Anti-settlement method for pipe roof advance support construction

Abstract

The present invention discloses a method for preventing subsidence in pipe-roof advance support construction, comprising the following steps: drilling a first compensating grouting hole above a target borehole for the pipe-roof advance support and installing a first grouting pipe in the first compensating grouting hole; monitoring ground subsidence above the target borehole for the pipe-roof advance support; and, when ground subsidence is detected, grouting the soil layer above the target borehole for the pipe-roof advance support through the first grouting pipe to restore ground subsidence. The technical solution of the present invention can reduce ground subsidence above the pipe-roof advance support.

Description

Technical Field

[0001] The invention relates to the technical field of pipe-roof advance support construction, and in particular to an anti-settlement method for pipe-roof advance support construction. Background Art

[0002] Pipe-roof advance support is a pre-excavation support structure used in shallow underground excavation projects. Essentially, thick-walled steel pipes are pre-drilled and installed above the proposed underground tunnel or structure. This provides temporary advance support, preventing soil collapse and ground subsidence, and ensuring the safe operation of excavation and subsequent support processes.

[0003] The existing pipe-roof advance support construction method first uses an anchor drill to drill a hole parallel to the tunnel axis, then inserts a steel pipe. This construction method makes it difficult to prevent ground subsidence above the pipe-roof advance support during the drilling process. If rail transit is operating above the pipe-roof advance support, significant subsidence can affect its normal operation. Therefore, a method for preventing subsidence during pipe-roof advance support construction is needed to reduce ground subsidence above the pipe-roof advance support. Summary of the Invention

[0004] The main purpose of the present invention is to provide a method for preventing subsidence in pipe-roof advance support construction, aiming to reduce ground subsidence above the pipe-roof advance support.

[0005] To achieve the above-mentioned object, the present invention proposes a method for preventing subsidence in pipe-roof advance support construction, comprising the following steps:

[0006] Drilling a first compensation grouting hole above the target borehole of the pipe-roof advance support, and installing a first grouting pipe in the first compensation grouting hole;

[0007] Monitor ground settlement above the target borehole for pipe-roof advance support;

[0008] When ground settlement is monitored, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support to restore the ground settlement.

[0009] Optionally, the steps of drilling a first compensation grouting hole above a target borehole for pipe-roof advance support and installing a first grouting pipe in the first compensation grouting hole include:

[0010] Drill the first compensation grouting hole above the target drill hole for pipe-roof advance support;

[0011] Cleaning the gravel in the first compensating grouting hole;

[0012] Extending the first grouting pipe into the first compensation grouting hole;

[0013] pouring cement slurry into the gap between the outer side surface of the first grouting pipe and the inner wall surface of the first compensation grouting hole through the first grouting pipe;

[0014] Clean the inner wall surface of the first grouting pipe.

[0015] Optionally, in the step of drilling a first compensating grouting hole above the target borehole of the pipe-roof advance support, the first compensating grouting hole extends along the extension direction of the target borehole of the pipe-roof advance support, and the remaining undrilled length in the extension direction of the first compensating grouting hole is less than or equal to 1m.

[0016] Optionally, the step of monitoring ground settlement above a target borehole for pipe-roof advance support includes:

[0017] A plurality of detection points are arranged on the ground above the first compensation grouting hole, and the plurality of detection points are arranged at intervals along the extension direction of the first compensation grouting hole;

[0018] The settlement of each inspection point was monitored using a total station.

[0019] Optionally, when ground subsidence is detected, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support to restore the ground subsidence.

[0020] When the monitored ground settlement is greater than 5mm and does not exceed 10mm, the maximum grouting pressure is the maximum cover pressure plus the additional pressure, and the value range of the additional pressure is 200kPa to 500kPa;

[0021] When the ground settlement is monitored to be more than 10 mm, the maximum grouting pressure is 1500 kPa.

[0022] Optionally, when the ground settlement is monitored to be greater than 5 mm and not more than 10 mm, each 1000 L of cement slurry contains: 350 kg of MFC9000, 3.5 L of dispersant, and 883 L of water.

[0023] Optionally, when the ground settlement is monitored to be more than 10 mm, each 1000 L of cement slurry contains 35 kg of bentonite, 450 kg of cement, and 830 L of water.

[0024] Optionally, before monitoring the ground settlement above the target borehole for pipe-roof advance support, the method further includes:

[0025] A second compensating grouting hole is drilled above the designed drilling position of the first compensating grouting hole, and a second grouting pipe is installed in the second compensating grouting hole to restore ground settlement.

[0026] Optionally, a second compensating grouting hole is drilled above the designed drilling position of the compensating grouting hole, and a second grouting pipe is installed in the second compensating grouting hole. In the step of restoring ground subsidence, the distance between the second compensating grouting hole and the ground is less than or equal to 1.5m.

[0027] Optionally, before drilling a first compensating grouting hole above a target borehole for pipe-roof advance support and installing a first grouting pipe in the first compensating grouting hole, the method includes:

[0028] A row of cofferdam piles is driven into the ground above both ends of the target borehole for pipe roof advance support;

[0029] Drilling a plurality of grouting holes in the ground between the two rows of cofferdam piles at an angle downward;

[0030] A third grouting pipe is installed in the slit grouting hole, and cement slurry is poured into the soil layer through the third grouting pipe to reinforce the soil layer.

[0031] The technical solution of the present invention drills a first compensating grouting hole above the target borehole of the pipe-roof advance support and installs a first grouting pipe in the first compensating grouting hole. Ground settlement above the target borehole of the pipe-roof advance support is monitored. When ground settlement is detected, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support to restore ground settlement, thereby filling the gaps in the soil layer that have caused settlement due to drilling into the target borehole of the pipe-roof advance support, thereby reducing ground settlement above the pipe-roof advance support. This solves the problem of ground settlement caused during the current construction of pipe-roof advance support. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0033] Figure 1 This is a flow chart of the first embodiment of the anti-settlement method for pipe-roof advance support construction according to the present invention;

[0034] Figure 2 This is a flow chart of a second embodiment of the method for preventing subsidence in pipe-roof advance support construction according to the present invention;

[0035] Figure 3 This is a flow chart of a third embodiment of the method for preventing subsidence in pipe-roof advance support construction according to the present invention;

[0036] Figure 4This is a flow chart of a fourth embodiment of the method for preventing subsidence in pipe-roof advance support construction according to the present invention;

[0037] Figure 5 This is a flow chart of the fifth embodiment of the anti-settlement method for pipe-roof advance support construction according to the present invention.

[0038] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0041] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] The present invention provides a method for preventing subsidence in pipe-roof advance support construction.

[0043] like Figure 1 As shown, in one embodiment of the pipe-roof advance support construction anti-settlement method of the present invention, the pipe-roof advance support construction anti-settlement method includes the following steps:

[0044] S10, drilling a first compensating grouting hole above a target borehole for pipe-roof advance support, and installing a first grouting pipe in the first compensating grouting hole;

[0045] S30, monitoring ground settlement above the target borehole for pipe-roof advance support;

[0046] S50: When ground subsidence is detected, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support to restore the ground subsidence.

[0047] Specifically, pipe-roof advance support is an advance support structure used during shallow buried underground excavation of underground structural engineering. The anti-settlement method for pipe-roof advance support construction is a method to reduce the settlement of the ground above the pipe-roof advance support during construction. The target drilling holes for pipe-roof advance support refer to the installation holes that need to be drilled in the design for installing steel pipes in pipe-roof advance support. During the process of target drilling holes for pipe-roof advance support, settlement is mainly caused by the formation of cracks in the soil layer during the drilling process, and the soil layer above presses down on the cracks to cause settlement; the soil layer is vibrated during the drilling process, and crushed stone or soil fills the original cracks, which manifests as settlement of the ground above.

[0048] Furthermore, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support system. The grouting fills the gaps in the soil layer, thus stopping the settlement. High-pressure grouting is then continued into the soil layer to expand the gaps, which manifests as ground settlement recovery. It should be noted that settlement recovery here refers to recovery to a certain settlement value. Similarly, monitoring ground settlement means determining ground settlement when it exceeds a certain value.

[0049] It can be understood that the technical solution of the present invention monitors the ground settlement above the target borehole of the pipe-roof advance support, drills a first compensating grouting hole above the target borehole of the pipe-roof advance support, and installs a first grouting pipe in the first compensating grouting hole. When ground settlement is detected, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support to restore ground settlement, thereby reducing ground settlement above the pipe-roof advance support. This solves the problem of ground settlement caused by the current construction process of pipe-roof advance support, and is particularly important for working conditions with high ground settlement requirements. For example, when there is ground rail transit above the pipe-roof advance support, large settlement will affect the normal operation of the rail transit above.

[0050] It's important to note that pipe-roof advance support typically requires multiple steel pipes. Therefore, there are multiple target boreholes for this purpose. Correspondingly, each target borehole has a first compensating grouting hole above it, meaning there are multiple first grouting pipes. During actual construction, any area of ​​ground settlement is corrected by grouting the corresponding first grouting pipes.

[0051] Please refer to Figure 2 In some embodiments of the anti-settlement method for pipe-roof advance support construction of the present invention, the steps of drilling a first compensating grouting hole above a target borehole for pipe-roof advance support and installing a first grouting pipe in the first compensating grouting hole include:

[0052] S11, drilling the first compensation grouting hole above the target drill hole of the pipe-roof advance support;

[0053] S12, cleaning gravel in the first compensating grouting hole;

[0054] S13, extending the first grouting pipe into the first compensation grouting hole;

[0055] S14, pouring cement slurry into the gap between the outer side surface of the first grouting pipe and the inner wall surface of the first compensation grouting hole through the first grouting pipe;

[0056] S15, cleaning the inner wall surface of the first grouting pipe.

[0057] In this embodiment, the first compensating grouting hole can be drilled using a drilling machine, or can be drilled using an anchor drilling machine, or can be other effective drilling methods. The method of cleaning the gravel in the first compensating grouting hole can be to flush it out with high-pressure water, or to dig it out with a rod, or can be other effective methods of cleaning the gravel in the first compensating grouting hole. A number of grouting holes are provided on the wall of the first grouting pipe around the axis. The grouting holes connect the inside of the pipe with the outside world. The specific number of grouting holes can be set according to the actual needs of the project, and will not be repeated here. A rubber sleeve is provided on the outer wall of the first grouting pipe. The rubber sleeve blocks the grouting hole. The liquid in the pipe requires a certain pressure to open the rubber sleeve, allowing the liquid in the pipe to flow out of the pipe, so that the rubber sleeve acts as a one-way valve for the grouting hole. The specific pressure of opening the rubber sleeve can be selected according to the actual needs of the project. Among them, the material or thickness of the rubber sleeve can be changed to change the opening pressure, which will not be repeated here.

[0058] Specifically, cement slurry is input into the first grouting pipe. After the cement slurry reaches a certain pressure, the rubber sleeve is stretched open, and the cement slurry flows into the gap between the outer wall of the first grouting pipe and the inner wall of the first compensating grouting hole, filling the gap to form a sheath slurry that wraps the first grouting pipe. Then, the inner wall of the first grouting pipe is cleaned with clean water for the next use. After the cement slurry solidifies, the first grouting pipe is fixedly installed in the first compensating grouting hole. In this way, the first grouting pipe can be firmly installed and the gap can be filled to prevent settlement. In addition, after the cement slurry fills the gap and solidifies, it can prevent the next grouting from overflowing from the gap at the inlet end of the first grouting pipe. It should be noted that when settlement occurs and the first grouting pipe is used, high-pressure cement slurry is input into the first grouting pipe. The high-pressure cement slurry breaks up the solidified sheath slurry, thereby actually injecting cement slurry into the soil layer.

[0059] Please refer to Figure 1In some embodiments of the anti-settlement method for pipe-roof advance support construction of the present invention, in the step of drilling a first compensating grouting hole above the target drill hole of the pipe-roof advance support, the first compensating grouting hole extends along the extension direction of the target drill hole of the pipe-roof advance support, and the remaining undrilled length in the extension direction of the first compensating grouting hole is less than or equal to 1m.

[0060] In this embodiment, the remaining undrilled length of the first compensating grouting hole in the extension direction is less than or equal to 1m, which means that the first compensating grouting hole can be drilled through only by the remaining depth, and the remaining depth is less than or equal to 1m. Specifically, the target borehole of the pipe-roof advance support needs to be drilled through, while the first compensating grouting hole does not need to be drilled through. When the first compensating grouting hole is drilled through only by the remaining depth, drilling is stopped, so that the difference between the length of the first compensating grouting hole and the length of the target borehole of the pipe-roof advance support is less than or equal to 1m. When ground subsidence occurs during the drilling of the target borehole of the pipe-roof advance support, high-pressure cement slurry is poured into the first compensating grouting hole through the first grouting pipe, covering most of the length of the target borehole of the pipe-roof advance support. As a result, the injected cement slurry has a larger diffusion range, and there is a greater probability that the cement slurry will fill the gaps in the production settlement, thereby preventing settlement. Continuing to pressurize can restore settlement.

[0061] Please refer to Figure 3 In some embodiments of the anti-settlement method for pipe-roof advance support construction of the present invention, the step of monitoring ground settlement above the target borehole of the pipe-roof advance support includes:

[0062] A plurality of detection points are arranged on the ground above the first compensation grouting hole, and the plurality of detection points are arranged at intervals along the extension direction of the first compensation grouting hole;

[0063] The settlement of each inspection point was monitored using a total station.

[0064] In this embodiment, a plurality of detection points are set on the ground above the first compensating grouting hole. These detection points are manually set detection locations. The number of detection points can be 2, 3, 4, 5, etc., and the specific number can be set based on the actual project. The settlement of each detection point is monitored using a total station, and each detection point can be monitored using an automatic total station.

[0065] Specifically, by setting up several detection points at intervals along the extension direction of the first compensating grouting hole, the ground settlement in the length direction of the target borehole of the pipe-roof advance support can be monitored, thereby improving the settlement detection accuracy during the drilling of the target borehole of the pipe-roof advance support.

[0066] It should be noted that when there are multiple target boreholes for pipe-roof advance support, there are correspondingly several detection points above the target boreholes of each pipe-roof advance support, so that all the detection points can form a monitoring network, which covers all the target boreholes of pipe-roof advance support on the ground.

[0067] Please refer to Figure 1 In some embodiments of the anti-settlement method for pipe-roof advance support construction of the present invention, when ground settlement is monitored, grouting the soil layer above the target borehole of the pipe-roof advance support through the first grouting pipe to restore the ground settlement is performed.

[0068] When the monitored ground settlement is greater than 5mm and does not exceed 10mm, the maximum grouting pressure is the maximum cover pressure plus the additional pressure, and the value range of the additional pressure is 200kPa to 500kPa;

[0069] When the ground settlement is monitored to be more than 10 mm, the maximum grouting pressure is 1500 kPa.

[0070] In this embodiment, the grouting pressure is not uniform, and the grouting pressure gradually increases from a low level. The backfill pressure is also not uniform. Taking the maximum backfill pressure can make the grouting pressure always greater than the backfill pressure, so that settlement can be effectively prevented by grouting into the soil layer. Specifically, when it is monitored that the ground settlement is greater than 5mm and not more than 10mm, the following can be adopted first: the maximum grouting pressure is the maximum backfill pressure plus the additional pressure, and the value range of the additional pressure is 200kPa~500kPa. Then continue to monitor the ground settlement. If the ground continues to settle, when it is monitored that the ground settlement exceeds 10mm, the maximum grouting pressure is 1500kPa. In this way, different pressure grouting can be performed according to different working conditions. On the one hand, cement slurry of different pressures can be injected into the soil layer according to different degrees of settlement to effectively prevent settlement. On the other hand, the higher the pressure, the more energy is required. Therefore, performing different pressure grouting according to different working conditions can save energy. And it is safer.

[0071] Please refer to Figure 1 In some embodiments of the anti-subsidence method for pipe-roof advance support construction of the present invention, when the ground settlement is monitored to be greater than 5 mm and not more than 10 mm, each 1000L of cement slurry contains: 350kg of MFC9000, 3.5L of dispersant, and 883L of water.

[0072] In this embodiment, MFC9000 refers to a cement model. When ground settlement is detected to be greater than 5 mm but not exceeding 10 mm, a dispersant is a substance that improves the rheological properties of the cement slurry, also known as a cement diffusing agent. Specifically, when ground settlement is detected to be greater than 5 mm but not exceeding 10 mm, a cement slurry is injected into the soil layer. The cement slurry has a formula of 350 kg of MFC9000, 3.5 L of dispersant, and 883 L of water per 1000 L of cement slurry. This improves the fluidity of the cement slurry, allowing it to quickly reach the cracks causing the settlement and restore the ground settlement.

[0073] Please refer to Figure 1 In some embodiments of the anti-subsidence method for pipe-roof advance support construction of the present invention, when the ground settlement is monitored to be more than 10 mm, each 1000 L of cement slurry contains 35 kg of bentonite, 450 kg of cement, and 830 L of water.

[0074] In this embodiment, bentonite is a non-metallic mineral with montmorillonite as its primary mineral component. Adding bentonite to cement can make the cement highly hygroscopic and expansive. Specifically, when ground settlement exceeds 10 mm, a cement slurry is injected into the soil layer. The slurry has a formula of 35 kg of bentonite, 450 kg of cement, and 830 L of water per 1000 L of slurry. This increases the density of the slurry, allowing it to fill the gaps that caused the settlement and restore the ground.

[0075] Please refer to Figure 4 In some embodiments of the method for preventing subsidence in pipe-roof advance support construction of the present invention, before monitoring ground subsidence above a target borehole for pipe-roof advance support, the method further includes:

[0076] S20: Drill a second compensating grouting hole above the designed drilling position of the first compensating grouting hole, and install a second grouting pipe in the second compensating grouting hole to restore ground settlement.

[0077] In this embodiment, the designed drilling position of the first compensating grouting hole refers to the drilling position of the first compensating grouting hole. The method of installing the second grouting pipe in the second compensating grouting hole can refer to the installation method of the first grouting pipe in the first compensating grouting hole in the above embodiment. Specifically, when settlement occurs, cement slurry can be poured into the soil layer through the second grouting pipe to restore the ground settlement. By drilling the second compensating grouting hole above the designed drilling position of the first compensating grouting hole and installing the second grouting pipe in the second compensating grouting hole, the overall grouting range can be further expanded, so that when settlement occurs, settlement can be prevented or restored, with rapid onset and significant effect.

[0078] Please refer to Figure 4In some embodiments of the anti-subsidence method for pipe-roof advance support construction of the present invention, a second compensating grouting hole is drilled above the designed drilling position of the compensating grouting hole, and a second grouting pipe is installed in the second compensating grouting hole. In the step of restoring ground settlement, the distance between the second compensating grouting hole and the ground is less than or equal to 1.5m.

[0079] In this embodiment, a second compensating grouting hole is drilled above the designed drilling position of the compensating grouting hole. The distance between the second compensating grouting hole and the ground is less than or equal to 1.5m. A second grouting pipe is installed in the second compensating grouting hole. In this way, because the distance between the second compensating grouting hole and the ground is less than or equal to 1.5m, grouting into the soil layer through the second grouting pipe can effectively lift the ground and effectively restore settlement. In addition, the first grouting pipe and the second grouting pipe can form two grouting areas in the vertical direction. The first grouting pipe is closer to the target borehole of the pipe-roof advance support. Since settlement occurs when drilling the target borehole of the pipe-roof advance support, the first grouting pipe can effectively prevent and restore settlement at the source of settlement through grouting. Since the first grouting pipe is far away from the ground, relying solely on the first grouting pipe to restore ground settlement requires a large grouting pressure and places high demands on equipment. Therefore, setting a second grouting pipe in the soil layer close to the ground can effectively restore ground settlement with significant results. Moreover, compared with using the first grouting pipe to restore the same settlement, the grouting pressure is smaller, which can save energy.

[0080] Please refer to Figure 5 In some embodiments of the anti-settlement method for pipe-roof advance support construction of the present invention, before drilling a first compensating grouting hole above a target borehole for pipe-roof advance support and installing a first grouting pipe in the first compensating grouting hole, the method includes:

[0081] S1: Drive a row of cofferdam piles into the ground above both ends of the target borehole for pipe-roof advance support.

[0082] S2, drilling a plurality of grouting holes in the ground between the two rows of cofferdam piles at an inclined downward angle;

[0083] S3, installing a third grouting pipe in the slit grouting hole, and pouring cement slurry into the soil layer through the third grouting pipe to reinforce the soil layer.

[0084] In this embodiment, the cofferdam piles are constructed retaining structures, and their function is to prevent soil loss. The target borehole of the pipe-roof advance support has two ends, one end is the initial end, and the other end is the terminal end. The initial end and the terminal end of the target borehole of the pipe-roof advance support are respectively located on two sections. A row of cofferdam piles are driven into the ground above the two ends of the target borehole of the pipe-roof advance support, which can prevent the soil loss on the section and the occurrence of settlement during the drilling of the target borehole of the pipe-roof advance support. Specifically, a number of slit grouting holes are drilled obliquely downward on the ground between the two rows of cofferdam piles to form a fan-shaped grouting area. The gaps in the soil layer can be filled through the third grouting pipe to reinforce the soil layer, thereby further reducing the occurrence of ground settlement.

[0085] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preventing subsidence in pipe-roof advance support construction, characterized in that: The steps include: Drilling a first compensation grouting hole above the target borehole of the pipe-roof advance support, and installing a first grouting pipe in the first compensation grouting hole; Monitor ground settlement above the target borehole for pipe-roof advance support; When ground subsidence is detected, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support to restore the ground subsidence; Before drilling a first compensation grouting hole above a target borehole for pipe-roof advance support and installing a first grouting pipe in the first compensation grouting hole, the method includes: A row of cofferdam piles is driven into the ground above both ends of the target borehole for pipe roof advance support; Drilling a plurality of grouting holes in the ground between the two rows of cofferdam piles at an angle downward; Installing a third grouting pipe in the slit grouting hole, and pouring cement slurry into the soil layer through the third grouting pipe to reinforce the soil layer; Before monitoring ground settlement above the target borehole for pipe-roof advance support, it also includes: Drilling a second compensating grouting hole above the designed drilling position of the first compensating grouting hole, and installing a second grouting pipe in the second compensating grouting hole to restore ground subsidence; A second compensating grouting hole is drilled above the designed drilling position of the compensating grouting hole, and a second grouting pipe is installed in the second compensating grouting hole to restore ground settlement. The distance between the second compensating grouting hole and the ground is less than or equal to 1.5m.

2. The anti-settlement method for pipe-roof advance support construction according to claim 1, characterized in that: The steps of drilling a first compensation grouting hole above a target borehole of pipe-roof advance support and installing a first grouting pipe in the first compensation grouting hole include: Drill the first compensation grouting hole above the target drill hole for pipe-roof advance support; Cleaning the gravel in the first compensating grouting hole; Extending the first grouting pipe into the first compensation grouting hole; pouring cement slurry into the gap between the outer side surface of the first grouting pipe and the inner wall surface of the first compensation grouting hole through the first grouting pipe; Clean the inner wall surface of the first grouting pipe.

3. The anti-settlement method for pipe-roof advance support construction according to claim 2, characterized in that: In the step of drilling a first compensating grouting hole above a target borehole of the pipe-roof advance support, the first compensating grouting hole extends along an extension direction of the target borehole of the pipe-roof advance support, and a remaining undrilled length in the extension direction of the first compensating grouting hole is less than or equal to 1 m.

4. The anti-settlement method for pipe-roof advance support construction according to claim 1, characterized in that: The steps for monitoring ground settlement above the target borehole for pipe-roof advance support include: A plurality of detection points are arranged on the ground above the first compensation grouting hole, and the plurality of detection points are arranged at intervals along the extension direction of the first compensation grouting hole; The settlement of each inspection point was monitored using a total station.

5. The anti-settlement method for pipe-roof advance support construction according to claim 1, characterized in that: When ground subsidence is detected, grouting is performed through the first grouting pipe into the soil layer above the target borehole of the pipe-roof advance support to restore the ground subsidence. When the monitored ground settlement is greater than 5mm and less than 10mm, the maximum grouting pressure is the maximum cover pressure plus the additional pressure, and the value range of the additional pressure is 200kPa~500kPa; When the ground settlement is monitored to be more than 10 mm, the maximum grouting pressure is 1500 kPa.

6. The anti-settlement method for pipe-roof advance support construction according to claim 5, characterized in that: When the ground settlement is monitored to be greater than 5mm and not more than 10mm, each 1000L cement slurry contains: MFC9000 350kg, dispersant 3.5L, and water 883L.

7. The anti-settlement method for pipe-roof advance support construction according to claim 5, characterized in that: When the ground settlement is monitored to be more than 10 mm, each 1000 L of cement slurry contains 35 kg of bentonite, 450 kg of cement and 830 L of water.

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