A construction method for large-diameter and long-distance pipe jacking in complex geology

Abstract

The invention provides a large-diameter long-distance jacking pipe crossing construction method for complex geology, which relates to the field of jacking pipe construction and comprises the following steps: conducting geological exploration, using a geological drill to drill holes under the surface, the depth of the holes being 20-30m, and the spacing between the holes being 1-10m; arranging control points in a starting well and a receiving well, the control points being arranged on a theoretical jacking axis to provide a reference for subsequent laser measurement, and setting up a laser theodolite to ensure that the height of the laser point matches the height of the pipeline axis, and the direction of the laser point coincides with the central axis of the pipeline; the invention has the beneficial effects of: when a large-diameter pipeline is crossed over a long distance, an auxiliary positioning pipe is used to support the pipeline below, so that the bending and deviation generated when the pipeline is crossed over a long distance in the soil body can be effectively reduced, and when a large-diameter jacking machine is performing jacking operation in the soil body, the auxiliary positioning pipe plays the role of an auxiliary guide for the large-diameter jacking machine, thereby achieving the effect of reducing the deviation.

Description

Technical Field

[0001] The invention relates to the field of pipe jacking construction, in particular to a method for pipe jacking crossing construction with a large diameter and a long distance in complex geology. Background Art

[0002] Pipe jacking construction is a trenchless construction method that can achieve pipeline burial without excavation or with less excavation. It overcomes the friction between the pipeline and the surrounding soil by the jacking force generated by the jacking equipment in the working well, and pushes the pipeline into the soil according to the designed slope and direction. Its principle is to use the thrust of the main jacking cylinder and the pipeline room, relay room, etc. to push the tool pipe or tunneling machine from the working well through the soil layer to the receiving well. It can be used in complex geological or large-diameter pipeline construction operations. Now, a complex geological large-diameter long-distance jacking construction method with a publication number of CN115559734A has been retrieved, including data measurement, including ground control measurement and jacking measurement of the pipe jacking machine. The ground control measurement includes before the pipe jacking construction, according to the provided engineering positioning and measurement standards The given guide wire points, leveling points and other control points are re-measured based on the log data; at the same time, the encrypted control points used in the construction process are measured, and the measurement results are reported to the supervision engineer and the owner for review and approval; the jacking measurement of the pipe jacking machine includes a jacking posture measurement and control system installed on the jacking pipe. The jacking posture measurement and control system includes a light target sensor and a data processing system that receive the laser beam. The vertical and horizontal displacements of the measuring plate of the cutting cabin of the pipe jacking machine with the laser guide point as the reference, the laser incident horizontal angle, and the elevation and rolling angles of the cutting cabin of the pipe jacking machine are measured. The measurement data is manually processed and calculated through long-distance camera monitoring and a microcomputer system, and the position deviation of the pipe jacking machine reflected by the processing results is displayed on the screen of the operating room to guide the operator to correct the deviation of the pipe jacking machine.

[0003] However, in the above technology, the prefabricated pipe section is inserted into the jacking casing at one time, and connected to the original line pipeline with a bent pipe to complete the pipeline crossing installation. However, this method cannot be used for large-diameter and long-distance pipeline crossing, which is prone to pipeline bending and even displacement. Summary of the invention

[0004] The problem to be solved by the present invention is to prevent a large-diameter pipeline from bending or shifting when the pipeline travels a long distance.

[0005] To achieve the above object, the technical solution adopted by the present invention is a large-diameter and long-distance pipe jacking construction method for complex geological conditions, comprising the following steps:

[0006] a. Conduct geological exploration, use geological drilling rigs to drill holes under the surface, the depth of the holes is 20-30m, and the spacing between holes is 1-10m;

[0007] b. Establish the launching well and receiving well, arrange control points in the launching well and receiving well, these control points will be arranged on the theoretical jacking axis to provide a reference for subsequent laser measurement, and set up a laser theodolite to ensure that the height of the laser point matches the height of the pipeline axis, and the direction of the laser point coincides with the central axis of the pipeline;

[0008] c. Set up and calibrate the total station, then select at least two control points with known coordinates at the construction site to place prisms, use the total station to observe the two control points, obtain their three-dimensional coordinates, and perform backsight orientation to ensure that the azimuth of the total station is correct, determine the exact location of the large-diameter pipe jacking machine drilling according to the design drawings or construction plan, and calculate its three-dimensional coordinates, then aim the telescope of the total station at the location, and use the prism to set up obvious markers at the location, after completing the marking of the large-diameter pipe jacking machine drilling position, mark two auxiliary positioning tube drilling positions on both sides below the large-diameter pipe jacking machine drilling position, the drilling positions of the two auxiliary positioning tubes are located below the large-diameter pipe jacking machine drilling position, and are aligned with the large-diameter pipe jacking machine drilling position, check and review each position to ensure the accuracy and reliability of the marking;

[0009] d. Lay the positioning track corresponding to the drilling positions of the two auxiliary positioning tubes in the starting well, ensure that the longitudinal slope of the positioning track is consistent with the designed slope, and the accuracy of the positioning track must meet the requirements, and the allowable deviation is: axis 3mm, top surface elevation 0~+3mm, and the spacing between the two tracks is ±2mm;

[0010] e. Install a small-sized pipe jacking machine on the positioning track and set up a reaction force dispersion frame and a propulsion jack, and start the small-sized pipe jacking machine and the propulsion jack to cooperate with the auxiliary positioning pipe to carry out the jacking operation;

[0011] f. Inject thixotropic mud, and increase the injection volume of thixotropic mud by 50% to ensure sufficient mud protection, reduce the resistance of jacking, strengthen the combination of soil layer and pipe body, and strengthen the support of jacking pipe;

[0012] g. Use a laser theodolite to measure the position and offset of the small-size pipe jacking machine in real time. The laser theodolite will directly measure the position of the measuring light target at the tail of the machine head, and regularly measure the settlement and displacement based on the actual status of the computer head according to the inclinometer inside the machine head. The laser measuring equipment will continuously monitor to ensure that the small-size pipe jacking machine moves along the predetermined path, and take corrective measures in time if deviation is found;

[0013] h. Set up a relay room on the auxiliary positioning pipe. Push the pipe forward in sequence through the relay room until the cylinder stroke is in place. Then, the main jacking cylinder of the main jacking workstation pushes the last interval pipe. Repeat the telescopic jacking process until the auxiliary positioning pipe is pushed from the starting well to the receiving well. After the auxiliary positioning pipe is completed, remove the small-size jacking machine, positioning track, reaction force dispersion frame and pushing jack, and remove the relay room;

[0014] i. Build a heightened workbench in the launch well. The heightened workbench is located below the drilling position of the large-diameter pipe jacking machine, and a guide rail is laid on the heightened workbench. The height of the heightened workbench is adjusted to ensure that the guide rail matches the designed height of the pipeline;

[0015] j. Install and debug the hydraulic jack according to the design requirements, and install sealing rings at the joints of large-diameter pipe joints for sealing;

[0016] k. Start the hydraulic jack, slowly push the large-diameter pipe jacking machine and the large-diameter pipe section into the soil, and constantly control the direction of the large-diameter pipe jacking machine during the pushing process to ensure that the pipeline composed of the large-diameter pipe section is located above the auxiliary positioning pipe after entering the soil, so that the auxiliary positioning pipe supports the pipeline, and the angle between the supporting point of the two auxiliary positioning pipes on the pipeline and the horizontal plane is between 30-45 degrees, and the pipeline is supported by the auxiliary positioning pipe;

[0017] l. Repeat the above jacking steps to make the pipeline pass from the starting well to the receiving well. After completing the pipeline crossing construction, remove the corresponding equipment and perform backfilling.

[0018] Preferably, the auxiliary positioning tube is made of a stainless steel solid tube, and the auxiliary positioning tubes are connected by TIG welding.

[0019] Compared with the prior art, the beneficial effects of the present invention are: by increasing the injection volume of thixotropic mud by 50% to ensure sufficient mud protection, the resistance to jacking can be effectively reduced, the combination of the soil layer and the pipe body can be strengthened, and when a large-diameter pipe passes through a long distance, the auxiliary positioning pipe is used to support the bottom of the pipe, so the bending and deviation of the pipe when it passes through the soil for a long distance can be effectively reduced. When a large-diameter pipe jacking machine performs jacking operations in the soil, the auxiliary positioning pipe acts as an auxiliary guide for the large-diameter pipe jacking machine, thereby achieving the effect of reducing deviation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the drilling position of the pipe jacking machine of the present invention;

[0021] Figure 2 It is a schematic diagram of the pipeline structure of the present invention;

[0022] Among them, 1-the drilling position of the large-diameter pipe jacking machine, 2-the drilling position of the small-size pipe jacking machine, 3-the large-diameter pipe section, and 4-the auxiliary positioning pipe. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "back" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0025] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be an electrical connection; it can be a hydraulic oil circuit connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] See also Figure 1-Figure 2 As shown, a large-diameter and long-distance jacking pipe crossing construction method for complex geology, the diameter of the large-diameter pipeline is between 2m-20m, geological exploration is carried out at the location required for construction, and a geological drill is used to drill holes under the surface. Due to the complex geology, the depth of the borehole is 20-30m, and the specific depth needs to be adjusted according to the on-site construction conditions. Due to the complex geology, the borehole spacing should be shortened from 10-20m to 1-10m, and the specific changes are made according to the complexity of the on-site soil. After the geological exploration is completed, the construction sites of the starting well and the receiving well are selected and determined through measurement. The locations of the starting well and the receiving well should be set in an open area as much as possible without occupying the position of the integrated pipeline. The starting well and the receiving well are excavated and established after the starting and end points of the construction are determined, and a reaction wall is constructed in the receiving well.

[0027] Control points are arranged in the starting well and the receiving well. These control points will be arranged on the theoretical jacking axis to provide a reference for subsequent laser measurement. A laser theodolite is set up to ensure that the height of the laser point matches the height of the pipeline axis and that the direction of the laser point coincides with the centerline of the pipeline. Starting from the positioning of the pipeline axis, the coordinates of each part and the layout data are calculated in advance through the polar coordinate measurement method.

[0028] Then, the total station is used to measure and mark the drilling position 1 of the large-diameter pipe jacking machine. First, the relevant parameters of the total station, such as angle measurement accuracy, distance measurement accuracy, etc., are checked and calibrated to ensure that they are within the normal working range. Then, the accessories required for the total station, such as tripod, prism, communication cable, etc., are prepared. The tripod is installed at the measuring station position to ensure that the tripod is stable and placed on the horizontal ground. The total station is fixed on the tripod and centered and leveled with the centering device and leveling screw to ensure that the vertical axis of the total station is perpendicular to the ground. The total station is turned on, and at least two control points with known coordinates are selected at the project site to place the prism. The total station is used to align these control points. Observe the two control points, obtain their three-dimensional coordinates, and perform backsight orientation to ensure that the azimuth of the total station is correct. Determine the exact position of the large-diameter pipe jacking machine drilling according to the design drawings or construction plans, and calculate its three-dimensional coordinates. Then aim the telescope of the total station at that position, and use a prism or other auxiliary equipment to set up obvious markers at that position, such as spray paint, signboards, etc. After completing the marking of the large-diameter pipe jacking machine drilling position 1, check and review each position to ensure the accuracy and reliability of the marking. Other measuring equipment, such as levels, theodolites, etc., can also be used to cross-verify the marked positions.

[0029] After checking and verifying that the large-diameter pipe jacking machine drilling position 1 is marked correctly, use the total station to repeat the above measurement steps, and mark two small-sized pipe jacking machine drilling positions 2 on both sides below the large-diameter pipe jacking machine drilling position 1. The two small-sized pipe jacking machine drilling positions 2 are located below the large-diameter pipe jacking machine drilling position 1 and fit together with the large-diameter pipe jacking machine drilling position 1, so that the small-sized pipe jacking machine drilling position 2 can support the large-diameter pipe jacking machine drilling position 1, wherein the angle between the support point and the horizontal plane is between 30-45 degrees. After checking and verifying the two small-sized pipe jacking machine drilling position 2 marks to ensure that they are correct, lay positioning tracks corresponding to the two small-sized pipe jacking machine drilling positions 2 in the starting well. The accuracy of the positioning track must meet the requirements, and the allowable deviation is: axis 3mm, top surface elevation 0~+3mm, and spacing between the two tracks is ±2mm.

[0030] After the positioning track is laid, two small-sized pipe jacking machines are set on the positioning track. The model of the pipe jacking machine can be EBZ160 pipe jacking drilling rig. The length of this pipe jacking machine is 10100mm, the body height is 1800mm, the outer width of the crawler is 600mm, the body width is 2900mm, the total power is 260KW, the cutting motor power is 160KW, the power supply voltage is 1140V, and the grounding pressure is 0.14MPa. This model of pipe jacking machine can adapt to the minimum direct pipe size of about 1.6 meters, that is, this model of pipe jacking machine can adapt to the auxiliary positioning pipe with a minimum diameter of 1.6 meters 4. The specific specifications of the small-sized pipe jacking machine also need to be determined according to the specific construction conditions.

[0031] The auxiliary positioning tubes 4 are connected by TIG welding or socket connection. The auxiliary positioning tube 4 is made of stainless steel. The auxiliary positioning tube 4 can be a solid tube made of stainless steel. Its high strength and corrosion resistance, its material and TIG welding process can effectively reduce the bending after long-distance splicing, and it has excellent load-bearing capacity. If the required diameter of the auxiliary positioning tube 4 is too large, the auxiliary positioning tube 4 can also be set as a stainless steel hollow tube, and the interior of the stainless steel hollow tube is filled with hard polyurethane foam. This material has high density and good sealing after filling, can provide good support, and reduce pipeline deformation caused by voids in the tube. Which material of the auxiliary positioning tube 4 to use during the construction process needs to be determined according to specific needs.

[0032] Two small-sized pipe jacking machines are installed on corresponding positioning tracks, and reaction force dispersion frames and thrust jacks are respectively set according to the positions and sizes of the small-sized pipe jacking machines. The thrust jack is started to apply thrust to the small-sized pipe jacking machine so that the small-sized pipe jacking machine enters the soil. The thrust jack is then controlled to retract. An auxiliary positioning pipe 4 is installed between the thrust jack and the small-sized pipe jacking machine. The thrust jack is then used to push the small-sized pipe jacking machine into the soil for a distance. The thrust jack is then retracted again. Another auxiliary positioning pipe 4 is installed between the auxiliary positioning pipe 4 and the thrust jack. The two auxiliary positioning pipes 4 are connected by TIG welding process. The thrust jack is then started again. The above operation is repeated to implement the jacking operation.

[0033] At the same time, thixotropic mud is injected, and the injection amount of thixotropic mud is increased by 50% to ensure sufficient mud protection, effectively reduce the resistance of jacking, strengthen the combination of soil layer and pipe body, and reinforce the jacking support. During the jacking process of small-size pipe jacking machine, when the pressure P of its soil bin is less than the active soil pressure Pa of the soil layer where the small-size pipe jacking machine is located, that is, P<Pa, the ground will settle; on the contrary, if the pressure P of the soil bin is greater than the passive soil pressure Pp of the soil layer where the small-size pipe jacking machine is located, that is, P>Pp, the ground will bulge; therefore, the soil bin pressure can only be controlled between Pa<P<Pp to achieve soil pressure balance, so as not to have a major impact on the ground, thereby meeting the requirements for ground settlement in pipe jacking construction. During the jacking process, the soil bin pressure is controlled to be Pa<P<Pp.

[0034] After the small-size pipe jacking machine enters the soil, the laser theodolite is used to measure the position and offset of the small-size pipe jacking machine in real time. The laser theodolite will directly measure the position of the measuring light target at the tail of the machine head, and regularly perform settlement and displacement measurements based on the actual status of the computer head calculated by the inclinometer inside the machine head. The laser measuring equipment will continue to monitor to ensure that the small-size pipe jacking machine moves forward along the predetermined path. When the jacking reaches the last 30 to 50 meters, manual measurement may be used to review the entire pipeline to ensure the accuracy of the measurement work, and the position and posture of the small-size pipe jacking machine are analyzed based on the data provided by the theodolite to determine whether there is an offset. If an offset is found, corrective measures are taken in a timely manner, such as adjusting the jacking direction, adding support points, etc.

[0035] When the small pipe jacking machine enters the soil a certain distance, it is necessary to set up a relay room on the auxiliary positioning pipe 4. First, the total thrust F during the jacking process is calculated based on parameters such as the outer diameter of the auxiliary positioning pipe 4, the physical properties of the soil (such as wet weight, static earth pressure coefficient, etc.), and the jacking length.

[0036] Formula reference: F = F1 + F2, where F1 is the head-on resistance and F2 is the jacking resistance.

[0037] The calculation formula of the head-on resistance F1 is: F1 = π / 4 × D² × P, where D is the outer diameter of the pipe and P is the control soil pressure.

[0038] The calculation formula for the jacking resistance F2 is: F2 = πD × f × L, where f is the average comprehensive friction resistance of the outer surface of the pipe, D is the outer diameter of the pipe, and L is the jacking distance.

[0039] Next, the maximum jacking force Fds allowed by the force transmission surface of the steel pipe jacking is calculated to determine the actual available jacking force range.

[0040] Formula reference: Fds = fs × Ap, where fs is the design value of the compressive strength of the steel, and Ap is the minimum effective force transmission area of ​​the pipeline.

[0041] Basis for setting: The number of relay rooms and their positions on the axis of the jacking pipe section should be determined based on the friction calculation between the pipeline and the soil layer. The jacking force used by the equipment should be considered as a reserve force at 70%-80% of the design value of the equipment jacking force.

[0042] Setting time: When the thrust of the main jacking cylinder reaches 40%-60% of the design thrust of the relay room, a first-level relay room should be placed. In the early stage of pipe jacking construction, the trigger condition is relatively low in order to reserve a certain safety margin; thereafter, whenever the thrust of the main jacking cylinder reaches 70%-80% of the design thrust of the relay room, a first-level relay room should be placed. The setting trigger condition of subsequent relay rooms is higher, because after one or more relay rooms have been placed, the existing relay rooms are already sharing the jacking force. Improving the trigger condition is to ensure that subsequent relay rooms have better fixed force sharing capabilities, and to avoid too frequent placement of relay rooms, reduce construction costs, and increase construction efficiency; when the main jacking cylinder reaches 80% of the thrust of the relay cylinder, the relay room should be started.

[0043] After the auxiliary positioning pipe 4 is pushed forward through the relay room in sequence to the cylinder stroke, the main jacking cylinder of the main jacking workstation pushes the last interval pipeline, and the above-mentioned relay room and main jacking cylinder telescopic jacking process is repeated continuously until the auxiliary positioning pipe 4 is jacked from the starting well to the receiving well. After the auxiliary positioning pipe 4 is completed, the small-size jacking machine, positioning rail, reaction force dispersion frame and thrust jack are removed, and the relay room is removed, following the network structure, load size and the principle of small first and large later, to ensure the stability and safety of the dismantling process.

[0044] Subsequently, an elevated workbench is built below the drilling position 1 of the large-diameter pipe jacking machine in the starting well. The height is adjusted by the elevated workbench to ensure that the guide rail matches the design height of the pipeline. Then, the guide rail is laid on the elevated platform. When laying the guide rail, ensure that the longitudinal slope of the guide rail is consistent with the design slope, and the accuracy of the guide rail must meet the requirements. The allowable deviation is: axis 3mm, top surface elevation 0~+3mm, and the spacing between the two rails is ±2mm, to ensure that the large-diameter pipe segment 3 can move forward smoothly during the jacking process. Then, the hydraulic jack is installed and debugged according to the design requirements, and sealing rings are installed at the joints of the large-diameter pipe segments 3 for sealing to prevent leakage during the jacking process. The large-diameter pipe segments 3 are connected by socket connections to form a pipeline.

[0045] Then start the hydraulic jack to slowly push the large-diameter pipe section 3 and the large-diameter pipe jacking machine into the soil, and continuously control the direction of the large-diameter pipe jacking machine during the pushing process to ensure that the pipeline composed of the large-diameter pipe section 3 is located above the auxiliary positioning pipe 4 after entering the soil, so that the auxiliary positioning pipe 4 supports the pipeline, and the angle between the supporting points of the two auxiliary positioning pipes 4 and the horizontal plane is between 30-45 degrees. The pipeline is supported by the auxiliary positioning pipe 4 to avoid bending and deviation caused by the large diameter and long distance during the crossing process. The pipeline is positioned by the auxiliary positioning pipe 4 and the two auxiliary positioning pipes 4 can be regarded as guide rails to assist the pushing direction of the large-diameter pipe jacking machine, which can effectively avoid the deviation of the large-diameter pipe jacking machine when pushing into the soil.

[0046] During the jacking process, a mud jacket is formed around the pipe through the grouting system. The pipe slides in the mud jacket while earth is continuously removed to maintain space in the starting well.

[0047] At the same time, during the jacking process, it is necessary to closely monitor the jacking conditions of the pipeline, such as deviation, jacking, rolling angle and other parameters. Once deviation or abnormality is found, it is necessary to adjust the jacking parameters or take corrective measures in time.

[0048] After the pipeline enters the soil for a certain distance, a relay room is set up according to the above-mentioned setting basis, and the pipeline is pushed forward through the relay room in sequence until the cylinder stroke is in place, and then the main jacking cylinder of the main jacking workstation pushes the last interval pipeline, and the telescopic jacking process is repeated continuously until the pipeline is pushed from the starting well to the receiving well, completing the long-distance crossing construction of large-diameter pipelines, and dismantling and finishing work of related equipment, and finally backfilling the starting well, receiving well and tunnel.

[0049] During the large-diameter pipeline crossing process, since there is an auxiliary positioning pipe 4 under the pipeline for support throughout the whole process, it can effectively reduce the bending and deviation of the pipeline composed of large-diameter pipe sections 3 when crossing the soil over a long distance, and can also play the role of auxiliary guide to reduce deviation when the large-diameter jacking machine performs jacking operations during construction.

[0050] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A large-diameter and long-distance pipe jacking construction method for complex geological conditions, characterized in that: The following steps are involved: a. Conduct geological exploration, use geological drilling rigs to drill holes under the surface, the depth of the holes is 20-30m, and the spacing between holes is 1-10m; b. Establish the launching well and receiving well, arrange control points in the launching well and receiving well, these control points will be arranged on the theoretical jacking axis to provide a reference for subsequent laser measurement, and set up a laser theodolite to ensure that the height of the laser point matches the height of the pipeline axis, and the direction of the laser point coincides with the central axis of the pipeline; c. Set up and calibrate the total station, then select at least two control points with known coordinates at the construction site to place prisms, use the total station to observe the two control points, obtain their three-dimensional coordinates, and perform backsight orientation to ensure that the azimuth of the total station is correct, determine the exact location of the large-diameter pipe jacking machine drilling according to the design drawings or construction plan, and calculate its three-dimensional coordinates, then aim the telescope of the total station at the location, and use the prism to set up obvious markers at the location, after completing the marking of the large-diameter pipe jacking machine drilling position, mark two auxiliary positioning tube drilling positions on both sides below the large-diameter pipe jacking machine drilling position, the drilling positions of the two auxiliary positioning tubes are located below the large-diameter pipe jacking machine drilling position, and are aligned with the large-diameter pipe jacking machine drilling position, check and review each position to ensure the accuracy and reliability of the marking; d. Lay the positioning track corresponding to the drilling positions of the two auxiliary positioning tubes in the starting well, ensure that the longitudinal slope of the positioning track is consistent with the designed slope, and the accuracy of the positioning track must meet the requirements; e. Install a small-sized pipe jacking machine on the positioning track and set up a reaction force dispersion frame and a propulsion jack, and start the small-sized pipe jacking machine and the propulsion jack to cooperate with the auxiliary positioning pipe to carry out the jacking operation; f. Inject thixotropic mud, and increase the injection volume of thixotropic mud by 50% to ensure sufficient mud protection, reduce the resistance of jacking, strengthen the combination of soil layer and pipe body, and strengthen the support of jacking pipe; g. Use a laser theodolite to measure the position and offset of the small-size pipe jacking machine in real time. The laser theodolite will directly measure the position of the measuring light target at the tail of the machine head, and regularly measure the settlement and displacement based on the actual status of the computer head according to the inclinometer inside the machine head. The laser theodolite will continuously monitor to ensure that the small-size pipe jacking machine moves along the predetermined path, and take corrective measures in time if deviation is found; h. Set up a relay room on the auxiliary positioning pipe, and push the auxiliary positioning pipe forward through the relay room in sequence until the cylinder stroke is in place, and then the main jacking cylinder of the main jacking workstation pushes the last interval pipe, and repeats the telescopic jacking process continuously until the auxiliary positioning pipe is pushed from the starting well to the receiving well. After the auxiliary positioning pipe is completed, dismantle the small-size jacking machine, positioning track, reaction force dispersion frame and pushing jack, and dismantle the relay room; i. Build a heightened workbench in the launch well. The heightened workbench is located below the drilling position of the large-diameter pipe jacking machine, and a guide rail is laid on the heightened workbench. The height of the heightened workbench is adjusted to ensure that the guide rail matches the designed height of the pipeline; j. Install and debug the hydraulic jack according to the design requirements, and install sealing rings at the joints of large-diameter pipe joints for sealing; k. Start the hydraulic jack and slowly push the large-diameter pipe jacking machine and large-diameter pipe sections into the soil. During the pushing process, continuously control the direction of the large-diameter pipe jacking machine to ensure that the pipeline composed of large-diameter pipe sections is located above the auxiliary positioning pipes after entering the soil, so that the auxiliary positioning pipes support the pipeline, and the angle between the supporting points of the two auxiliary positioning pipes and the horizontal plane is between 30-45 degrees, and the pipeline is supported by the auxiliary positioning pipes.

2. A large-diameter and long-distance pipe jacking construction method for complex geological conditions according to claim 1, characterized in that: The auxiliary positioning tube is made of a stainless steel solid tube, and the auxiliary positioning tubes are connected by TIG welding.

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