Anti-winding and uniform stress distribution control method for synchronous pull-back of HDPE (high-density polyethylene) pipe group

Abstract

The invention relates to the technical field of construction engineering non-excavation, in particular to an anti-winding and uniform stress distribution control method for synchronous back dragging of an HDPE pipe group. The method specifically comprises the steps that in pipe group back dragging construction, a beam splitter is connected to the rear end of a reamer, HDPE pipes are inserted into rigid channels corresponding to the beam splitter correspondingly, so that the pipe group serves as an integral system to conduct back dragging construction, stress monitoring is conducted on the HDPE pipes in the back dragging process with the assistance of a stress monitoring device, and grouting flow is controlled through a grouting pump system; and the pipeline friction force in the back dragging process is reasonably reduced. The beam splitter is arranged and the stress of the pipe group is monitored in the pipe group back dragging construction, so that the winding possibility of each HDPE pipe is reduced, the construction process can be monitored, the stress balance of each pipe in the back dragging process is ensured, the overload risk of a single pipe is reduced to the minimum, the HDPE pipe is prevented from being damaged in the back dragging process, and the service life of the HDPE pipe is prolonged. And on the whole, the construction accident rates of winding, pipe clamping, snapping and the like during back dragging construction of the HDPE pipe group are greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of pipeline construction technology, and in particular to a method for preventing entanglement and controlling stress distribution during synchronous pullback of HDPE pipe groups. Background Technology

[0002] In municipal power and telecommunications pipeline projects, trenchless laying of HDPE pipes using horizontal directional drilling (HDPE) is one of the current mainstream techniques. The main construction process involves first drilling a pilot hole using a horizontal directional drilling rig, then enlarging the pilot hole with a reamer, and finally simultaneously pulling the HDPE pipes back into the pre-formed borehole. However, under conditions of long-distance pullback, curved borehole trajectories, and soft soil, when multiple HDPE pipes are pulled back in parallel, the pipe group is easily twisted and entangled due to the irregular inner wall of the borehole, the curved trajectory, and geological flow. This not only easily leads to scratches on the outer wall of the HDPE pipes, affecting their service life, but may also create stress concentration at the entanglement points, causing the pipe group to get stuck in the borehole and resulting in pullback failure.

[0003] Furthermore, due to the imperfect uniformity of borehole enlargement and the local differences in formation resistance, the stress distribution of the total tensile force on each HDPE pipe is extremely uneven in the initial pullback stage, especially when pulling back to the curved sections of the borehole. Some HDPE pipes may bear tensile forces far exceeding the average value. This can lead to uneven progress of the reamer, resulting in an uneven borehole enlargement path during pullback, or even cause some HDPE pipes to be damaged or broken due to overload. The situation is more complex with longer pipeline pullbacks and more bends, making this risk of breakage even more pronounced in these construction scenarios. This uneven stress distribution severely limits the number and length of pipelines that can be pulled back at one time, affecting construction efficiency and safety.

[0004] Traditional construction methods often involve welding multiple HDPE pipes into a rigid assembly for pullback. However, in practice, this approach has several drawbacks. First, the monolithic pipe group hinders the later maintenance and replacement of individual HDPE pipes. Second, the lack of flexibility makes it impossible to address the varying stress distribution of each pipe, hindering passage through bends and tunnels. Furthermore, stress concentration issues in individual pipes can be reflected across the entire pipe group, increasing the risk during pullback. Ultimately, this often necessitates relying on manual experience to simply increase grout flow for lubrication, a crude and ineffective method. Therefore, developing a method to effectively prevent HDPE pipe entanglement during synchronous pullback and to achieve uniform stress distribution is of great significance. Summary of the Invention

[0005] The present invention aims to solve the problems in the prior art, where the traditional synchronous pullback construction method for HDPE pipe groups cannot effectively prevent pipe entanglement, which can cause pipe damage or jamming, and the uneven stress distribution during the pullback process can lead to pipe tearing and breakage.

[0006] To address the aforementioned technical problems, this invention provides a method for preventing entanglement and controlling stress distribution during synchronous pullback of HDPE pipe groups. This method monitors and manages the pullback construction of the pipe group as a whole system by installing bundle splitters and stress monitoring devices on the pipe group. The main steps include: Step S1, pilot hole drilling; use a horizontal directional drill to drill into the soil layer to form a pilot hole, and formulate a hole enlargement plan; Step S2, Equipment preparation; Select a hole expander according to the hole expansion scheme, and prepare a bundle splitter with several rigid channels; The bundle splitter is provided with a grouting inlet for connecting the mud conveying 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 several mud injection holes are provided on the edge. The mud injection holes are connected to a grouting inlet in a group of rigid channels. Step S3, equipment assembly; connect the bundle splitter after the reamer, number each HDPE pipe to be pulled back and insert it into the rigid channel on the bundle splitter, and connect the reamer; connect one end of the mud delivery pipe to each group of grouting inlets, and the other end to a multi-channel independently controlled grouting pump system, the mud delivery pipe has several grouting holes at equal intervals; install stress monitoring devices at the connection points between the HDPE pipe group and the bundle splitter, the stress monitoring devices are connected to the ground data acquisition instrument through wires, and the data acquisition instrument is linked with the grouting pump system; Step S4, pullback operation and stress monitoring; start the reamer, which pulls the bundle splitter and HDPE pipe group forward in the borehole; start the grouting pump system to continuously inject mud into the borehole; during the pullback process, 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 and transmits the abnormal data to the grouting pump system. The grouting pump system controls the mud injection flow rate corresponding to the HDPE pipe with abnormal stress in real time. Step S5: Pullback completed, site cleanup and removal; Under the stress monitoring and control of step S4, the HDPE pipe group is pulled back synchronously and pulled out from the hole outlet; After removing the relevant devices and equipment and carrying out the finishing work on site, the site is cleaned up and the terrain and environment are restored.

[0007] Furthermore, in step S1, the hole enlargement scheme adopts a graded hole enlargement process. Step S1 enlarges the hole to the level before the final hole diameter level. In step S3, the hole enlarger of the last level is connected to the bundle splitter and the HDPE pipe group to be pulled back.

[0008] Furthermore, in step S3, the mud conveying pipe and the wire are fixed to the outer wall of the HDPE pipe in a spiral winding manner along the axis of the HDPE pipe.

[0009] Furthermore, in step S3, the stress monitoring device is a high-precision tension sensor used to measure the absolute tensile force borne by each HDPE pipe.

[0010] Furthermore, after the equipment assembly is completed in step S3, the following tests are performed: Sensor test: Drill the expander a short distance into the hole and observe whether the data acquisition instrument can read the tensile data of each HDPE pipe normally; Grouting test: Start the grouting pump system in the control room, control each mud delivery pipe to grout, confirm whether grout flows out from each mud injection hole of the splitter and the grouting hole on the mud delivery pipe, and observe whether the mud flow rate can be controlled by the grouting pump system. Logic simulation: Execute a control simulation, manually input information about the stress increase of a certain pipe, and observe whether the grouting pump system accurately executes the instruction to increase the grouting volume of the mud delivery pipe corresponding to that pipe.

[0011] Furthermore, the beam splitter is a modular unit, and multiple beam splitters can be spliced ​​together. A single beam splitter includes a main body and a rigid channel that runs through the main body.

[0012] Furthermore, the ends of the main body are respectively fixedly provided with protruding plates, and the side walls are fixedly provided with protrusions. The protruding plates and protrusions are provided with matching threaded holes. The protrusions can be embedded between the protruding plates on other beam splitter bodies, and the beam splitters are connected by inserting screws into the threaded holes.

[0013] Furthermore, the side wall of the main body has a pipe groove, and a grouting inlet is provided in the pipe groove. The pipe groove is used to accommodate the mud conveying pipe connected to the grouting inlet.

[0014] Furthermore, in step S3, an adapter is connected between the expander and the splitter. The adapter includes a connecting plate that connects the splitter and the HDPE pipe, and a rotating shaft fixed to the connecting plate. The other end of the rotating shaft is connected to the expander. The rotating shaft has a bearing structure inside, and the end of the rotating shaft connected to the expander can rotate axially.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: During the synchronous pullback construction of HDPE pipes, a bundle splitter is introduced to independently confine each HDPE pipe within its own rigid channel, preventing contact between the pipes at the source and effectively preventing direct friction and potential entanglement. Furthermore, during the pullback process, a stress monitoring device provides real-time feedback on the stress status of the HDPE pipes, and the frictional resistance of each pipe during pullback is adjusted by regulating the slurry injection flow rate, further reducing the possibility of entanglement. This invention, through the above technical solution, makes the construction process monitorable, ensuring balanced stress on each pipe during pullback and minimizing the risk of single-pipe overload. Overall, this invention significantly reduces the rate of construction accidents such as entanglement, pipe jamming, and breakage during HDPE pipe pullback construction, ensuring the long-term safety of the pipeline network and reducing the huge economic losses caused by construction failures. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0017] Figure 1 This is a cross-sectional schematic diagram of a synchronous pullback construction scenario for HDPE pipe groups according to the first embodiment of the present invention; Figure 2 This is a schematic diagram of the overall structure of the beam splitter according to the second embodiment of the present invention; Figure 3 This is a schematic diagram of the overall structure connecting the various components in this invention; Figure 4 This is a schematic diagram of the adapter structure in this invention.

[0018] In the attached diagram: 1. HDPE pipe group; 2. Bundle splitter; 21. Main body; 211. Protruding plate; 212. Protrusion; 213. Threaded hole; 214. Mud injection hole; 215. Grouting inlet; 216. Pipe groove; 22. Rigid channel; 221. Ball bearing; 3. Adapter; 31. Connecting plate; 32. Rotating shaft; 4. Hole expander; 5. Stress monitoring device. Detailed Implementation

[0019] The technical solution of the present invention will now be described with reference to the accompanying drawings. However, the described embodiments are only some embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] 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.

[0021] 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.

[0022] 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: Step S1, drilling the pilot hole; 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.

[0023] Step S2, Equipment preparation; Based on the hole-expansion scheme, the final stage hole expander 4 is selected, and a bundle splitter 2 with four rigid channels 22 is prepared simultaneously. Each rigid channel 22 is used to accommodate one HDPE pipe. The inner diameter of the rigid channels 22 on the bundle splitter 2 is slightly larger than the diameter of the HDPE pipe and is arranged in a 2×2 rectangle. The inner wall is embedded with several high-strength wear-resistant balls 221. The bundle splitter 2 is about 1.5m long and has a cross-sectional dimension of 480mm×480mm. The bundle splitter 2 is also provided with several mud injection holes 214 distributed on the edge of the rigid channels 22. The mud injection holes 214 are grouped with a single rigid channel 22. Each group of mud injection holes 214 is connected to a grouting inlet 215. The grouting inlet 215 is used to connect to an external mud delivery pipe.

[0024] The use of the bundle splitter 2 allows each HDPE pipe front section to be independently confined within its own rigid channel 22, avoiding contact between the HDPE pipes at the source, thereby preventing entanglement caused by direct friction between the front HDPE pipes during the back-dragging process of the pipe group.

[0025] During the pullback process, the movement of the HDPE pipe is mainly affected by the traction force of the expander 4 and the frictional resistance of the inner wall of the hole. The HDPE pipe itself has an elastic structure, which will cause elastic creep inside the HDPE pipe due to the traction force. The ball bearings 221 set 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 expansioner 4 digs in by rotating itself, and the rotational torque generated may be transmitted to the HDPE pipe or the bundle splitter 2, causing the HDPE pipe or the bundle splitter 2 to rotate slightly. The ball bearings 221 set in the rigid channel 22 can allow the HDPE pipe or the bundle splitter 2 to rotate slightly, preventing the rotation of the HDPE pipe or the bundle splitter 2 from affecting each other and causing the HDPE pipe or the bundle splitter 2 to generate mutually resisting torsional forces that would damage them. Moreover, this rotation can also improve the passage of the HDPE pipe at certain bending positions in the hole, further reducing the overall resistance during the movement of the HDPE pipe group 1.

[0026] Step S3, equipment assembly; After the final 650mm reamer 4, connect the bundle splitter 2. After numbering each HDPE pipe, insert the four HDPE pipes into the rigid channel 22 on the bundle splitter 2 and connect them to the reamer 4. Connect one end of the mud delivery pipe to each group of grouting inlets 215. The mud delivery pipe is tightly fixed to the outer wall of the HDPE pipe in a spiral winding manner along the axis of the HDPE pipe and has several grouting holes opened at equal intervals. The other end of the mud delivery pipe is connected to a multi-channel independently controlled grouting pump system.

[0027] High-precision tension sensors are installed at the front end of each HDPE pipe, near the connection point of the bundle splitter 2, as stress monitoring devices 5, to measure the absolute tensile force borne by each HDPE pipe. The stress monitoring device 5 is connected to a data acquisition instrument on the ground via a wire. The wire is tightly fixed to the outer wall of the HDPE pipe in a spiral winding manner along the axial direction of the HDPE pipe. The data acquisition instrument is linked to the grouting pump system.

[0028] During the pullback process, each HDPE pipe is a flexible body with significant elasticity, bearing the traction force from the expander 4. The overall mechanical relationship is basically equivalent to: the total traction force of the expander 4 = the tension at the head of the HDPE pipe = the sum of all local frictional resistances of the HDPE pipe from the front section to the rear section.

[0029] Therefore, the control strategy implemented by the data acquisition instrument and the grouting pump system is as follows: when the stress data of a certain HDPE pipe is significantly greater than the average stress of other HDPE pipes, the slurry injection flow rate of the current HDPE pipe should be increased. Specifically, during the travel of the HDPE pipe, the soil at different locations on the inner wall of the borehole will bring different frictional resistance to each HDPE pipe, especially when passing through some bends in the borehole, where the different frictional resistances of the inner and outer bends will be directly applied to HDPE pipes located at different positions. When a certain HDPE pipe passes through a certain position, the frictional resistance increases, which is reflected in the increased tension on the HDPE pipe. Therefore, it is necessary to increase the slurry injection flow rate to reduce the frictional resistance between the HDPE pipe and the inner wall of the borehole, thereby reducing its tension and avoiding the tensile damage caused by uneven stress on the HDPE pipe. In addition, when the middle and rear sections of each HDPE pipe come into contact with each other, the frictional resistance between them will also cause changes in the tension of the contacting HDPE pipes. When the slurry injection flow rate of the corresponding HDPE pipe is increased, the frictional resistance between HDPE pipes will be reduced because the slurry delivery pipe is spirally wound and fixed along the outer wall of the HDPE pipe and has several grouting holes at equal intervals. This will further reduce the risk of mutual entanglement caused by frictional contact between HDPE pipes.

[0030] Before the formal pullback, after the expansion joint 4, the bundle splitter 2, and the HDPE pipe group 1 are connected, they should be tested at the hole opening to verify that the connections of each component are normal, and the following system tests should be performed: Sensor test: Drill a short distance into the 4-way hole of the expander and observe whether the data acquisition instrument can read the tensile data of each HDPE pipe normally; Grouting test: Start the grouting pump system in the control room, control each mud delivery pipe to grout, confirm whether there is grout flowing out of each mud injection hole 214 on the 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. Logic simulation: Execute a control simulation, such as manually inputting the information "stress increase in pipe No. 3", and observe whether the grouting pump system accurately executes the instruction to "increase the grouting volume of the mud delivery pipe corresponding to pipe No. 3".

[0031] Step S4: Pullback operation and stress monitoring; The reamer 4 is activated, pulling the bundle splitter 2 and each HDPE pipe forward within the borehole. The grouting pump system is then started, maintaining an initial, normal pressure to inject a stable flow of grout into the borehole. During the pullback process, the stress monitoring device 5 transmits stress change information to the data acquisition instrument. The data acquisition instrument compares the stress information of each HDPE pipe and transmits abnormal data for a specific HDPE pipe to the grouting pump system. The grouting pump system then controls the grout injection flow rate of the corresponding HDPE pipe in real time.

[0032] Specifically, when the stress of a certain pipe fluctuates abnormally and drastically, and its adjacent HDPE pipes also show stress changes, it indicates that the HDPE pipe is experiencing localized jamming or entanglement. The system determines that there is a risk of entanglement, and the grouting pump system will automatically increase the slurry injection flow rate of the corresponding HDPE pipe until the tensile strength data of the corresponding HDPE pipe stabilizes. When all HDPE pipes show increased tensile strength, it indicates that the overall resistance during the pullback process is large. In this case, the grouting pump system increases the slurry injection flow rate of all HDPE pipes until the tensile strength data falls back to a balanced level. This dynamic control process ensures a more uniform stress distribution in each HDPE pipe throughout the pullback process, avoiding the risk of HDPE pipe damage or jamming due to localized stress concentration. In addition, a warning threshold can be set in the system. For example, in this project, the warning threshold is set to 30% of the average stress value of each HDPE pipe. When the stress difference between HDPE pipes exceeds the warning threshold, the system determines that a stress imbalance has occurred and automatically increases the slurry injection flow rate of the HDPE pipe with the imbalance until the tensile strength data of that part falls back to within the warning threshold.

[0033] Step S5: Towing back is complete; site cleanup and removal. Under stress monitoring and control, the four HDPE pipes were pulled back synchronously in one go and pulled out from the hole outlet. After removing the hole expander 4, bundle splitter 2, tension sensor at the front end of the HDPE pipe, and other related devices and equipment, the site was cleaned up and the terrain and environment were restored.

[0034] Furthermore, such as Figure 2 As shown, in another embodiment of the present invention, it is necessary to simultaneously pull back a pipe group consisting of 12 HDPE pipes at one time, which makes the construction conditions more complex. In order to improve the construction convenience, the selected bundle splitter 2 adopts a modular design structure of mutual splicing. Multiple bundle splitters 2 can be spliced ​​together into a rigid whole according to the number of pipe groups pulled back at one time. Specifically, a single bundle splitter 2 includes a main body 21 and a rigid channel 22 that passes through the main body 21. The ends of the main body 21 are respectively fixedly provided with protruding plates 211, and the side walls are fixedly provided with protrusions 212. The protruding plates 211 and protrusions 212 are provided with corresponding threaded holes. The protrusions 212 can be embedded and installed between the protruding plates 211 on the main body 21 of another bundle splitter 2, and the two bundle splitters 2 are connected by inserting a screw into the threaded hole.

[0035] Furthermore, the mud injection hole is located at the edge of the rigid channel 22, and the side wall of the main body 21 has a pipe groove 216. The pipe groove 216 is provided with a grouting inlet 215. The pipe groove 216 is used to accommodate the mud conveying pipe connected to the grouting inlet 215, so as to avoid the presence of the mud conveying pipe affecting the connection between the multiple splitters 2.

[0036] Through modular design, it can flexibly adapt to the pullback requirements of HDPE pipe groups 1 with different quantities and specifications. It also facilitates the adjustment of the combination method of the bundle splitter 2 according to actual needs during construction, thereby optimizing the overall construction plan. The protrusions 211 and 212 of the bundle splitter 2 are made with precision machining technology to ensure the tightness and stability of the connection parts, avoiding HDPE pipe displacement or stress concentration problems caused by loose connection. At the same time, in order to enhance the durability and fatigue resistance of the bundle splitter 2, the main body 21 is made of high-strength alloy steel and undergoes special surface hardening treatment, such as carburizing or nitriding, 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 properties, and can maintain stable performance during long-term high-load operation.

[0037] Furthermore, such as Figure 3 , 4 As shown, in step S2 of the anti-winding and stress distribution control method for synchronous pullback of HDPE pipe groups in this invention, the following device can be further added to improve the smoothness of the pullback. Specifically: An adapter 3 is connected between the expander 4 and the splitter 2. The adapter 3 includes a connecting plate 31 that connects the splitter 2 and the HDPE pipe, and a rotating shaft 32 that is fixedly connected to the connecting plate 31. The other end of the rotating shaft 32 is connected to the expander 4. The rotating shaft 32 has a bearing structure inside, and the end connected to the expander 4 can rotate axially.

[0038] During the pullback process, due to the adapter 3, the rotational torque of the expander 4 is directly transmitted to the adapter 3, while the rotating shaft 32 rotates through its own bearing, so that the rotational torque of the expander 4 is no longer transmitted backward. This avoids the direct impact of the expander 4's rotation on the splitter 2 and HDPE pipe group 1, effectively optimizing the mechanical transmission relationship between the expander 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 pullback process.

[0039] It should be noted that the above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the present invention.

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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