Anti-blasting and pressure-relief method for triangular isolated coal pillar formed by fault, flat roadway and crossheading cutting

Abstract

The present application belongs to the field of rock burst prevention and control of coal mine, and particularly relates to a method for preventing rock burst and pressure relief of a triangular isolated coal pillar formed by cutting of a fault, a gate road and a connecting road; the method comprises the following steps: reducing the elasticity and impact of the isolated coal pillar by constructing a large-diameter pressure relief borehole in the isolated coal pillar to achieve pressure relief of the isolated coal pillar; further reducing the isolated surface of the triangular coal pillar by filling the connecting road to prevent the coal body at the connecting road from being destabilized under the action of an advanced support pressure, and the filling rate is less than 100%, which can ensure that the connecting road continues to bear a part of the ventilation function; finally, solving the adverse effects of the triangular main roof above the isolated triangular coal pillar on the working face by cutting the roof to solve the adverse effects of the triangular main roof on the working face. The present application can fully relieve the pressure of the triangular isolated coal pillar, thereby ensuring the safety of the working face recovery, and effectively reducing the coal loss of the working face under the premise of ensuring safety, thereby increasing the coal recovery rate of the working face.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rock burst prevention and control in coal mines, and particularly relates to a rock burst prevention and pressure relief method for a triangular isolated coal pillar formed by cutting of a fault, a gate road and a crossheading. BACKGROUND

[0002] In recent years, with the increase of the mining depth of coal mines, the number of rock burst mines and the degree of rock burst danger have significantly increased, and the rock burst disaster risk of coal mines has sharply risen, which seriously affects the safety production of deep rock burst mines. Most of the rock burst accidents are related to fault structures. The fault structures are developed in the working face of a rock burst mine, and isolated coal pillars are easily formed by cutting of a fault, an upper and lower gate road and a crossheading. The isolated coal pillars are stress concentrated and greatly affected by mining, and are extremely prone to induce rock burst.

[0003] At present, two kinds of mining schemes are mainly adopted for the isolated coal pillars formed by cutting of a fault, an upper and lower gate road and a crossheading. One is to directly mine after pressure relief by large-diameter drilling in the upper and lower gate roads of the working face. The other is to leave a fault protective coal pillar and then mine after the working face is moved and a cut is re-excavated. The first scheme is insufficient in pressure relief of the isolated coal pillars, and there are many pressure relief blank zones. When the isolated coal pillars are affected by advanced mining, rock burst accidents are easily induced. The second scheme can avoid the occurrence of rock burst accidents, but the working face is moved and a cut is re-excavated, which wastes time and affects the mining efficiency. In addition, the left fault protective coal pillar cannot be mined, which causes waste of coal resources and reduces the coal mining rate of the working face.

[0004] Therefore, how to provide a new comprehensive rock burst prevention and pressure relief method to effectively solve the above technical problems is the content needed to be researched in the industry. SUMMARY

[0005] In order to solve the technical problem that the triangular isolated coal pillar formed by cutting of a fault, a gate road and a crossheading is prone to rock burst, the present application provides a rock burst prevention and pressure relief method for the triangular isolated coal pillar formed by cutting of a fault, a gate road and a crossheading. The applicable working condition is that a fault and a crossheading pass through the working face along the dip, and two isolated triangular coal pillars are formed by cutting of the fault, the upper gate road of the working face, the lower gate road of the working face and the crossheading. The method specifically comprises the following steps:

[0006] S1: determining the elastic energy required to be reduced by the triangular isolated coal pillar

[0007] The original elastic energy of the isolated coal pillar is obtained, the stress state when the working face passes through the isolated coal pillar is determined by numerical simulation, the elastic energy of the isolated coal pillar is reduced, the stress state when the working face passes through the isolated coal pillar after the elastic energy of the isolated coal pillar is reduced is determined by numerical simulation, and the stress state after the elastic energy of the isolated coal pillar is reduced is in a safe state.

[0008] S2: construction of large-diameter pressure relief borehole to isolated triangular coal pillar for pressure relief

[0009] Based on the required reduced elastic energy of the isolated coal pillar, parameters of the large-diameter pressure relief borehole are designed, the large-diameter pressure relief borehole is constructed from the connecting roadway to the isolated coal pillar, and the large-diameter pressure relief borehole is constructed to the fault position.

[0010] Preferably, in step S2, the construction direction of the large-diameter pressure relief borehole is perpendicular to the connecting roadway.

[0011] S3: filling of the connecting roadway

[0012] Based on the required reduced elastic energy of the isolated coal pillar, components of the filling material required for the connecting roadway and the filling rate are designed, so that the elastic energy of the connecting roadway after filling is consistent with the elastic energy of the triangular coal pillar after reduction; the connecting roadway is filled according to the designed components of the filling material and the filling rate, and the filling rate is not greater than 90%.

[0013] S4: cutting and pressure relief of the triangular main roof

[0014] The first main roof periodic weighting position and the last main roof periodic weighting position when the working face is mined to the fault range are calculated; the cutting borehole is constructed from the lower roadway to the triangular main roof formed by the first main roof periodic weighting position and the fault disc far from the cut; the triangular main roof is cut into multiple pieces through the cutting borehole; the cutting borehole is constructed from the upper roadway to the triangular main roof formed by the last main roof periodic weighting position and the fault disc close to the cut; and the triangular main roof is cut into multiple pieces through the cutting borehole.

[0015] S5: working face mining directly through the fault.

[0016] The beneficial technical effects of the present application are as follows: the present application can reduce the elastic energy of the isolated coal pillar by constructing a large-diameter pressure relief borehole, reduce the impact, and achieve pressure relief of the isolated coal pillar; further, the isolated surface of the triangular coal pillar can be reduced by filling the connecting roadway, the coal body at the connecting roadway can be prevented from being unstable under the action of the advanced support pressure, the filling rate is less than 100%, the connecting roadway can continue to bear part of the ventilation function, the last triangular main roof above the isolated triangular coal pillar is cut to solve the adverse effects of the triangular main roof on the working face production. The present application can fully relieve the pressure of the triangular isolated coal pillar, thereby ensuring the safety of the working face mining, effectively reducing the coal loss of the working face under the premise of ensuring safety, and thereby increasing the coal recovery rate of the working face. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a large-diameter pressure relief borehole construction plane schematic diagram of the triangular isolated coal pillar in the embodiment of the present application;

[0018] Figure 2This is a schematic diagram of the construction plan for filling the triangular isolated coal pillar connecting roadway in an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the drilling plan for cutting the top of a triangular isolated coal pillar in an embodiment of the present invention;

[0020] Figure 4 This is a schematic cross-sectional view of the upper level roadway during the construction of the triangular isolated coal pillar roof cutting borehole in an embodiment of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] Taking the 6305 working face of a certain mine as an example, the 6305 working face has a dip length of 260m, a burial depth of 900m, and a coal thickness of 5m. Figure 1 As shown, there is a fault F311 with a drop of 0-5m at a distance of 500m from the cut-off point. F311 is a normal fault. The side farther from the cut-off point is the footwall, which moves upward along the dip line of the fault plane. The side closer to the cut-off point is the hanging wall, which moves downward along the dip line of the fault plane. The intersection of F311 fault and the 6305 lower level roadway is closer to the cut-off point than the intersection with the 6305 upper level roadway. Due to the long advance distance of the 6305 working face, a 6305 connecting roadway was constructed at a distance of 500m from the cut-off point to facilitate ventilation, transportation, and other operations. The 6305 connecting roadway connects the 6305 upper level roadway and the 6305 lower level roadway. The intersection of the 5 connecting roadway and the 6305 upper level roadway is closer to the cut-off side than the intersection with the 6305 lower level roadway. The F311 fault intersects the 6305 connecting roadway within the working face, and the intersection point is closer to the middle of the working face. Thus, the F311 fault, the 6305 working face upper level roadway, the 6305 working face lower level roadway, and the connecting roadway cut together to form two isolated triangular coal pillars. Stress concentration at these isolated triangular coal pillars can easily lead to rockburst accidents. To address this problem, the present invention employs a rockburst prevention and pressure relief method for triangular isolated coal pillars formed by the cutting of faults, level roadways, and connecting roadways. The method includes the following steps:

[0023] S1: Determine the required reduction in elastic energy for a triangular isolated coal pillar.

[0024] The original elastic energy of the isolated coal pillar is obtained, and the stress state when the working face mines through the isolated coal pillar is determined by numerical simulation. The elastic energy of the isolated coal pillar is reduced, and the stress state when the working face mines through the isolated coal pillar after the elastic energy of the isolated coal pillar is reduced is determined by numerical simulation, so that the stress state of the isolated coal pillar after the elastic energy of the isolated coal pillar is reduced is in a safe state. The safe state can be obtained based on the stress state during the normal mining of the 6305 working face in the early stage (without faults or other special structures).

[0025] S2: Construction of large-diameter pressure relief boreholes to relieve pressure on isolated triangular coal pillars.

[0026] As shown in Figure 1 Based on the required reduced elastic energy of the isolated coal pillar, the parameters of the large-diameter pressure relief borehole, including the hole diameter, spacing and row spacing, are designed; the large-diameter pressure relief borehole is constructed from the 6305 connecting roadway to the isolated coal pillar, and the terminal hole of the large-diameter pressure relief borehole is constructed to the fault position.

[0027] In this embodiment, one row of large-diameter pressure relief boreholes is constructed, the spacing is 1m, the hole diameter is 150mm, and the construction direction is perpendicular to the 6305 connecting roadway.

[0028] S3: filling the connecting roadway

[0029] As shown in Figure 2 Based on the required reduced elastic energy of the isolated coal pillar, the required filling material components and filling rate of the 6305 connecting roadway are designed, so that the elastic energy after filling the connecting roadway is consistent with the reduced elastic energy of the triangular coal pillar; the intersection of the 6305 lower roadway and the 6305 connecting roadway is closed, and the 6305 connecting roadway is filled according to the designed filling material components and filling rate; after filling is completed, the closure of the intersection of the 6305 lower roadway and the 6305 connecting roadway is opened.

[0030] In this embodiment, the components of the filling material by mass are: coal 35%, cement 30%, fly ash 35%; the water-solid mass ratio is 0.8; and the filling rate is 90%.

[0031] In the present application, filling the connecting roadway can reduce the isolated surface of the triangular coal pillar, prevent the coal body at the connecting roadway from being unstable under the action of the advanced support pressure, and ensure that the connecting roadway continues to bear part of the ventilation function when the filling rate is less than 100%.

[0032] S4: cutting the top of the triangular main roof to release pressure

[0033] As shown in Figures 3-4 The first main roof periodic weighting position and the last main roof periodic weighting position when the working face is mined to the F311 fault range are calculated; the cutting top borehole is constructed from the 6305 lower roadway to the triangular main roof formed by the first main roof periodic weighting position and the lower wall of the F311 fault (the fault wall far from the cut); the triangular main roof is cut into multiple pieces through the cutting top borehole; the cutting top borehole is constructed from the 6305 upper roadway to the triangular main roof formed by the last main roof periodic weighting position and the upper wall of the F311 fault (the fault wall close to the cut); and the triangular main roof is cut into multiple pieces through the cutting top borehole.

[0034] S5: the working face directly mines through the F311 fault without needing to skip mining.

[0035] For the basic roof directly above the isolated triangular coal pillar, the intersection of the fault and the roadway is also triangular, and the breaking position and movement law of the basic roof at the triangular basic roof are difficult to obtain; and when the working face directly advances through the fault, the breaking positions of the basic roof on both sides of the fault are easy to be inconsistent, which is not conducive to the safety production of the working face, and the influence of the triangular basic roof on the production of the working face is solved by cutting the roof.

[0036] Of course, the above description is only for the preferred embodiments of the present application, and the present application is not limited to the above-described embodiments. It should be noted that any equivalent replacement and obvious deformation made by any person skilled in the art under the guidance of the present application shall fall within the scope of the present application, and shall be protected by the present application.

Claims

1. A method for preventing bumping and pressure relief of a triangular isolated coal pillar formed by cutting of a fault, gateways and crossheading, suitable working conditions are: there is a fault and a crossheading passing through the working face along the tendency in the working face, and two triangular isolated coal pillars are formed by cutting of the fault, the upper gateway of the working face, the lower gateway of the working face and the crossheading, characterized in that, The method comprises the following steps: S1: determining the elastic energy required to be reduced for the triangular isolated coal pillar Obtaining the original elastic energy of the isolated coal pillar, determining the stress state when the working face passes through the isolated coal pillar through numerical simulation, reducing the elastic energy of the isolated coal pillar, and determining the stress state when the working face passes through the isolated coal pillar after the elastic energy of the isolated coal pillar is reduced through numerical simulation, so that the stress state of the isolated coal pillar after the elastic energy is reduced is in a safe state; S2: constructing large-diameter pressure relief boreholes for pressure relief of the triangular isolated coal pillar Based on the elastic energy required to be reduced for the isolated coal pillar, the parameters of the large-diameter pressure relief borehole are designed, the large-diameter pressure relief borehole is constructed from the connecting roadway to the isolated coal pillar, and the large-diameter pressure relief borehole is constructed to the fault position; S3: filling the connecting roadway Based on the elastic energy required to be reduced for the isolated coal pillar, the filling material components and the filling rate required for the connecting roadway are designed, so that the elastic energy of the connecting roadway after filling is consistent with that of the triangular isolated coal pillar after the elastic energy is reduced; The connecting roadway is filled according to the designed filling material components and the filling rate, and the filling rate is not greater than 90%; S4: cutting the triangular main roof for pressure relief The first main roof periodic weighting position and the last main roof periodic weighting position when the working face is mined to the fault range are calculated, the cutting borehole is constructed from the lower roadway to the triangular main roof formed by the first main roof periodic weighting position and the fault disc far from the cut hole, the triangular main roof is cut into multiple pieces through the cutting borehole, the cutting borehole is constructed from the upper roadway to the triangular main roof formed by the last main roof periodic weighting position and the fault disc close to the cut hole, and the triangular main roof is cut into multiple pieces through the cutting borehole; S5: the working face directly passes through the fault.

2. The method of claim 1, wherein, In step S2, the construction direction of the large-diameter pressure relief borehole is perpendicular to the connecting roadway.

Images