Soft rock roadway bottom plate combined anchor cable bundle reinforcing method

Abstract

The invention relates to the technical field of coal mine roadway surrounding rock control, and provides a soft rock roadway bottom plate combined anchor cable bundle reinforcing method which comprises the steps that structure detection is conducted on surrounding rocks at different depths of a roadway bottom plate; anchoring drill holes are constructed in the roadway bottom plate according to the detection result, and the diameter of each anchoring drill hole is 60-100 mm; a combined anchor cable is installed in the anchoring drill hole; the roadway bottom plate is grouted through the combined anchor cable, and the combined anchor cable is tensioned and pre-tightened after grouting anchoring; the anchoring effect can be improved by adopting large-diameter drilling, and the stability of surrounding rock is enhanced; the deformation and the damage of the surrounding rock can be more effectively resisted; besides, the large-diameter drill hole provides a larger space for grouting, so that a gap between the drill hole and the anchor cable can be filled with a grouting material more sufficiently, the uniformity and compactness of grouting are improved, the anchoring effect is further enhanced, especially for soft rocks or broken surrounding rocks, the large-diameter drill hole can better adapt to complex geological conditions, and the grouting efficiency is improved. And a more reliable supporting effect is provided.

Description

Technical Field

[0001] The invention relates to the technical field of surrounding rock control of coal mine tunnels, and in particular to a combined anchor cable bundle reinforcement method for a soft rock tunnel floor. Background Art

[0002] There are a large number of soft rock mines in the western mining areas of my country. The surrounding rocks of the tunnels have the characteristics of low strength, poor cementation, mud and softening after contact with water, making tunnel maintenance difficult. Under the interaction of water and force, the mudstone of the tunnel floor has serious bottom bulging, and the floor needs to be reinforced and supported by installing floor anchor rods and cables. However, the anchoring structure of the floor anchor rods and cables has suffered extensive damage and instability, and the anchoring force of the anchor rods and cables is seriously insufficient. According to statistics, the general anchoring force of the anchor rods and cables of the water-degraded soft rock floor is only 90-150kN, which cannot effectively play the role of active support of the anchor rods and cables, resulting in serious deformation and damage to the tunnel. The "double low" anchoring force and preload force cannot give full play to the high strength and high stiffness of the anchor support system. The floor can only be reinforced with high density on site.

[0003] This is mainly because the surrounding rock of the tunnel bottom plate is mainly mudstone and sandy mudstone, which has low strength and seriously deteriorates when exposed to water. The strength of mudstone is greatly reduced under the action of water and force, and the mudstone-anchor agent interface fails to bond and separate. Various support forms such as anchor mesh spraying and anchor injection have been tried, but the bottom drum deformation is serious and requires continuous repairs. Summary of the invention

[0004] The invention provides a combined anchor cable bundle reinforcement method for a soft rock tunnel floor, which is used to solve the problem of floor bulging deformation of a soft rock tunnel floor in a coal mine in the prior art.

[0005] The present invention provides a soft rock tunnel floor combined anchor bundle reinforcement method, comprising: Conduct structural detection of surrounding rocks at different depths of the tunnel floor; According to the detection results, anchor holes are constructed on the tunnel floor, and the diameter of the anchor holes is 60-100mm; installing a combined anchor cable in the anchor borehole; The combined anchor cables are used to inject grout into the tunnel floor, and the combined anchor cables are tensioned and pre-tightened after grouting and anchoring.

[0006] According to the soft rock tunnel floor combined anchor bundle reinforcement method provided by the present invention, the anchor drilling for the tunnel floor is constructed according to the detection results, comprising: Excavating an arc-shaped groove on the bottom plate of the roadway, constructing a plurality of anchoring boreholes in the arc-shaped groove, wherein the depth of the anchoring boreholes is determined according to the detection results; An inverted bottom arch beam is laid in the arc-shaped groove, and a plurality of anchor cable holes are reserved in the inverted bottom arch beam. The number of the anchor cable holes is the same as that of the anchoring drill holes, and the positions thereof correspond one to one.

[0007] According to the soft rock tunnel floor combined anchor cable bundle reinforcement method provided by the present invention, the combined anchor cable is installed in the anchor borehole, comprising: Installing a combined anchor cable into the corresponding single anchor borehole through each anchor cable hole; A plurality of the combined anchor cables are connected by an inverted arch beam.

[0008] According to the soft rock tunnel floor combined anchor bundle reinforcement method provided by the present invention, the maximum depth of the arc-shaped groove is 500-800 mm.

[0009] According to the soft rock tunnel floor combined anchor bundle reinforcement method provided by the present invention, the depth of the anchoring borehole is 6-15m.

[0010] According to the combined anchor bundle reinforcement method for the soft rock tunnel floor provided by the present invention, the structural detection of the surrounding rocks at different depths of the tunnel floor comprises: A detection borehole is constructed on the tunnel floor, the depth of the detection borehole is 15-20m; Ultrasonic detectors, strength meters and peep instruments are used to conduct all-round rock structure detection on the surrounding rocks at different depths of the bottom plate to determine the damage range, strength and joint and fissure distribution of the bottom plate surrounding rocks.

[0011] According to the soft rock tunnel floor composite anchor cable reinforcement method provided by the present invention, the composite anchor cable comprises an anchor grouting anchor cable, a splitting grouting anchor cable and a spare grouting anchor cable, and the three anchor cables are all hollow structures. The anchor grouting anchor cable, the splitting grouting anchor cable and the spare grouting anchor cable are connected by a circular perforated support plate to form the composite anchor cable.

[0012] According to the soft rock tunnel floor combined anchor cable reinforcement method provided by the present invention, grouting is performed on the tunnel floor through the combined anchor cable, and the combined anchor cable is tensioned and pre-tightened after grouting and anchoring, and then the method further includes: Pouring concrete into the arc-shaped groove to fill it up and form a concrete inverted bottom arch; Construct two reserved grouting holes for later re-injection, insert grouting iron pipes, and complete the hole sealing.

[0013] According to the soft rock tunnel floor combined anchor bundle reinforcement method provided by the present invention, the spacing of the grouting holes is 2-3m, and the row spacing is 2-3m.

[0014] The method for reinforcing the bottom plate of a soft rock tunnel provided by the present invention further comprises: A mobile monitoring base station is arranged on the bottom plate of the tunnel to monitor the displacement of the bottom plate of the tunnel in real time; a preload monitoring instrument is arranged at the tail of the combined anchor cable to monitor the stress condition of the anchor cable in real time during the mining process of the working face.

[0015] The present invention provides a method for reinforcing a soft rock tunnel floor with a combined anchor cable bundle, comprising: performing structural detection on surrounding rocks at different depths of the tunnel floor; constructing anchor holes on the tunnel floor according to the detection results, wherein the diameter of the anchor holes is 60-100 mm; installing combined anchor cables in the anchor holes; grouting the tunnel floor with the combined anchor cables, and pre-tensioning the combined anchor cables after grouting and anchoring. The present invention can improve the anchoring effect and enhance the stability of the surrounding rock by using large-diameter drilling holes; on the one hand, it can increase the contact area between the anchor structure and the surrounding rock, thereby It improves the anchoring force; on the other hand, a larger borehole diameter can accommodate larger diameter anchor cables, providing stronger tensile and shear resistance, and helping to more effectively resist deformation and damage to the surrounding rock; in addition, large-diameter boreholes provide a larger space for grouting, allowing the grouting material to more fully fill the gap between the borehole and the anchor cable, improving the uniformity and density of the grouting, and further enhancing the anchoring effect. In particular, for soft rock or broken surrounding rock, large-diameter boreholes can better adapt to complex geological conditions and provide more reliable support effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of an anchoring drill hole and a combined anchor cable provided in an embodiment of the present invention.

[0018] Figure 2 It is a schematic diagram of a tunnel cross section provided by an embodiment of the present invention.

[0019] Reference numerals: 1. Anchor drilling; 2. Anti-bottom arch beam; 3. Anchor grouting anchor cable; 4. Split grouting anchor cable; 5. Spare grouting anchor cable; 6. Concrete anti-bottom arch; 7. Grouting iron pipe. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Combine the following Figure 1-Figure 2The invention describes a method for reinforcing a soft rock tunnel floor with a combined anchor bundle.

[0022] The embodiment of the present invention provides a method for reinforcing a soft rock tunnel floor with a combined anchor bundle, comprising: Step 101: Conduct structural detection of the surrounding rock at different depths of the tunnel floor. Through a detailed geological survey of the tunnel floor, the effectiveness and safety of subsequent reinforcement measures can be ensured. By implementing this step, the specific conditions of the floor surrounding rock can be accurately understood, so as to design a more reasonable and effective reinforcement plan.

[0023] In some embodiments, first, detection holes are drilled in the tunnel floor construction, and the depth of the detection holes is 15-20m; then, ultrasonic detectors, strength meters and peeps can be used to conduct all-round rock structure detection on the surrounding rocks at different depths of the floor to determine the damage range, strength and joint and fissure distribution of the floor surrounding rocks, in preparation for the subsequent installation of combined anchor cables, ensuring that the anchor cables can penetrate deep into the surrounding rocks to achieve the expected reinforcement effect.

[0024] Step 102: construct anchoring borehole 1 on the tunnel floor according to the detection result, and the diameter of anchoring borehole 1 is 60-100 mm.

[0025] With such a configuration, the diameter of the conventional anchoring borehole 1 is only 28-36 mm. By adopting a large diameter borehole, the anchoring effect can be improved and the stability of the surrounding rock can be enhanced. On the one hand, the contact area between the anchoring structure and the surrounding rock can be increased, thereby increasing the anchoring force. On the other hand, a larger borehole diameter can accommodate anchor cables with larger diameters, providing stronger tensile and shear resistance, and helping to more effectively resist deformation and damage of the surrounding rock. In addition, a large diameter borehole provides a larger space for grouting, allowing the grouting material to more fully fill the gap between the borehole and the anchor cable, thereby improving the uniformity and density of the grouting and further enhancing the anchoring effect. In particular, for soft rock or broken surrounding rock, a large diameter borehole can better adapt to complex geological conditions and provide a more reliable support effect. Among them, the borehole depth should be determined according to the surrounding rock conditions and design requirements, and is usually matched with or slightly shallower than the depth of the detection borehole to ensure that the anchor cable can cover the key areas that need to be reinforced.

[0026] Step 103: Install the combined anchor cable in the anchor borehole 1.

[0027] Step 104: Grouting is performed into the bottom plate of the tunnel through the combined anchor cable, and the combined anchor cable is tensioned and pre-tightened after grouting and anchoring. Cement slurry or other suitable grouting materials are injected into the borehole through the combined anchor cable, and the gap between the combined anchor cable and the anchoring borehole 1 is fully filled by grouting. During the grouting process, it is necessary to ensure that the slurry is evenly distributed to avoid the occurrence of voids or looseness. The grouting pressure should be appropriate and can penetrate into the cracks of the surrounding rock, but will not cause excessive rupture of the surrounding rock, so as to ensure that the slurry is further strengthened through grouting and the connection between the anchor cable and the surrounding rock is improved, thereby improving the overall support effect; the anchor cable is tensioned to the pre-tightening force required by the design through the tensioning equipment, so as to ensure that the combined anchor cable can play an effective role, so that the combined anchor cable is closely combined with the surrounding rock to form an effective support system.

[0028] In a specific embodiment, constructing anchor boreholes 1 on the tunnel floor according to the detection results in step 102 includes step 1021: excavating an arcuate groove on the tunnel floor, constructing multiple anchor boreholes 1 in the arcuate groove, and the depth of the anchor borehole 1 is determined according to the detection results; optionally, the depth of the anchor borehole 1 is 6-15m, and the maximum depth of the arcuate groove is 500-800mm.

[0029] Among them, the location where the anchor borehole 1 needs to be constructed is the key area that needs to be reinforced, especially the place where the surrounding rock conditions are poor or there are cracks. At the determined drilling location, an arc-shaped trench is excavated. The shape and size of the arc-shaped trench should be determined according to actual needs. Usually the width and depth should be sufficient to accommodate the drilling equipment and subsequent construction operations. Multiple anchor boreholes 1 are constructed in one section of the arc-shaped trench. The number and layout of the boreholes should be determined according to the detection results and design requirements, which can be 2, 3, 4 or more, to ensure that the anchor borehole 1 can cover the key area that needs to be reinforced. It should be noted that multiple anchor boreholes 1 should be symmetrically arranged in one section of the arc-shaped trench.

[0030] The method further includes step 1022: laying an inverted bottom arch beam 2 in the arc-shaped groove, reserving a plurality of anchor cable holes in the inverted bottom arch beam 2, wherein the number of the anchor cable holes is the same as the anchoring drill holes 1 and the positions correspond one to one.

[0031] Specifically, the anti-bottom arch beam 2 is usually made of reinforced concrete or other high-strength materials, which plays a supporting and reinforcing role. The shape and size of the anti-bottom arch beam 2 should match the arc groove to ensure that it can be firmly fixed in the groove; multiple anchor boreholes 1 are constructed in the arc groove, and the number and layout of the anchor boreholes 1 should be determined according to the detection results and design requirements to ensure that the anchor boreholes 1 can cover the key areas that need to be reinforced, and multiple anchor cable holes are reserved in the anti-bottom arch beam 2. The number and position of the anchor cable holes should correspond to the number and position of the anchor boreholes 1 one by one to ensure that each anchor cable can accurately pass through the anti-bottom arch beam 2 and dock with the borehole, wherein the diameter of the anchor borehole 1 is 60-100mm to increase the contact area between the anchor structure and the surrounding rock and provide greater anchoring force. The depth of the anchor borehole 1 should be determined according to the detection results, usually 6-15m. The specific depth should ensure that the anchor cable can cover the key areas that need to be reinforced, while avoiding excessive depth that increases construction difficulty and costs.

[0032] In this embodiment, the step 103 of installing the combined anchor cable in the anchor borehole 1 includes: installing the combined anchor cable into the corresponding single anchor borehole 1 through each anchor cable hole; and connecting a plurality of combined anchor cables through the anti-bottom arch beam 2 .

[0033] Specifically, a combined anchor cable is installed through each anchor cable hole into the corresponding single anchor borehole 1, one end of the combined anchor cable is passed through the anchor cable hole of the anti-bottom arch beam 2, and then extended into the anchor borehole 1, and a temporary fixing device is used to preliminarily fix the combined anchor cable at the borehole mouth to ensure that the combined anchor cable does not slip; a tensioning device such as a hydraulic jack is installed at the other end of the combined anchor cable, and the tensioning device is used to tension the combined anchor cable to the preload force required by the design. The size of the preload force should be determined according to the surrounding rock conditions and design requirements. After the tensioning is completed, a locking device is used to lock the combined anchor cable in the tensioning position to ensure that the combined anchor cable does not rebound; thereafter, multiple combined anchor cables are connected through the anti-bottom arch beam 2, and the anchor cables are fixed at both ends or specific positions of the anti-bottom arch beam 2 to ensure that the anchor cables are firmly connected to the anti-bottom arch beam 2 to form an integrated support system.

[0034] In this embodiment, the combined anchor cable includes an anchor grouting anchor cable 3, a splitting grouting anchor cable 4 and a spare grouting anchor cable 5. All three anchor cables are hollow structures. The anchor grouting anchor cable 3, the splitting grouting anchor cable 4 and the spare grouting anchor cable 5 are connected to form a combined anchor cable through a circular perforated support plate.

[0035] In some specific embodiments, step 104 includes: connecting the anchor grouting system at the tail of the anchor grouting anchor cable 3 for grouting, the anchor grouting system is a product in the prior art, including equipment such as a grouting pump and a grouting pipe, and its structure and principle are not the focus of this article and will not be repeated here; the grouting material is a water-resistant non-Newtonian fluid fast-solidifying material, the water-resistant non-Newtonian fluid fast-solidifying material has good durability and corrosion resistance, can effectively prevent the erosion of moisture and corrosive media, and extend the service life of the anchor cable, the initial setting strength of this material can reach 5MPa within 2-4 hours, and when the anchor material is slurried back to the orifice of the anchor borehole 1, the grouting is stopped; after the anchor grouting anchor cable 3 completes grouting and anchoring, after waiting for 4 hours, the anchor grouting anchor cable 3, the splitting grouting anchor cable 4 and the spare grouting anchor cable 5 can be subjected to the first tensioning and pre-tightening of the anchor cable pre-tightening force, and the pre-tightening force is controlled at 200kN.

[0036] Wait for 1 day, then connect the splitting grouting system at the tail of the splitting grouting anchor cable 4 to carry out splitting grouting, and the splitting grouting pressure reaches 2Mpa. After the splitting grouting is completed, the anchor grouting anchor cable 3, the splitting grouting anchor cable 4 and the spare grouting anchor cable 5 are tensioned and pre-tightened for the second time, and the pre-tightening force is controlled at 400kN.

[0037] Wait for 7 days, then connect the grouting system at the tail of the spare grouting anchor cable 5 for grouting, and the splitting grouting pressure reaches 5Mpa. After that, the anchor grouting anchor cable 3, the splitting grouting anchor cable 4 and the spare grouting anchor cable 5 are tensioned and pre-tightened for the third time, and the pre-tightening force is controlled at 600-800kN.

[0038] The present invention realizes multi-level grouting reinforcement through preliminary grouting, splitting grouting and standby grouting, ensures that the slurry in the anchoring borehole 1 is fully filled, and improves the anchoring effect; by gradually increasing the preload force in stages from 200kN to 400kN and then to 600-800kN, the stability and bearing capacity of the anchor cable at different stages are ensured; the staged grouting and tensioning preload make the force on the anchor cable more uniform in all directions, avoid local stress concentration, effectively prevent the deformation of the anchor cable and the surrounding rock and soil, and improve the overall stability of the structure.

[0039] In this embodiment, step 105 is also included: pouring concrete into the arc groove to fill it up to form a concrete anti-bottom arch 6. By pouring concrete on the anti-bottom arch beam 2 to form a solid supporting body, the concrete anti-bottom arch 6 improves the stability and bearing capacity of the bottom plate and prevents the bottom plate from sinking and deforming.

[0040] With such an arrangement, slippage between the anti-bottom arch beam 2 and the bottom plate can be prevented by pouring concrete, thereby ensuring the reliability and stability of the structure. The concrete is tightly combined with the anti-bottom arch beam 2, the combined anchor cable and the grouting material to form an integral structure, which significantly improves the overall stiffness and stability of the bottom plate. The filled concrete layer can effectively prevent local deformation of the groove area, ensuring that the entire bottom plate is more uniform when subjected to stress, avoiding local stress concentration, thereby improving the bending resistance and bearing capacity of the bottom plate, making the area more stable when subjected to stress, and reducing the possibility of deformation.

[0041] Specifically, after the anchor cable is installed and grouting is completed, the arc groove on the tunnel floor is cleaned to ensure that there are no debris and loose rocks, and concrete is poured to ensure that the concrete fully fills the groove. A vibrator can be used to compact the groove to avoid bubbles and voids. After the concrete is poured, the surface is leveled and maintained to ensure that the concrete reaches the designed strength. By pouring concrete in the arc groove to fill it, the flatness of the tunnel floor is restored, and the overall strength of the floor is increased.

[0042] Preferably, after step 105, step 106 is further included: constructing two reserved grouting holes for later re-injection, and inserting the grouting iron pipe 7 to complete the hole sealing. Figure 2 As shown, two grouting holes are constructed at a section of the tunnel, and a grouting iron pipe 7 is inserted. Sealing materials, such as cement mortar or special sealing materials, are filled around the grouting iron pipe 7 to ensure that the gap between the grouting iron pipe 7 and the drilled hole is completely filled. A vibrating rod or a hand tool is used to compact the sealing material to ensure the sealing effect. After the sealing material is cured, the sealing effect is checked to ensure that the sealing between the grouting iron pipe 7 and the drilled hole is good and there is no leakage.

[0043] Optionally, the spacing of the grouting holes is 2-3m, and the row spacing is 2-3m. That is, the spacing is 2-3m between two grouting holes at a section of the tunnel, and the row spacing is 2-3m between the grouting holes between two adjacent tunnel sections along the length of the tunnel.

[0044] With such arrangement, the reserved grouting holes provide flexibility for subsequent re-injection, and grouting can be carried out at any time according to actual conditions, further enhancing the reinforcement effect; the reserved grouting holes can reduce the drilling work during subsequent re-injection, saving time and cost, and by inserting the grouting iron pipe 7 and sealing the hole, the long-term stability and reliability of the grouting hole are ensured, and leakage of grouting material or loosening of surrounding rock is avoided. The insertion and sealing of the grouting iron pipe 7 are simple and easy to control, ensuring the safety of the construction process.

[0045] In this embodiment, step 107 is also included: a mobile monitoring base station is arranged on the tunnel floor to monitor the displacement of the tunnel floor in real time.

[0046] Specifically, mobile monitoring base stations can be arranged at key positions of the tunnel floor, especially in areas prone to displacement. Suitable fixing devices can be used to install the mobile monitoring base stations on the tunnel floor to ensure that the base stations are stable and avoid displacement of the base stations due to vibration or external force. Displacement sensors are then arranged around the base stations. The sensors can be surface displacement meters, crack meters or optical fiber sensors, etc., which are used to monitor the displacement of the tunnel floor in real time. The sensors are calibrated and tested to ensure their normal operation and accurate data collection.

[0047] In addition, a preload monitoring instrument is arranged at the tail of the combined anchor cable to monitor the stress condition of the anchor cable in real time during the mining process of the working face.

[0048] Specifically, preload monitoring instruments are arranged at the tail of the combined anchor cables. These positions should be able to fully cover all anchor cables, especially the key anchor cables that are subjected to greater forces. The preload monitoring instruments are installed at the tail of the anchor cables to ensure that the instruments are tightly connected to the anchor cables to avoid inaccurate data due to looseness. The preload monitoring instruments are connected to a mobile monitoring base station or an external control system to ensure that data can be transmitted in real time. The preload monitoring instruments are calibrated and tested to ensure that they work properly and can accurately collect the force data of the anchor cables.

[0049] This embodiment collects the displacement data of the tunnel floor and the force data of the anchor cable in real time through a mobile monitoring base station and a preload monitoring instrument. The collected data can be transmitted to an external control system or monitoring platform by wireless or wired means for data analysis so as to timely discover potential problems. The early warning thresholds of displacement and force can be set according to design requirements and empirical data. When the monitoring data exceeds the early warning threshold, the system sends out an alarm signal. According to the alarm information, emergency measures are taken in time, such as re-tensioning the anchor cable, supplementing grouting or strengthening support, etc., to ensure the safety of the tunnel. It is possible to issue an alarm in time at the early stage of a problem to avoid accidents, and through data analysis, the support plan can be optimized, the reinforcement effect can be improved, and the construction cost can be reduced.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for reinforcing the floor of a soft rock tunnel with a combined anchor bundle, characterized in that: include: Conduct structural detection of surrounding rocks at different depths of the tunnel floor; According to the detection results, anchoring holes (1) are constructed on the tunnel floor, wherein the diameter of the anchoring holes (1) is 60-100 mm; Installing a combined anchor cable in the anchoring borehole (1); The combined anchor cables are used to inject grout into the tunnel floor, and the combined anchor cables are tensioned and pre-tightened after grouting and anchoring.

2. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 1 is characterized in that: The method of constructing anchor holes (1) on the tunnel floor according to the detection results comprises: Excavating an arc-shaped groove on the bottom plate of the tunnel, constructing a plurality of anchoring boreholes (1) in the arc-shaped groove, wherein the depth of the anchoring boreholes (1) is determined according to the detection results; An inverted bottom arch beam (2) is laid in the arc-shaped groove, and a plurality of anchor cable holes are reserved in the inverted bottom arch beam (2), wherein the number of the anchor cable holes is the same as that of the anchoring boreholes (1) and the positions correspond one to one.

3. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 2 is characterized in that: The step of installing a combined anchor cable in the anchoring borehole (1) comprises: Installing a combined anchor cable into the corresponding single anchor borehole (1) through each anchor cable hole; A plurality of the combined anchor cables are connected via an anti-bottom arch beam (2).

4. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 2 is characterized in that: The maximum depth of the arc-shaped groove is 500-800 mm.

5. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 2 is characterized in that: The depth of the anchoring borehole (1) is 6-15m.

6. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 1 is characterized in that: The structural detection of surrounding rocks at different depths of the tunnel floor includes: A detection borehole is constructed on the tunnel floor, the depth of the detection borehole is 15-20m; Ultrasonic detectors, strength meters and peep instruments are used to conduct all-round rock structure detection on the surrounding rocks at different depths of the bottom plate to determine the damage range, strength and joint and fissure distribution of the bottom plate surrounding rocks.

7. The method for reinforcing the soft rock tunnel floor with combined anchor bundles according to claim 1, characterized in that: The combined anchor cable comprises an anchor grouting anchor cable (3), a splitting grouting anchor cable (4) and a spare grouting anchor cable (5); the three anchor cables are all hollow structures; the anchor grouting anchor cable (3), the splitting grouting anchor cable (4) and the spare grouting anchor cable (5) are connected via a circular perforated support plate to form the combined anchor cable.

8. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 2 is characterized in that: The method further comprises: grouting the tunnel floor by means of a combined anchor cable, and pre-tensioning the combined anchor cable after grouting and anchoring; and then: Pouring concrete into the arc-shaped groove to fill it up and form a concrete inverted bottom arch (6); Two reserved grouting holes for later re-injection are constructed, and grouting iron pipes (7) are inserted to complete the hole sealing.

9. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 8, characterized in that: The spacing between the grouting holes is 2-3m, and the row spacing is 2-3m.

10. The soft rock tunnel floor combined anchor bundle reinforcement method according to claim 1, characterized in that: Also includes: A mobile monitoring base station is arranged on the tunnel floor to monitor the displacement of the tunnel floor in real time; A preload monitoring instrument is arranged at the tail of the combined anchor cable to monitor the stress condition of the anchor cable in real time during the mining process of the working face.

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