jacking route. Then, laser theodolite measurements are performed based on the launching shaft and the pipe jacking direction to determine the jacking axis and center position. Based on the measurement results, a 2m long guide pipe is pre-embedded in the pipe jacking direction to control and position the jacking direction. After verifying the position, concrete is poured to form a guide wall approximately 1m thick, achieving control and positioning of the jacking direction. Finally, reinforced concrete is poured on the opposite side of the jacking direction to form reaction wall 9. The surface of reaction wall 9 is perpendicular to the tunnel jacking axis and also perpendicular to the ground of the launching shaft, used to bear the jacking reaction force.

[0020] (2) A pipe jacking machine workbench that can move left, right, up and down is arranged at the bottom of the starting well, and a pipe jacking machine that can retract is arranged on the pipe jacking machine workbench.

[0021] like Figure 5 As shown, left and right guide rails are arranged parallel to the reaction wall at the bottom of the starting shaft. A pipe jacking machine worktable 10 that can move back and forth along the left and right guide rails is arranged on the left and right guide rails. The pipe jacking machine worktable 10 can extend and retract vertically to facilitate the subsequent construction of the arched pipe curtain. Then, worktable guide rails are arranged on the pipe jacking machine worktable along the jacking direction, and the pipe jacking machine 11 is placed on the worktable guide rails.

[0022] After installing the retractable pipe jacking machine, the casing is installed, and construction surveying is conducted again. Construction surveying includes elevation measurement, axis measurement, and leveling. The traverse method can be used to determine the positioning of the pipe jacking machine's drill bit, and control points are set on the working shaft. During pipe jacking, a light target is set at the center of the jacking head, and the jacking head's orientation is determined based on the readings from the light target. A laser theodolite is used to measure the axis of the pipe jacking. If the deviation of the pipe jacking axis exceeds 3mm, it should be corrected promptly. The pipe jacking machine is equipped with adjusting cylinders, which can finely adjust the cutterhead up, down, left, and right to achieve deviation correction and ensure jacking accuracy. For leveling, a second-order leveling route is laid out to transfer the elevation to the vicinity of the starting shaft, and construction elevation control points are established. Leveling is conducted using an NA2 type micrometer with a parallel glass plate and a steel tape for forward and backward observations to ensure elevation control accuracy. With sufficient jacking force, a hydraulic press with a chain can be used to retract the pipe jacking machine in one go, shortening the construction period.

[0023] (3) Check the installation position of the pipe jacking machine. During the jacking process, the main jacking cylinder 13 pushes the head of the pipe jacking machine into the soil through the mud inlet and outlet pipe 12 along the jacking direction to realize the front section excavation; reset the position of the main jacking cylinder and hoist the first section of steel pipe. After the first section of steel pipe is jacked, repeat the steel pipe jacking process until the reinforced concrete pile obstacle is encountered. (3.1) Before jacking, establish a ground control network in the starting shaft and jacking direction, use a laser theodolite to determine the jacking axis, ensure the accurate installation position of the pipe jacking machine, and control the initial jacking attitude and axis deviation; (3.2) The jacking machine head of the pipe jacking machine 11 is equipped with a mud inlet and discharge pipe 12. The mud inlet and discharge pipe 12 is used for both discharging and transporting excavated soil and as a channel for transmitting the jacking force of the main jacking cylinder 13. During the jacking process, the main jacking cylinder 13 pushes the jacking machine head into the soil along the workbench guide rail through the mud inlet and discharge pipe 12 to realize the front-end tunneling. (3.3) After the jacking machine head completes the first section of jacking, the main jacking cylinder is reset and the first section of steel pipe is hoisted. Then, the new sludge discharge pipe is connected to the original sludge discharge pipe by clamps on the lower side of the steel pipe to maintain the continuity of the sludge discharge force transmission system. After the first section of steel pipe is jacked, the process of hoisting, connecting and jacking the steel pipe is repeated until the reinforced concrete pile 14 obstacle is encountered. During the jacking process, the axis measurement is carried out once after each section of steel pipe is jacked, and real-time correction is performed to ensure the control of tunneling accuracy. (4) The pipe jacking machine retracts its cutting teeth so that the outer diameter of the pipe jacking machine is smaller than the outermost tool pipe. The pipe jacking machine then retracts to the starting well to create clearance space. The cutterhead of the pipe jacking machine is equipped with retractable cutter teeth. When encountering high-strength obstacles such as reinforced concrete piles 14, the cutter teeth are retracted to make the outer diameter of the pipe jacking machine smaller than the tool pipe at the front end. The pipe jacking machine is then dragged back to the starting shaft from the steel pipe at the rear. The dragging operation is the opposite of the jacking operation. The pipe jacking machine head is pulled back through the mud inlet and outlet pipes. After each pipe section is pulled back for a length of 6m, the pipe section is removed and the pulling back continues until the pipe jacking machine exits the pipeline and creates clearing space. (5) Carry out obstacle removal preparation work and install the obstacle removal device on the worktable guide rail of the pipe jacking machine;

[0024] like Figure 4 , Figure 6 and Figure 7As shown, a clearing device is installed. The clearing device includes a power system connected to the main jacking cylinder, a drill rod 7 connected to the output shaft of the power system, a drag-reducing support device 8 that passes through the drill rod and is used to stabilize the jacking posture, and a clearing shell fixed to the front end of the drill rod. The clearing shell includes an outer shell 1, alloy cutter heads 2 evenly distributed around the front end of the outer shell, a partition 6 inside the outer shell, a nozzle 3 on the partition with the spray direction facing the alloy cutter heads, and a base plate 4 at the rear end of the outer shell and fixed to the front end of the drill rod. The partition 6, the outer shell 1, and the base plate 4 form a cavity for storing water. The outer shell corresponding to the cavity is provided with a water injection hole and a pressurization hole. The base plate is provided with a rib 5 to improve the bending and torsional deformation resistance of the outer shell. A pressurization device is externally connected to the pressurization hole, and a water injection device is externally connected to the water injection hole.

[0025] The power system is used to drive the obstacle clearing device to rotate and advance forward. The drill rod is a long rod welded from multiple pipe sections. Each pipe section is 6m long. Different pipe lengths can be used depending on different working conditions. According to the actual working conditions and the length of obstacles to be cleared, different numbers of pipes are bolted to the target length of the drill rod. The front section of the first section of the drill rod is bolted to the reserved hole on the base plate, and the ends of the adjacent pipes of the drill rod are connected to the reserved connection holes of the support and drag reduction device.

[0026] The basic structure of the outer shell is a hollow tube structure cast from steel. The radius of the outer shell is smaller than the working radius of the retractable pipe jacking machine. The nozzle is used to spray high-pressure water to the front high-strength alloy cutter head to reduce the wear on the cutter head. The nozzle is arranged at an angle to the outside of the pipe to effectively spray water to the alloy cutter head.

[0027] like Figure 8 As shown, the drag-reducing support device 8 includes circular flanges 804 connected to the drill pipe at both ends, support segments 802 symmetrically arranged on the circular flanges, and rotatable radial rollers 801 located between adjacent support segments. The radial rollers 801 are connected to the support segments 802 by bolts 803. The support segments 802 are hexagonal snowflake-shaped segments. The radial rollers, connected to the hexagonal snowflake-shaped segments by bolts, reduce frictional resistance and improve torque utilization. The hexagonal snowflake-shaped segments reduce deformation such as drill pipe sagging and bending caused by the drill pipe's own weight and jacking resistance, ensuring stable jacking posture.

[0028] Based on the predicted obstacle size, prepare different numbers of drill pipes according to the actual working conditions. Ensure the length of the drill pipe to the obstacle removal target meets the removal requirements. Determine the number of alloy cutter heads to be installed, and arrange a drag-reducing support device at equal intervals along the drill pipe direction. The length can be 3-6 meters depending on the actual working conditions. The drag-reducing support device transforms the long jacking system from a single simply supported beam structure to a multi-segment simply supported beam structure, effectively dispersing the sagging and bending caused by the drill pipe's own weight and jacking resistance, improving the accuracy of the jacking trajectory, and reducing construction deviations. Simultaneously, it reduces torque loss caused by jacking friction. The radius of the obstacle removal device is slightly smaller than the radius of the jacking pipe section. After removing the obstacle, simple hole enlargement is performed to meet the jacking requirements.

[0029] (6) A laser-controlled guidance system is used to ensure the accuracy of the jacking direction before the jacking operation begins. During the jacking operation, the main jacking cylinder pushes the jacking device forward while the power system connects to the drill rod to rotate the outer shell. The alloy cutter on the outer shell cuts the obstacle as a whole under rotation and then wraps the obstacle inside the outer shell. Each jacking is 6m. After one jacking is completed, the main jacking cylinder and power system are restored and the next 6m long drill rod is bolted on. At the same time, a drag reduction support device is arranged to carry out the next jacking operation. During the jacking process, high-pressure water is used to rinse and cool the alloy cutter to reduce the wear on the cutter and improve the cutting efficiency. (7) The outer shell of the obstacle removal device wraps the obstacle and drags the entire outer shell along with the obstacle back to the starting well from the rear steel pipe to remove the obstacle. The dragging operation is the opposite of the jacking operation. Every 6m back, the retracted drill rod is removed until the outer shell and the obstacle are dragged out together. (8) After the obstacle is cleared, the pipe jacking machine continues to jacking, repeating step (3). If an obstacle is encountered again, repeat steps (4) to (7). After the obstacle is cleared, the pipe jacking machine continues to jacking until the entire jacking work is completed.

[0030] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. All components not explicitly stated in this embodiment can be implemented using existing technology.

Claims

1. A construction method for using a retractable pipe jacking machine to break through high-strength obstacles, characterized in that, Includes the following steps: (1) Excavate the foundation pit, implement reinforcement measures in the foundation pit, and pour the structural base slab to form the launching well; then carry out guide wall construction in the jacking direction and reaction wall construction on the corresponding side; (2) A pipe jacking machine workbench that can move left, right, up and down is arranged at the bottom of the starting well, and a pipe jacking machine that can retract is arranged on the pipe jacking machine workbench. (3) During the jacking process, the main jacking cylinder pushes the jacking machine head into the soil through the mud inlet and outlet pipes along the jacking direction; reset the main jacking cylinder, hoist the first section of steel pipe, and repeat the steel pipe jacking process after jacking the first section of steel pipe until a high-strength obstacle is encountered; (4) The pipe jacking machine retracts its cutting teeth so that the outer diameter of the pipe jacking machine is smaller than the tool pipe at the front end. The pipe jacking machine then retracts to the starting well, creating a clearing space. (5) Install a clearing device. The clearing device includes a power system connected to the main jacking cylinder, a drill rod connected to the output shaft of the power system, a drag-reducing support device that passes through the drill rod and is used to stabilize the jacking posture, and a clearing shell fixed to the front end of the drill rod. The clearing shell includes an outer shell, alloy cutter heads that are evenly distributed around the front end of the outer shell, a partition plate inside the outer shell, a nozzle on the partition plate that sprays towards the alloy cutter heads, and a bottom plate at the rear end of the outer shell that is fixed to the front end of the drill rod. The partition plate, the outer shell and the bottom plate form a cavity for storing water. A water injection hole and a pressurization hole are provided on the outer shell corresponding to the cavity. (6) During the obstacle clearing operation, the main jacking cylinder pushes the obstacle clearing device forward, and at the same time, the power system connects to the drill rod to drive the outer shell to rotate. The alloy cutter on the outer shell cuts the obstacle as a whole and then wraps the obstacle inside the outer shell. After one jacking is completed, the main jacking cylinder and power system are restored, and the next section of drill rod is bolted on. At the same time, a drag reduction support device is arranged to carry out the next jacking obstacle clearing operation. During the obstacle clearing process, high-pressure water is used to rinse and cool the alloy cutter. (7) The outer shell of the obstacle removal device wraps the obstacle and drags the entire outer shell along with the obstacle back to the starting well from the rear steel pipe to remove the obstacle. The dragging operation is the opposite of the jacking operation. Each time the drill rod is retracted, it is removed until the outer shell and the obstacle are dragged out together. (8) After the obstacle is cleared, the pipe jacking machine continues to jacking, repeating step (3). If an obstacle is encountered again, repeat steps (4) to (7) until the entire jacking operation is completed.

2. The construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, In step (1), the soil around the retaining piles is first reinforced by pre-grouting. Then, laser theodolite measurements are taken based on the starting shaft and the direction of the pipe curtain jacking to determine the jacking axis and center position. According to the measurement results, guide pipes are pre-embedded in the direction of the pipe curtain jacking. After the position is checked, concrete is poured to form a guide wall to achieve control and positioning of the jacking direction. Finally, reinforced concrete is poured on the opposite side of the jacking direction to form a reaction wall. The wall surface of the reaction wall is perpendicular to the tunnel jacking axis.

3. The construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, In step (2), left and right guide rails are arranged at the bottom of the starting well parallel to the direction of the reaction wall. A pipe jacking machine worktable that can move back and forth along the left and right guide rails is arranged on the left and right guide rails. The pipe jacking machine worktable can extend and retract up and down. Then, worktable guide rails are arranged on the pipe jacking machine worktable along the jacking direction, and the pipe jacking machine is placed on the worktable guide rails.

4. The construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, Step (3) specifically includes the following steps: (3.1) Before jacking, establish a ground control network in the starting shaft and jacking direction, use a laser theodolite to determine the jacking axis, ensure the accurate installation position of the pipe jacking machine, and control the initial jacking attitude and axis deviation; (3.2) The jacking machine head is equipped with a mud inlet and discharge pipe. The mud inlet and discharge pipe is used to discharge the excavated soil and also serves as the channel for transmitting the jacking force of the main jacking cylinder. During the jacking process, the main jacking cylinder pushes the jacking machine head into the soil through the mud inlet and discharge pipe along the workbench guide rail to realize the front-end tunneling. (3.3) After the jacking machine head completes the first section of jacking, the main jacking cylinder is reset and the first section of steel pipe is hoisted. Then, the new sludge discharge pipe is connected to the original sludge discharge pipe by clamps on the lower side of the steel pipe. After the first section of steel pipe is jacked, the process of hoisting, connecting and jacking the steel pipe is repeated until a high-strength obstacle is encountered. During the jacking process, an axis measurement is performed for each section of steel pipe jacked, and the jacking direction is corrected in real time.

5. The construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, In step (4), the cutter head of the pipe jacking machine is equipped with retractable cutter teeth. When encountering high-strength obstacles, the cutter teeth are retracted to make the outer diameter of the pipe jacking machine smaller than the tool pipe at the front end, and the pipe jacking machine is dragged back to the starting well from the steel pipe at the rear. The dragging operation is the opposite of the jacking operation. The pipe jacking machine head is pulled back through the mud inlet and outlet pipes. After pulling back one pipe section, the mud inlet and outlet pipes that have been dragged out are removed, and the pulling back continues until the pipe jacking machine exits the pipe to form a clearing space.

6. The construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, The drag-reducing support device in step (5) includes a circular flange connected to the drill pipe at both ends, a support segment symmetrically arranged on the circular flange, and a rotatable radial roller located between adjacent support segments.

7. A construction method for breaking through high-strength obstacles using a retractable pipe jacking machine according to claim 6, characterized in that, The support tube is a hexagonal snowflake-shaped tube, and each radial roller is connected to each corner of the hexagonal snowflake-shaped tube by bolts.

8. The construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, In step (5), the bottom plate is provided with ribs to improve the shell's resistance to bending and torsional deformation.

9. A construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, In step (5), the outer shell is a hollow tube structure, and the radius of the outer shell is smaller than the working radius of the retractable pipe jacking machine.

10. A construction method for using a retractable pipe jacking machine to break through high-strength obstacles according to claim 1, characterized in that, In step (5), a water injection device is connected to the water injection hole, and a pressurization device is connected to the pressurization hole.

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