A method for preventing winding and controlling stress uniform distribution of HDPE pipe group synchronous back dragging

Abstract

The present application relates to a kind of construction engineering trenchless technology field, in particular to a kind of HDPE pipe group synchronous back-drawing anti-winding and stress uniform distribution control method;Specifically, in the pipe group back-drawing construction, connecting beam splitter at the rear end of reamer, respectively insert HDPE pipe into the rigid channel corresponding to beam splitter, so that pipe group as a whole system is back-drawing construction, and stress monitoring device is supplemented to carry out HDPE pipe stress monitoring in back-drawing process, respectively control grouting flow by grouting pump system, reasonably reduce the pipe friction in back-drawing process.The present application sets up beam splitter and monitors pipe group stress in the pipe group back-drawing construction, reduces the possibility of winding of each HDPE pipe, makes construction process monitorable, ensures that each pipe is balanced in back-drawing process, reduces single pipe overload risk to minimum, avoids HDPE pipe damage in back-drawing process, overall greatly reduces the winding, pipe jam, breakage and other construction accident rate in HDPE pipe group back-drawing construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pipeline construction, in particular to a method for preventing winding and controlling stress distribution of HDPE pipe group during synchronous back dragging. BACKGROUND

[0002] In municipal power, communication and other pipe network engineering, the non-excavation laying of HDPE pipe by horizontal directional drilling technology is one of the current mainstream processes. The main construction process is to first drill a guide hole by using a horizontal directional drilling machine, then expand the guide hole by using an expander, and finally back drag the HDPE pipe into the formed hole. However, under the construction conditions of long-distance back dragging, curved trajectory of the hole, and soft soil stratum, when multiple HDPE pipes are back dragged in parallel, the pipe group is easily twisted due to the influence of the irregular inner wall of the hole, curved trajectory, and geological flow state, etc., resulting in mutual winding. This not only easily causes scratches on the outer wall of the HDPE pipe, affecting the service life, but also may cause stress concentration at the winding point of the pipe group, leading to the pipe group being stuck in the hole, resulting in back dragging failure.

[0003] In addition, due to the influence of the non-uniformity of hole expansion and the local difference of stratum resistance, the stress distribution of the total pulling force on each HDPE pipe is extremely uneven before back dragging, especially when back dragging to the curved section of the hole, the problem of uneven stress distribution is more prominent. Some HDPE pipes may bear a pulling force far exceeding the average value, which may cause the expander to fail to advance smoothly, resulting in a rough expansion path during back dragging, or even cause some HDPE pipes to be damaged or even broken due to overload.

[0004] The traditional construction method is to weld multiple HDPE pipes into a rigid whole for back dragging. However, in actual construction, on the one hand, the whole pipe group is not conducive to the maintenance and replacement of individual HDPE pipes in the later period, and on the other hand, the whole pipe group lacks flexibility, and it is difficult to adjust the stress distribution of each HDPE pipe, which is not conducive to passing through the curved section of the hole, and the stress concentration problem of individual pipes may be reflected to the whole pipe group, leading to greater risks during back dragging. Therefore, the pipe group can only rely on artificial experience to increase the grouting flow to lubricate the pipe group, which is a rough process and the effect is difficult to ensure. Therefore, it is of great significance to develop a method for effectively preventing the winding of HDPE pipe group during synchronous back dragging and effectively controlling the stress distribution. SUMMARY

[0005] The present application aims to solve the problem that the conventional HDPE pipe group synchronous back-dragging construction method cannot effectively prevent the pipe group from winding and causing pipe damage or jamming, and the stress distribution of the pipe is uneven during back-dragging.

[0006] To solve the above technical problems, the present application provides a kind of HDPE pipe group synchronous back-dragging anti-winding and stress distribution control method, which monitors and manages the back-dragging construction of the pipe group as a whole system by setting a beam splitter and a stress monitoring device on the pipe group, mainly including the following steps:

[0007] Step S1, drilling a guide hole; use horizontal directional drilling to drill a guide hole in the soil layer and develop a reaming scheme;

[0008] Step S2, equipment preparation; select a reamer according to the reaming scheme, and prepare a beam splitter with several rigid channels; the beam splitter is provided with a grouting inlet for connecting a mud delivery pipe; the number of rigid channels is the same as the number of HDPE pipes, and the inner wall is embedded with several high-strength wear-resistant balls, and the edge is provided with several mud injection holes, which are connected to one grouting inlet in one group of rigid channels;

[0009] Step S3, equipment assembly; connect the beam splitter behind the reamer, insert the numbered HDPE pipes to be back-dragged into the rigid channels of the beam splitter, and connect the reamer; connect each group of grouting inlets with one end of the mud delivery pipe, and connect a multi-channel independent control grouting pump system with the other end; the mud delivery pipe is provided with several grouting holes at equal intervals; install a stress monitoring device at the connection part of the HDPE pipe group and the beam splitter; the stress monitoring device is connected to a data acquisition instrument on the ground through a wire; the data acquisition instrument is linked with the grouting pump system;

[0010] Step S4, back-dragging operation and stress monitoring; start the reamer, which pulls the beam splitter and HDPE pipe group forward in the hole; start the grouting pump system to continuously inject mud into the hole; during back-dragging, the stress monitoring device transmits the stress change information of each pipe in the HDPE pipe group to the data acquisition instrument, which compares the stress information of each HDPE pipe and transmits abnormal data to the grouting pump system, which controls the mud injection flow rate of the HDPE pipe with abnormal stress in real time;

[0011] Step S5, back-dragging is completed, the site is cleaned and withdrawn; under the stress monitoring and control of step S4, the HDPE pipe group is back-dragged synchronously and pulled out from the hole exit; after removing the relevant devices and equipment, the site is cleaned up, the topography and environment are restored.

[0012] Further, in step S1, the reaming scheme adopts a hierarchical reaming process, step S1 reaming the hole to the previous level of the final hole size, and in step S3 the last level of the reamer is connected with the beam splitter and the to-be-towed HDPE pipe group.

[0013] Further, in step S3, the mud delivery pipe and the wire are respectively fixed on the outer wall of the HDPE pipe in a spiral winding manner along the axial direction of the HDPE pipe.

[0014] Further, in step S3, the stress monitoring device is a high-precision tension sensor for measuring the absolute tension of each HDPE pipe.

[0015] Further, after the equipment assembly in step S3 is completed, the following tests are also performed:

[0016] Sensor test: drill the reamer into the hole for a short distance, and observe whether the data acquisition instrument normally reads the tension data of each HDPE pipe;

[0017] Grouting test: start the grouting pump system in the control room, control each mud delivery pipe for grouting respectively, confirm whether grout flows out of the grouting holes on the mud delivery pipe and the mud injection holes of the beam splitter, and observe whether the grout flow can be controlled by the grouting pump system;

[0018] Logical simulation: perform a control simulation, manually input the stress increase information of a certain pipe, and observe whether the grouting pump system accurately executes the instruction to increase the grouting amount of the mud delivery pipe corresponding to the certain pipe.

[0019] Further, the beam splitter is a modular unit, and multiple beam splitters can be spliced with each other, and a single beam splitter includes a main body and a rigid channel penetrating through the main body.

[0020] Further, the end of the main body is fixedly provided with a lug plate, and the side wall is fixedly provided with a lug, and the lug plate and the lug are provided with thread holes matched with each other, the lug can be embedded between the lug plates of the main bodies of other beam splitters, and each beam splitter is connected by inserting a screw rod into the thread holes.

[0021] Further, the side wall of the main body is provided with a pipe groove, and the pipe groove is provided with a grouting inlet, and the pipe groove is used to accommodate the mud delivery pipe connected with the grouting inlet.

[0022] Further, in step S3, an adapter is connected between the reamer and the beam splitter, the adapter includes a connecting plate connected with the beam splitter and the HDPE pipe, and a rotating shaft fixed with the connecting plate, the other end of the rotating shaft is connected with the reamer, the inside of the rotating shaft is a bearing structure, and the end of the rotating shaft connected with the reamer can rotate axially.

[0023] Compared with the prior art, the present application has the beneficial effects that:

[0024] In the synchronous back-dragging construction of the HDPE pipe, the introduction of the beam splitter allows each HDPE pipe to be independently limited in the respective rigid channel, avoiding the contact of the HDPE pipes at the source, thereby effectively preventing the direct friction and possible entanglement between the HDPE pipes. And in the back-dragging construction process, the real-time stress of the HDPE pipe is fed back through the stress monitoring device, and then the friction resistance of each HDPE pipe during back-dragging is adjusted by adjusting the mud injection flow, further reducing the possibility of entanglement of the HDPE pipe. The construction process is monitored by the above technical scheme, ensuring that the forces of each pipe during back-dragging are balanced, and the risk of single pipe overload is minimized. The present application greatly reduces the entanglement, pipe jamming, and pipe breakage during the back-dragging construction of the HDPE pipe, ensuring the safety of the long-term operation of the pipe network and reducing the huge economic losses caused by construction failure. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings, which are included to provide a further understanding of the present application and constitute a part of this application, illustrate certain illustrative embodiments of the present application and are used to explain the present application, but do not constitute an improper limitation on the present application.

[0026] Figure 1 is a schematic diagram of the cross section of the synchronous back-dragging construction scene of the first embodiment of the present application HDPE pipe group;

[0027] Figure 2 is a schematic diagram of the overall structure of the beam splitter of the second embodiment of the present application;

[0028] Figure 3 is a schematic diagram of the overall structure of the connection of each component in the present application;

[0029] Figure 4 is a schematic diagram of the adapter structure in the present application.

[0030] In the drawings: 1, HDPE pipe group; 2, beam splitter; 21, main body; 211, tab; 212, lug; 213, threaded hole; 214, mud injection hole; 215, grouting inlet; 216, pipe groove; 22, rigid channel; 221, ball; 3, adapter; 31, connecting plate; 32, rotating shaft; 4, reamer; 5, stress monitoring device. DETAILED DESCRIPTION

[0031] The technical solutions of the present application will be described below in conjunction with the drawings of the present application, but the described embodiments are only a part of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0032] It should be noted that in the description of this invention, terms such as "upper," "lower," "inner," "outer," "front," and "rear," indicating directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings, for example, the drawings... Figure 1 This refers to the placement of each device in the normal working state of the present invention. "Front" refers to the direction of travel during the back-hauling construction, and "rear" is the opposite. This is only for ease of description and is not intended to indicate or imply that the device or component must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in this invention. These drawings are not to scale, and some details may be enlarged or omitted for illustrative purposes.

[0034] like Figure 1 As shown, a specific embodiment of the present invention takes a single-stage back-pull-back project of a pipe group consisting of four HDPE pipes as an example. Specifically, the pipe group needs to be pulled back through holes with high frictional resistance and uneven distribution in various parts. The soft soil inside the holes easily absorbs the HDPE pipes, leading to the initial assessment that pipe entanglement is likely to occur during the back-pull-back construction. Therefore, in this project, a pipe splitter 2 and a stress monitoring device 5 are used to treat the pipe group as a non-rigid whole during the back-pull-back construction, preventing pipe entanglement and monitoring and managing stress during the back-pull-back process. The anti-entanglement and stress distribution control method for synchronous back-pull-back of HDPE pipe groups of the present invention mainly includes the following steps:

[0035] Step S1, drilling the pilot hole;

[0036] The diameter of the single HDPE pipe to be pulled back in this project is set at 160mm. First, a horizontal directional drill is used to drill into the soil to form a 200mm diameter guide hole. Then, a graded hole-expanding process is developed, and the guide hole is expanded into a 650mm diameter hole according to the hole diameters of 350mm--500mm--650mm. The final hole diameter is greater than the equivalent total diameter of HDPE pipe group 1 after being arranged in a non-contact 2×2 matrix. The graded hole-expanding process is beneficial to improving the overall stability of the hole inner wall. In this step, the hole is expanded to the 500mm level.

[0037] Step S2, Equipment preparation;

[0038] According to the reaming scheme, the final-stage reamer 4 is selected, and a splitter 2 with four rigid channels 22 is prepared synchronously, each rigid channel 22 being used to accommodate an HDPE pipe; the inner diameter of the rigid channel 22 on the splitter 2 is slightly larger than the diameter of the HDPE pipe, and the rigid channels 22 are arranged in a 2x2 rectangular pattern, and the inner wall is embedded with a plurality of high-strength wear-resistant balls 221, the length of the splitter 2 is about 1.5 m, and the cross-sectional size is 480 mm x 480 mm; a plurality of mud injection holes 214 are also arranged on the splitter 2 and distributed at the edges of the rigid channels 22, the mud injection holes 214 are grouped as a single rigid channel 22, each group of mud injection holes 214 is connected to a separate grouting inlet 215, and the grouting inlet 215 is used to connect to an external mud delivery pipe.

[0039] The use of the splitter 2 independently limits the front section of each HDPE pipe in the respective rigid channel 22, avoiding contact between the HDPE pipes at the source, thereby preventing the occurrence of entanglement caused by direct friction between the front section HDPE pipes during the back-dragging process of the pipe group.

[0040] During the back-dragging process, the advancement of the HDPE pipe is mainly affected by the pulling force of the reamer 4 and the frictional resistance of the hole wall, and the HDPE pipe itself is a structure with elasticity, which can cause elastic peristalsis of the HDPE pipe due to the action of the pulling force. The balls 221 arranged in the rigid channel 22 can reduce the frictional resistance between the outer wall of the HDPE pipe and the rigid channel 22, allowing the HDPE pipe to move freely in the rigid channel 22, reducing the stress on the HDPE pipe, and preventing damage to the HDPE pipe. In addition, the reamer 4 is excavated by its own rotation, and the rotational torque generated thereby can be transmitted to the HDPE pipe or the splitter 2, causing the HDPE pipe or the splitter 2 to rotate slightly. The arrangement of the balls 221 in the rigid channel 22 allows the HDPE pipe or the splitter 2 to rotate slightly, preventing the rotation of the HDPE pipe or the splitter 2 from affecting each other, causing the HDPE pipe or the splitter 2 to generate mutual resisting torsional forces and be damaged, and the rotation can also improve the passability of the HDPE pipe at certain curved positions in the hole, further reducing the overall resistance during the advancement of the HDPE pipe group 1.

[0041] Step S3, equipment assembly;

[0042] After the final-stage 650 mm reamer 4, the splitter 2 is connected, the four HDPE pipes are numbered and inserted into the rigid channels 22 on the splitter 2, and the reamer 4 is connected; one end of the mud delivery pipe is connected to each group of grouting inlets 215, the mud delivery pipe is tightly fixed on the outer wall of the HDPE pipe in a spiral winding manner along the axis of the HDPE pipe, and a plurality of grouting holes are equally spaced, and the other end of the mud delivery pipe is connected to a multi-channel independent control grouting pump system.

[0043] In the front end of each HDPE pipe, near the part connected with the beam splitter 2, a high-precision tension sensor is installed as a stress monitoring device 5 to measure the absolute tension of each HDPE pipe. The stress monitoring device 5 is connected to the ground data acquisition instrument through wires, which are tightly fixed on the outer wall of the HDPE pipe in a spiral winding manner along the axis direction of the HDPE pipe. The data acquisition instrument is linked with the grouting pump system.

[0044] During the back-dragging process, each HDPE pipe is a flexible body with significant elasticity, bearing the pulling force from the reamer 4. The overall mechanical relationship is basically equivalent to: the total pulling force of the reamer 4 = the tension of the head of the HDPE pipe = the sum of all local frictional resistance from the front section to the rear section of the HDPE pipe.

[0045] Therefore, the control strategy executed by the data acquisition instrument linked with the grouting pump system is: when the stress data of a certain HDPE pipe is significantly greater than the average stress of other HDPE pipes, the mud injection flow rate of the current HDPE pipe should be increased. Specifically, during the HDPE pipe's travel, the soil at different positions in the hole wall will bring different frictional resistance to each HDPE pipe, especially when passing through the curved sections of the hole, the different frictional resistance of the inner and outer curves will also be directly applied to the HDPE pipes at different positions. When a certain HDPE pipe passes through a certain position, the frictional resistance increases, which is reflected in the increase of the tension of the HDPE pipe. Therefore, it is necessary to increase the mud injection flow rate to reduce the frictional resistance between the HDPE pipe and the hole wall, thereby reducing the tension of the HDPE pipe, and overall avoiding the phenomenon of tensile damage caused by uneven stress on the HDPE pipe. In addition, when the middle and rear sections of each HDPE pipe contact each other, the frictional resistance between them will also cause changes in the tension of the HDPE pipes that contact each other. When the mud injection flow rate of the corresponding HDPE pipe is increased, the mud delivery pipe is fixed along the outer wall of the HDPE pipe in a spiral winding manner, and a number of grouting holes are also equally spaced, which will also reduce the frictional resistance between the HDPE pipes, further reducing the risk of mutual entanglement caused by the frictional contact between the HDPE pipes.

[0046] Before formal back-dragging, after the reamer 4, the beam splitter 2 and the HDPE pipe group 1 are connected, the hole mouth should also be debugged to check whether the connection of each component is normal, and the following system tests should be performed:

[0047] Sensor test: drive the reamer 4 into the hole for a short distance, and observe whether the data acquisition instrument normally reads the tension data of each HDPE pipe;

[0048] Grouting test: start the grouting pump system in the control room, control each mud delivery pipe to grout respectively, confirm whether slurry flows out from each mud injection hole 214 on the beam splitter 2 and the grouting hole on the mud delivery pipe, and observe whether the mud flow rate can be controlled by the grouting pump system;

[0049] Logic simulation: Perform a control simulation, such as manually inputting "No. 3 pipe stress increases" information, and observe whether the grouting pump system accurately executes the "increase the grouting amount of the No. 3 pipe corresponding to the slurry delivery pipe" instruction.

[0050] Step S4, back dragging operation and stress monitoring;

[0051] Start the reamer 4, the reamer 4 pulls the beam splitter 2 in front of the hole and each HDPE pipe travels in the hole, start the grouting pump system, keep injecting stable flow of mud into the hole at an initial normal pressure. During the back dragging process, the stress monitoring device 5 transmits stress change information to the data acquisition instrument, the data acquisition instrument transmits abnormal data of a certain HDPE pipe to the grouting pump system by comparing the stress information of each HDPE pipe, and the grouting pump system controls the mud injection flow size of the corresponding HDPE pipe in real time.

[0052] Specifically, when the stress of a certain pipe appears abnormal and severe fluctuations, and its adjacent HDPE pipe also has stress change phenomenon, it indicates that the HDPE pipe has a local jamming or winding trend, the system determines that there is a winding risk, and the grouting pump system will automatically increase the mud injection flow of the corresponding HDPE pipe until the tension data of the corresponding HDPE pipe tends to be stable. When each HDPE pipe shows increased tension, it represents that the overall resistance is large during the back dragging process, then the grouting pump system increases the mud injection flow of all HDPE pipes until the tension data is balanced and falls back. This dynamic regulation process ensures that the stress distribution of each HDPE pipe during the entire back dragging process is more uniform, avoiding the risk of HDPE pipe damage or jamming caused by local stress concentration. In addition, a warning threshold can also be set in the system, such as setting the warning threshold to 30% of the average stress value of each HDPE pipe in this project. When the stress difference between each HDPE pipe exceeds the warning threshold, the system determines that there is stress imbalance, and then automatically increases the mud injection flow of the HDPE pipe with imbalance until the tension data of this part falls within the warning threshold.

[0053] Step S5, back dragging is completed, site cleaning and withdrawal;

[0054] Under the stress monitoring and control, four HDPE pipes are back dragged out of the hole at one time. After removing the reamer 4, the beam splitter 2, the tension sensor at the front end of the HDPE pipe and other related devices and equipment, and finishing the work on site, the site is cleaned up and the topography and environment are restored.

[0055] Further, such as Figure 2As shown, in another embodiment of the present application, the one-time synchronous back-towing of the pipe group consisting of 12 HDPE pipes is required, and the construction conditions are more complex. In order to improve the convenience of construction, the splitter 2 is selected to adopt a modular design structure that is spliced with each other, and multiple splitters 2 can be spliced into a rigid whole according to the number of one-time back-towing pipe groups. Specifically, a single splitter 2 includes a main body 21 and a rigid channel 22 passing through the main body 21, the ends of the main body 21 are respectively fixedly provided with a lug plate 211, and the side wall is fixedly provided with a lug 212, the lug plate 211 and the lug 212 are provided with thread holes that correspond to each other, the lug 212 can be embeddedly installed between the lug plates 211 of another splitter 2 main body 21, and two splitters 2 are connected by inserting a screw rod into the thread holes.

[0056] Further, the mud injection hole is arranged at the edge of the rigid channel 22, the side wall of the main body 21 is provided with a pipe groove 216, and the pipe groove 216 is provided with a grouting inlet 215, the pipe groove 216 is used to accommodate the mud delivery pipe connected to the grouting inlet 215, and the existence of the mud delivery pipe is avoided to affect the connection of multiple splitters 2.

[0057] Through the modular design, the back-towing demand of different number and specification of HDPE pipe groups 1 can be flexibly adapted, and the combination mode of the splitter 2 can be adjusted according to the actual needs during the construction process, so as to optimize the overall construction scheme. The lug plate 211 and the lug 212 of the splitter 2 adopt a precision machining process to ensure the tightness and stability of the connection part, and avoid the problems of HDPE pipe deviation or stress concentration caused by loose connection. At the same time, in order to enhance the durability and fatigue resistance of the splitter 2, the main body 21 is made of high-strength alloy steel and is subjected to special surface hardening treatment such as carburizing or nitriding treatment to improve its surface hardness and wear resistance; the ball bearings 221 inside the rigid channel 22 are made of ceramic matrix composite material, which has excellent wear resistance and self-lubricating performance, and can maintain stable performance in long-term high-load operation.

[0058] Further, as shown in Figure 3 、 4 , the device for improving the smoothness of back-towing can be further added in step S2 of the anti-winding and stress uniformity control method for synchronous back-towing of the HDPE pipe group of the present application. Specifically:

[0059] A adapter 3 is connected between the reamer 4 and the splitter 2, the adapter 3 includes a connecting plate 31 connected with the splitter 2 and the HDPE pipe, and a rotating shaft 32 fixedly connected with the connecting plate 31, one end of the rotating shaft 32 is connected with the reamer 4, and the inside of the rotating shaft 32 is a bearing structure, and the end connected with the reamer 4 can rotate axially.

[0060] During the back-dragging process, due to the arrangement of the adapter 3, the rotating torque of the reamer 4 is directly transmitted to the adapter 3, and the rotating shaft 32 rotates through its bearing, so that the rotating torque of the reamer 4 is no longer transmitted backward, thereby avoiding the direct influence of the rotation of the reamer 4 on the splitter 2 and the HDPE pipe group 1, effectively optimizing the mechanical transmission relationship between the reamer 4 and the splitter 2, reducing the torsional stress of the HDPE pipe caused by torque transmission, and further improving the stability and safety of the back-dragging process.

[0061] It should be noted that the above only discloses the preferred embodiments of the present application, and of course cannot limit the scope of the present application, and those skilled in the art can understand that the above-mentioned embodiments can be implemented in whole or in part, and equivalent changes made according to the claims of the present application still belong to the scope covered by the present application.

Claims

1. A method for preventing winding and controlling stress distribution of HDPE pipe group synchronous back-dragging, characterized in that, Synchronous back-reaming of HDPE pipe group using beam splitter and stress monitoring device, comprising the following steps: Step S1, drilling a guide hole; drilling a guide hole in the soil layer using horizontal directional drilling, and making a reaming plan; Step S2, equipment preparation; select a reamer according to the reaming plan, and select a beam splitter with several rigid channels; the beam splitter is provided with a grouting inlet for connecting a mud delivery pipe; the number of rigid channels is the same as the number of HDPE pipes, the inner wall is embedded with several high-strength wear-resistant balls, and the edge is provided with several mud injection holes, which are connected to one grouting inlet in a group of one rigid channel; Step S3, equipment assembly; connect the beam splitter behind the reamer, insert each HDPE pipe to be back-reamed into the rigid channel of the beam splitter after numbering, and connect the reamer; connect each group of grouting inlets at one end of the mud delivery pipe, and connect a multi-channel independent control grouting pump system at the other end; the mud delivery pipe is provided with several grouting holes at equal intervals; install a stress monitoring device at the connection part of the HDPE pipe group and the beam splitter, the stress monitoring device is connected to a data acquisition instrument on the ground through a wire, and the data acquisition instrument is linked with the grouting pump system; Step S4, back-reaming operation and stress monitoring; start the reamer, the reamer pulls the beam splitter and the HDPE pipe group in the hole; start the grouting pump system and continuously inject mud into the hole; during back-reaming, the stress monitoring device transmits the stress change information of each pipe in the HDPE pipe group to the data acquisition instrument, the data acquisition instrument compares the stress information of each HDPE pipe, transmits abnormal data to the grouting pump system, and the grouting pump system controls the size of the mud injection flow of the HDPE pipe with abnormal stress in real time; Step S5, back-reaming is completed, the site is cleaned and withdrawn; under the stress monitoring and control of step S4, the HDPE pipe group is back-reamed synchronously; after the related devices and equipment are removed, the site is cleaned up, the topography and environment are restored.

2. The method according to claim 1, wherein, In step S1, the reaming plan adopts a staged reaming process, step S1 reams the hole to the previous level of the final hole size, and in step S3, the last level of the reamer is connected with the beam splitter and the HDPE pipe group to be back-reamed.

3. The method according to claim 1, wherein, In step S3, the mud delivery pipe and the wire are respectively fixed on the outer wall of the HDPE pipe in the axial direction of the HDPE pipe in a spiral winding manner.

4. The method according to claim 1, wherein, In step S3, the stress monitoring device is a high-precision tension sensor for measuring the absolute tension of each HDPE pipe.

5. The method according to claim 4, wherein, After the equipment assembly in step S3 is completed, the following tests are carried out: Sensor test: drill the reamer into a short distance from the hole, and observe whether the data acquisition instrument normally reads the tension data of each HDPE pipe; Grouting test: start the grouting pump system in the control room, control each mud delivery pipe for grouting respectively, confirm whether grout flows out of the mud injection holes of the beam splitter and the grouting holes on the mud delivery pipe, and observe whether the mud flow can be controlled by the grouting pump system; Logical simulation: perform a control simulation, manually input a certain tube stress rise information, and observe whether the grouting pump system accurately executes the instruction of increasing the grouting amount of the mud delivery pipe corresponding to the certain tube.

6. The method according to claim 1, wherein, The beam splitter is a modular unit, multiple beam splitters can be spliced with each other, and a single beam splitter includes a main body and a rigid channel arranged through the main body.

7. The method according to claim 6, wherein, The end of the main body is fixedly provided with a lug plate, and the side wall is fixedly provided with a lug, and the lug plate and the lug are provided with thread holes matched with each other, the lug can be embedded between the lug plates on the main bodies of other beam splitters, and each beam splitter is connected by inserting a screw rod into the thread holes.

8. The method according to claim 7, wherein, The side wall of the main body is provided with a pipe groove, and the pipe groove is provided with a grouting inlet, and the pipe groove is used for accommodating a mud delivery pipe connected with the grouting inlet.

9. The method according to claim 1, wherein, In step S3, an adapter is connected between the reamer and the beam splitter, the adapter includes a connecting plate and a rotating shaft fixed to the connecting plate, the connecting plate is used for connecting the beam splitter and the HDPE pipe, the other end of the rotating shaft is connected with the reamer, the inside of the rotating shaft is a bearing structure, and the end of the rotating shaft connected with the reamer can rotate axially.

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