A full-process control method for a roadway passing under a goaf in sections

Abstract

The present invention discloses a method for the whole-process control of a roadway passing under a goaf in sections. The characteristics are as follows: detecting the size and position of the roof cavity in front of the roadway by using a ground-penetrating radar and a three-dimensional borehole detector, driving grouting pipes to grout the cavity in the goaf in front to ensure the stability during the roadway driving process. After the roadway is driven, using resistance-increasing and yielding grouting anchor cables to support the roof and conduct secondary grouting to ensure the stability of the roadway passing under the goaf. Monitoring the stress value of the grouting pipe, the change of cracks after grouting, and the yielding amount of the resistance-increasing and yielding grouting anchor cables, respectively calculating the average stress rate of the grouting pipe, the change rate of the yielding amount of the resistance-increasing and yielding grouting anchor cables, and the filling rate of the roof cracks, establishing a comprehensive evaluation value for the roadway passing under the goaf to evaluate the stability of the roadway passing under the goaf. When the roadway passing under the goaf is in a stable state, the roadway can carry out the next cycle of driving.

Description

Technical Field

[0001] The present invention relates to the technical field of underground engineering safety, and more specifically, to a method for full-process control of a roadway passing through a goaf in a divided manner. Background Art

[0002] Coal resources are the pillar energy source. However, years of coal mining have led to the depletion of shallow coal resources. After the upper coal layer is mined, the lower coal layer can be mined to solve the problem of insufficient coal mining reserves, achieving the purpose of reducing waste of coal resources and extending the production time of the mine.

[0003] Since a goaf is formed after the upper coal layer is mined, after the overlying rock strata collapse, the loose and broken gangue fills the goaf. When driving a roadway in the lower coal layer, the roof of the roadway is the goaf, resulting in the falling of broken rocks on the roof of the roadway, the sinking of the roof, and in severe cases, large-scale roof falls. There is no stable anchoring point for bolts (cables), and the support members cannot exert their support capacity, seriously affecting the stability of the roadway passing through the goaf. Therefore, it is very necessary to carry out full-process control of the roadway passing through the goaf in a divided manner to ensure the safety of the roadway passing through the goaf.

[0004] The existing technologies have the following problems:

[0005] 1. Before roadway driving, the goaf in the front roof cannot be effectively controlled;

[0006] 2. After roadway driving, a feasible treatment for the goaf in the roof of the roadway cannot be carried out. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies of the above-mentioned existing technologies, and provide a method for full-process control of a roadway passing through a goaf in a divided manner.

[0008] The technical solution provided by the present invention is: a method for full-process control of a roadway passing through a goaf in a divided manner, which is characterized in that it includes the following steps:

[0009] a Detect the goaf in the front roof of the roadway to determine the cavity position and volume of the goaf in the front roof of the roadway;

[0010] b Drill grouting holes in the cavity of the goaf, install grouting pipes, grout the cavity in the front upper part of the goaf, and use resistance-increasing and yielding fixed grouting cables and steel belts to fix the grouting pipes;

[0011] c Excavate the roadway passing through the goaf, support the roof of the roadway with bolt-net-shotcrete, grout the roof of the roadway with resistance-increasing and yielding grouting cables, and perform secondary grouting to reinforce the roof of the goaf of the roadway;

[0012] Collect the stress of the grouting pipe, obtain the number of roof fissures in the goaf before and after grouting, monitor the yielding amount of the yielding and resistance-increasing grouting cable bolt, calculate the average stress rate of the grouting pipe, the filling rate of the roof fissures, and the average change rate of the yielding amount of the yielding and resistance-increasing grouting cable bolt;

[0013] e Use the weight analysis method to establish a comprehensive evaluation value of the stability of the roadway passing through the goaf, analyze the stability of the roadway passing through the goaf, and when the stability of the roadway passing through the goaf is evaluated, the roadway proceeds to the next cycle of tunneling.

[0014] Preferably, in step a, detecting the goaf in the roof above the roadway uses radar to detect the cavity position of the goaf in the roof above the roadway; determining the volume of the goaf in the roof above the roadway is to drill holes in the roadway cavity to determine the distance L between the cavity and the tunneling face, and use the cavity drilling three-dimensional measurement system to measure the volume V of the goaf cavity in the roof.

[0015] Preferably, in step b, grouting holes are drilled in the goaf cavity, a grouting pipe is installed, a reverse barrier is provided at the front end of the grouting pipe, the reverse barrier is embedded in the inner wall of the cavity to prevent the reverse ejection of the grouting pipe, the length of the grouting pipe is L, and the goaf cavity in the roof of the roadway is grouted in advance. The volume of the grouting slurry is greater than the volume V of the cavity to ensure that the goaf cavity is filled densely.

[0016] Preferably, in step b, installing the grouting pipe is to drive the grouting pipe from the upper end of the tunneling face of the roadway passing through the goaf into the roof surrounding rock to grout the front roof. The end of the grouting pipe is fixed by a steel strip. The steel strip is provided with installation holes and is fixed to the roof by the yielding and resistance-increasing fixed grouting cable bolt to realize the fixed constraint on the grouting pipe.

[0017] Preferably, in step b, a stress gauge is fixedly connected to the inner wall of the grouting pipe, the stress gauge and the acquisition line are protected by colloid, and the stress of the grouting pipe is monitored in real time by the stress gauge.

[0018] Preferably, in step c, the tunneling step of the roadway passing through the goaf is 2 / 3L, and the yielding and resistance-increasing grouting cable bolt is used to support and grout the roof of the roadway. The yielding and resistance-increasing grouting cable bolt is inserted and driven in the middle of the grouting pipe to perform secondary grouting on the roof surrounding rock of the roadway.

[0019] Preferably, in step d, detection holes are drilled in the roadway passing through the goaf to detect the initial number of fissures m1 in the roof surrounding rock of the roadway, the number of fissures m2 in the roof surrounding rock after the advance grouting of the roof of the roadway, and the number of fissures m3 in the roof surrounding rock after the secondary grouting of the grouting cable bolt;

[0020] The average stress rate of the grouting pipe is F = (ε1 - ε0) / nε0, where ε1 is the current stress of the grouting pipe, ε0 is the stress of the grouting pipe at the previous monitoring moment, and n is the number of all current stress gauges of the grouting pipe;

[0021] The average change rate of the yielding amount of the resistance - increasing and yielding - pressure - releasing grouting cable bolt is S = (s1 - s0) / zs0, where s1 is the current yielding amount of the resistance - increasing and yielding - pressure - releasing grouting cable bolt, s0 is the yielding amount of the resistance - increasing and yielding - pressure - releasing grouting cable bolt at the previous monitoring moment, and z is the number of resistance - increasing and yielding - pressure - releasing grouting cable bolts in the current roadway driving section;

[0022] The filling rate of the roof fissures of the roadway is M = (m1 - m2 - m3) / m1.

[0023] Preferably, the comprehensive evaluation value of the stability of the roadway passing under the goaf in step e is R1 = FB1 + SB2 + MB3, where Bi is the correlation coefficient, B1 + B2 + B3 = 1, the range of B1 is 0.2 - 0.3, the range of B2 is 0.3 - 0.4, and the range of B3 is 0.3 - 0.4.

[0024] The beneficial effects of the present invention:

[0025] 1. Adopting a step - by - step and whole - process method to control the surrounding rock of the roadway passing under the goaf, pre - grouting the surrounding rock in front of the roadway by using a grouting pipe, and performing secondary grouting control on the surrounding rock of the roadway by using the resistance - increasing and yielding - pressure - releasing grouting cable bolt to ensure the stability of the surrounding rock of the roadway;

[0026] 2. Considering the average stress rate of the grouting pipe, the filling rate of the roof fissures and the average change rate of the yielding amount of the resistance - increasing and yielding - pressure - releasing grouting cable bolt, comprehensively evaluating the stability of the roadway passing under the goaf, and ensuring the safety during the driving process and the service process of the roadway passing under the goaf. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the flow chart of the present invention;

[0028] Figure 2 is the structural schematic diagram of the present invention;

[0029] Figure 3 is the structural schematic diagram of the grouting pipe of the present invention;

[0030] Figure 4 is the enlarged structural schematic diagram of the reverse barrier of the grouting pipe of the present invention.

[0031] In the figure: 1 grouting pipe, 2 resistance - increasing and yielding - pressure - releasing fixed grouting cable bolt, 3 resistance - increasing and yielding - pressure - releasing grouting cable bolt, 4 steel strip, 5 stress gauge, 6 spring, 7 roadway, 8 goaf, 9 cavity, 10 reverse barrier. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The present invention will be described in detail below with reference to the accompanying drawings.

[0033] As shown in Figure 1 、 2 、3, 4, a step - by - step and whole - process control method for a roadway passing under a goaf specifically includes the following steps:

[0034] First step: Use radar to detect the approximate position and size of the cavity in the goaf above the roof at the roadway driving face. Use a drill rig to drill holes in the largest cavity within the driving footage range to determine the distance L between the cavity and the driving face. Use the cavity drilling three-dimensional measurement system to measure the volume V of the cavity in the roof goaf;

[0035] Second step: Drill grouting holes in the goaf, install the grouting pipe 1, set a reverse barrier device 10 at the front end of the grouting pipe 1, install a spring 6 on the reverse barrier device 10. During the installation of the grouting pipe 1, the reverse barrier device 10 is in a closed state. When the front end of the grouting pipe 1 reaches the cavity, the reverse barrier device 10 opens under the action of the spring 6, and the reverse barrier device 10 is embedded in the inner wall of the cavity 9 to prevent the reverse ejection of the grouting pipe 1. The length of the grouting pipe 1 is L. Conduct advanced grouting on the roof goaf 8 of the roadway 7, and the volume of the grouting slurry is greater than the volume V of the cavity to ensure that the cavity 9 in the goaf 8 is filled densely;

[0036] Drive the grouting pipe 1 from the upper end of the driving face of the roadway 7 passing through the goaf to the roof surrounding rock, grout the front roof, fix the end of the grouting pipe 1 with a steel strip 4, set installation holes on the steel strip 4, and fix it to the roof by the resistance increasing and yielding fixed grouting anchor cable 2 to achieve the fixed constraint on the grouting pipe 1;

[0037] Weld a stress gauge 5 on the inner wall of the grouting pipe 1. The stress gauges 5 are evenly distributed on the inner wall of the grouting pipe 1. Protect the stress gauges 5 and the acquisition lines with colloid, and use the stress gauges 5 to monitor the stress value of the grouting pipe 1 in real time;

[0038] Third step: Excavate the roadway 7 passing through the goaf. The roadway 7 passing through the goaf is driven, and the driving step distance is 2 / 3L. Use the resistance increasing and yielding grouting anchor cable 3 to support and grout the roof of the roadway. The resistance increasing and yielding grouting anchor cable 3 is inserted and drilled in the middle of the grouting pipe 1. The row spacing of the resistance increasing and yielding grouting anchor cable 3 along the longitudinal direction of the roadway is 1.5 times the diffusion distance of the slurry, and the slurry conducts secondary grouting on the roof surrounding rock of the roadway;

[0039] Fourth step: Collect the stress of the grouting pipe 1, obtain the number of roof fissures in the goaf 8 before and after grouting, monitor the yielding amount of the resistance increasing and yielding grouting anchor cable 3, and calculate the average stress rate of the grouting pipe 1, the roof fissure filling rate, and the average change rate of the yielding amount of the resistance increasing and yielding grouting anchor cable 3;

[0040] Drill detection holes in the roadway passing through the goaf to detect the initial number of fissures m1 in the roof surrounding rock of the roadway, the number of fissures m2 in the surrounding rock after the advanced grouting of the roof of the roadway, and the number of fissures m3 in the surrounding rock after the secondary grouting of the resistance increasing and yielding grouting anchor cable;

[0041] The average stress rate of the grouting pipe is F = (ε1 - ε0) / nε0, where ε1 is the current stress of the grouting pipe, ε0 is the stress of the grouting pipe at the previous monitoring time, and n is the number of stress gauges of the grouting pipe currently used;

[0042] The average change rate of the yielding amount of the resistance-increasing and yielding-pressure-relieving grouting cable bolt is S = (s1 - s0) / zs 0， s1 is the yielding amount of the resistance-increasing and yielding-pressure-relieving grouting cable bolt currently, s0 is the yielding amount of the resistance-increasing and yielding-pressure-relieving grouting cable bolt at the previous monitoring time, and z is the number of resistance-increasing and yielding-pressure-relieving grouting cable bolts in the current roadway driving section;

[0043] The crack filling rate of the roadway roof is M = (m1 - m2 - m3) / m1;

[0044] In the fifth step, using the weight analysis method, establish the comprehensive evaluation value of the stability of the roadway passing under the goaf. The comprehensive evaluation value of the stability of the roadway passing under the goaf is R1 = FB1 + SB2 + MB3, where B i is the correlation coefficient, B1 + B2 + B3 = 1, the range of B1 is 0.2 - 0.3, the range of B2 is 0.3 - 0.4, and the range of B3 is 0.3 - 0.4. According to the degree of surrounding rock fragmentation and the magnitude of in-situ stress on site, select appropriate coefficients, and compare the value of R1 with the statistical standard value R0 of the evaluation effect of the stability of the cross-cut roadway. When R 1≤ ≥ R0, it means that the current roadway passing under the goaf is in a stable state, and the roadway can carry out the next cycle of driving.

[0045] As is known from technical common sense, the present invention can be implemented by other embodiments that do not depart from its essence or essential features. Therefore, in all aspects, it is only an example and not the only one. All changes within the scope of the present invention or within the scope equivalent to the present invention are encompassed by the present invention.

Claims

1. A method for controlling the entire process of a tunnel section under a goaf, characterized in that: The following steps are involved: a. Detect the goaf of the roof above the front of the roadway to determine the position and volume of the cavity in the goaf of the roof above the front of the roadway; b. Drill grouting holes in the cavity of the goaf, install grouting pipes, grout the cavity above the front of the goaf, and use resistance-enhancing pressure to fix the grouting anchor cables and steel belts to fix the grouting pipes; c. Excavate a tunnel under the goaf, use anchor mesh spraying to support the tunnel roof, use resistance-enhancing pressure-relieving grouting anchor cables to grout the tunnel roof, and then reinforce the goaf roof with secondary grouting; d. Collect grouting pipe stress, obtain the number of roof cracks in the goaf before and after grouting, monitor the pressure relief of the resistance-enhancing pressure-relieving grouting anchor cables, and calculate the average stress rate of the grouting pipe, the roof crack filling rate, and the average change rate of the pressure relief of the resistance-enhancing pressure-relieving grouting anchor cables; e. Using the weight analysis method, establish a comprehensive evaluation value of the stability of the roadway under the goaf, analyze the stability of the roadway under the goaf, and when the roadway under the goaf is evaluated to be stable, the roadway will proceed to the next cycle of excavation; In step d, detection holes are drilled in the tunnel passing through the goaf to detect the number of initial cracks in the tunnel roof m1, the number of cracks in the tunnel roof after pre-grouting m2, and the number of cracks in the tunnel roof after secondary grouting of the grouting anchor cable m3; The average stress rate of the grouting pipe is F=(ε1-ε0) / nε0, ε1 is the current grouting pipe stress, ε0 is the grouting pipe stress at the previous monitoring moment, and n is the number of all current grouting pipe stress gauges; The average change rate of the resistance-enhancing pressure-yielding grouting anchor cable pressure relief amount is S=(s1-s0) / zs0, where s1 is the current resistance-enhancing pressure-yielding grouting anchor cable pressure relief amount, s0 is the resistance-enhancing pressure-yielding grouting anchor cable pressure relief amount at the previous monitoring moment, and z is the number of resistance-enhancing pressure-yielding grouting anchor cables in the current tunnel excavation section; The tunnel roof crack filling rate is M= (m1-m2-m3) / m1.

2. A method for controlling the entire process of a tunnel passing through a goaf according to claim 1, characterized in that: The detection of the goaf in the top plate above the front of the tunnel in step a is to use radar to detect the position of the cavity in the goaf in the top plate above the front of the tunnel; the determination of the volume of the goaf in the top plate above the front of the tunnel is to drill holes in the tunnel cavity, determine the distance L between the cavity and the excavation working face, and use a cavity drilling three-dimensional measurement system to measure the volume V of the cavity in the top plate goaf.

3. The method for controlling the entire process of a tunnel passing through a goaf according to claim 1 is characterized in that: The step b is to drill grouting holes in the goaf cavity, install a grouting pipe, set a reverse blocker at the front end of the grouting pipe, embed the reverse blocker into the inner wall of the cavity to prevent the grouting pipe from spraying out in the reverse direction. The length of the grouting pipe is L, and the cavity in the goaf of the tunnel roof is grouted in advance. The volume of the grouting slurry is greater than the volume V of the cavity to ensure that the goaf cavity is filled densely.

4. The method for controlling the entire process of a tunnel passing through a goaf according to claim 1 is characterized in that: The installation of the grouting pipe in step b is to inject the grouting pipe into the roof surrounding rock from the upper end of the tunnel excavation working face under the goaf, and grout the front roof. The end of the grouting pipe is fixed with a steel belt, and the steel belt is provided with an installation hole. The grouting anchor cable is fixed to the roof by increasing resistance and pressure to achieve fixed constraint of the grouting pipe.

5. The method for controlling the entire process of a tunnel passing through a goaf according to claim 1, characterized in that: In the step b, a stress gauge is fixed to the inner wall of the grouting pipe, the stress gauge and the acquisition line are protected by colloid, and the stress gauge is used to monitor the stress of the grouting pipe in real time.

6. The method for controlling the entire process of a tunnel passing through a goaf according to claim 1, characterized in that: In the step c, the tunnel excavation distance under the goaf is 2 / 3L, and the tunnel roof is supported and grouted by using the resistance-enhancing pressure-relieving grouting anchor cable. The resistance-enhancing pressure-relieving grouting anchor cable is inserted and injected in the middle of the grouting pipe, and the tunnel roof surrounding rock is grouted twice.

7. The method for controlling the entire process of a tunnel passing through a goaf according to claim 1, characterized in that: The comprehensive evaluation value of the stability of the tunnel under the goaf established in step e is R1=FB1+SB2+MB3, Bi is the correlation coefficient, B1+B2+B3=1, B1 ranges from 0.2-0.3, B2 ranges from 0.3-0.4, and B3 ranges from 0.3-0.4.

Images