阅读说明：本技术 一种针对连续多层坚硬顶板煤层的高低位断顶卸压方法 (High-low top-breaking pressure relief method for continuous multi-layer hard roof coal seam ) 是由 董近兴 郭晓胜 吕卫东 宋士康 司雷 张涛 任康江 刘鹏 于 2021-09-15 设计创作，主要内容包括：本发明属于煤炭开采技术领域,具体公开了一种针对连续多层坚硬顶板煤层的高低位断顶卸压方法,包括利用关键层理论,计算出具有可压裂性的多个预地面压裂岩层,确定断顶层位；根据断顶层位和钻机施工能力设计钻孔倾角、孔深,分别从回风顺槽和运输顺槽向断顶层位钻孔；合理组织顶板爆破孔施工,保证断顶工程超前工作面不少于采动影响范围,降低施工期间的冲击威胁；合理选择装药爆破时机,同组扇形孔同时起爆；通过微震法或钻屑法对施工范围开展效果检验。本发明在一定程度上解决了多层坚硬顶板关键层的冲击地压煤层安全开采的问题,具有一定的创新性和推广应用价值,同时具有显著的社会效益。(The invention belongs to the technical field of coal mining, and particularly discloses a high-low top breaking pressure relief method for a continuous multilayer hard roof coal seam, which comprises the steps of calculating a plurality of pre-ground fractured rock layers with the capability of fracturing by utilizing a key layer theory, and determining a top breaking layer position; designing a drill hole inclination angle and a hole depth according to the broken top layer position and the construction capacity of the drilling machine, and drilling holes from the return air gateway and the transportation gateway to the broken top layer position respectively; the roof blast hole construction is reasonably organized, the advance working face of the broken roof engineering is not less than the mining influence range, and the impact threat during the construction period is reduced; the charging blasting time is reasonably selected, and the same group of fan-shaped holes are detonated simultaneously; and carrying out effect inspection on the construction range by a micro-seismic method or a drilling cutting method. The invention solves the problem of safe exploitation of rock burst coal seams of key layers of a plurality of layers of hard top plates to a certain extent, has certain innovativeness and popularization and application values, and has remarkable social benefits.)

1. A high-low top breaking pressure relief method for continuous multilayer hard roof coal seams is characterized by comprising the following steps:

step 1: calculating a plurality of pre-ground fractured rock layers with the fracturing performance by utilizing a key layer theory, and determining a top fracture level;

step 2: designing a drill hole inclination angle and a hole depth according to the broken top layer position and the construction capacity of the drilling machine, and drilling holes from the return air gateway and the transportation gateway to the broken top layer position respectively;

and step 3: the roof blast hole construction is reasonably organized, the advance working face of the broken roof engineering is not less than the mining influence range, and the impact threat during the construction period is reduced;

and 4, step 4: the charging blasting time is reasonably selected, and the same group of fan-shaped holes are detonated simultaneously;

and 5: and carrying out effect inspection on the construction range by a micro-seismic method or a drilling cutting method.

2. The method for high-low top-breaking pressure relief of the continuous multilayer hard roof coal seam according to claim 1, wherein the residual energy transferred to the working face coal seam from the plurality of pre-ground fractured rock formations is calculated by utilizing rock formation release energy attenuation characteristics.

3. The high-low top-off pressure relief method for the continuous multilayer hard roof coal seam according to claim 2, wherein in the step 2, the top-off level comprises a coarse sand layer, a medium sand layer, a fine sand layer and a mudstone layer, the layer thickness of the coarse sand layer is 20.08m, the layer thickness of the medium sand layer is 13.03m, the layer thickness of the fine sand layer is 10.79m, and the layer thickness of the mudstone layer is 1.25 m.

4. The method for high-low top-off pressure relief for continuous multilayer hard roof coal seams according to claim 3, wherein the inclination angle of the fine sand formation is 40 °, the inclination angle of the medium sand formation is 50 °, and the inclination angle of the coarse sand formation is 60 °.

5. The method for high-low top-breaking pressure relief of the continuous multilayer hard roof coal seam according to claim 4, wherein the drill holes respectively penetrate through the top-breaking layer.

6. The method for high-low top-breaking pressure relief of the continuous multi-layer hard roof coal seam as claimed in claim 5, wherein the air return gate and the transportation gate are drilled according to the inclination angles respectively, and the number of the drilled holes is 6, so that fan-shaped holes are formed.

7. The method for high-low top-breaking pressure relief of the continuous multilayer hard roof coal seam as claimed in claim 1, wherein the blasting depth is determined according to the principle of deep stress concentration region, and the blasting range is determined in the stress concentration region: determining the hole distance according to the widths of the crushing zone and the cracking zone to ensure that the crushing zones of two adjacent blast holes are communicated; the charge length of each bore is 1/3-1/2 of the bore depth.

8. The high-low top-breaking pressure relief method for the continuous multilayer hard roof coal seam according to claim 7, characterized in that the blasting mode adopts millisecond detonator grouping blasting.

9. The method for high-low top-breaking pressure relief of the continuous multilayer hard roof coal seam according to claim 8, wherein the same group of fan-shaped holes are detonated simultaneously during blasting.

10. The high-low top-breaking pressure relief method for the continuous multilayer hard roof coal seam according to claim 9, wherein the microseismic method is used for accurately calculating the position and energy of a seismic source, and the drilling cutting method is used for determining the stress state of surrounding rocks of a roadway through measurement of the amount of pulverized coal.

Technical Field

The invention belongs to the technical field of coal mining, and particularly relates to a high-low top-breaking pressure relief method for continuous multi-layer hard roof coal seams.

Background

In recent years, with the annual increase of coal mining depth in China, the problem of ore pressure impact in a plurality of mining areas becomes more and more serious, and a part of factors causing the problem is that a top plate of a goaf is too hard and is difficult to collapse. If the hard roof can not be subjected to timely pressure relief treatment in the coal mining process, a large-area suspended roof is extremely easy to form, and once the suspended roof is broken, a roadway can be instantly damaged, so that the coal mine safety is seriously threatened.

However, because the hard roof is far away from the coal seam, the thickness is large, the treatment difficulty is great, the investment cost is high, the pressure relief measures adopted at present, such as roof blasting and hydraulic fracturing, are all located in a roadway and a chamber under a coal mine, the construction site can only carry out local pre-fracturing on the low roof rock stratum within a small range, and for the high-position thick-layer hard roof, the method is difficult to realize large-range treatment, which is one of important reasons for causing frequent occurrence of rock burst accidents.

Therefore, it is an urgent technical problem to be solved by those skilled in the art to provide a method for high-low top-breaking pressure relief of continuous multi-layer hard roof coal seam.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a high-low top breaking pressure relief method for continuous multi-layer hard roof coal seams.

The invention provides a high-low top-breaking pressure relief method for continuous multilayer hard roof coal seams, which comprises the following steps of:

step 1: calculating a plurality of pre-ground fractured rock layers with the fracturing performance by utilizing a key layer theory, and determining a top fracture level;

step 2: designing a drill hole inclination angle and a hole depth according to the broken top layer position and the construction capacity of the drilling machine, and drilling holes from the return air gateway and the transportation gateway to the broken top layer position respectively;

and step 3: the roof blast hole construction is reasonably organized, the advance working face of the broken roof engineering is not less than the mining influence range, and the impact threat during the construction period is reduced;

and 4, step 4: the charging blasting time is reasonably selected, and the same group of fan-shaped holes are detonated simultaneously;

and 5: and carrying out effect inspection on the construction range by a micro-seismic method or a drilling cutting method.

According to the multiple pre-ground fractured rock formations, the remaining energy transmitted to the coal bed of the working face by the multiple pre-ground fractured rock formations is calculated by utilizing rock formation release energy attenuation characteristics.

In a further scheme, in the step 2, the top fracture layer comprises a coarse-grained sandstone layer, a medium-grained sandstone layer, a fine-grained sandstone layer and a mudstone layer, wherein the layer thickness of the coarse-grained sandstone layer is 20.08m, the layer thickness of the medium-grained sandstone layer is 13.03m, the layer thickness of the fine-grained sandstone layer is 10.79m, and the layer thickness of the mudstone layer is 1.25 m.

In a further scheme, the inclination angle of the fine sand stratum is 40 degrees, the inclination angle of the medium sand stratum is 50 degrees, and the inclination angle of the coarse sand stratum is 60 degrees.

The further scheme is that the drill holes respectively penetrate through the top breaking layer position.

The further scheme is that holes are drilled in the return air gate way and the transportation gate way respectively according to the inclination angles, and the number of the drilled holes is 6, so that fan-shaped holes are formed.

The further scheme is that the determination of the blasting depth is in accordance with the principle of going deep into the stress concentration area, and the blasting range is in the stress concentration area: determining the hole distance according to the widths of the crushing zone and the cracking zone to ensure that the crushing zones of two adjacent blast holes are communicated; the charge length of each bore is 1/3-1/2 of the bore depth.

The further scheme is that the blasting mode adopts millisecond detonator grouping blasting.

The further scheme is that the same group of fan-shaped holes are detonated simultaneously during blasting.

The method is characterized in that the microseismic method is used for accurately calculating the position and the energy of a seismic source, and the drilling cutting method is used for determining the stress state of the surrounding rock of the roadway through the measurement of the coal dust amount.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention solves the problem of safe exploitation of rock burst coal seams of key layers of a plurality of layers of hard top plates to a certain extent, has certain innovativeness and popularization and application values, and has remarkable social benefits.

(2) The hard top plate is processed in a high-low top plate pre-splitting blasting hole mode, the top breaking effect can be effectively enhanced, the periodic pressure step distance during the working face pushing and collecting period is controlled, and safe production is realized.

Drawings

The invention is illustrated and described only by way of example and not by way of limitation in the scope of the invention as set forth in the following drawings, in which:

FIG. 1: the invention relates to a flow chart of a high-low top-breaking pressure relief method;

FIG. 2: and the high-low top-breaking presplitting blasting drilling hole arrangement schematic diagram.

Detailed Description

In order to make the objects, technical solutions, design methods, and advantages of the present invention more apparent, the present invention will be further described in detail by specific embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, the invention provides a high-low top-breaking pressure relief method for continuous multilayer hard roof coal seams, which comprises the following steps:

step 1: calculating a plurality of pre-ground fractured rock layers with the fracturing performance by utilizing a key layer theory, and determining a top fracture level;

step 2: designing a drill hole inclination angle and a hole depth according to the broken top layer position and the construction capacity of the drilling machine, and drilling holes from the return air gateway and the transportation gateway to the broken top layer position respectively;

and step 3: the roof blast hole construction is reasonably organized, the advance working face of the broken roof engineering is not less than the mining influence range, and the impact threat during the construction period is reduced;

and 4, step 4: the charging blasting time is reasonably selected, and the same group of fan-shaped holes are detonated simultaneously;

and 5: and carrying out effect inspection on the construction range by a micro-seismic method or a drilling cutting method.

Specifically, the heights of a caving zone, a fracture zone and a bending subsidence zone of coal mining are calculated according to mine geological data, a target rock stratum needing modification and pressure relief is determined in the height range of the fracture zone by comparing with a typical drilling histogram, and then the remaining energy transmitted to a working face coal seam from the plurality of pre-ground fractured rock strata is calculated according to the plurality of pre-ground fractured rock strata and by utilizing rock stratum release energy attenuation characteristics.

In this embodiment, the coal seam mined in the coal mine is 4# coal, and the 4# coal seam is judged to belong to class iii and to be a coal seam with strong impact tendency according to the national standard GB/T25217.2-2010 "determination method for impact tendency classification and index of coal" by the beijing coalyard rock mechanics laboratory according to the data determined by the coal sample to be inspected; the top and bottom floor strata belong to the category II and are the top and bottom floor strata with weak impact tendency. At present, a mine is developed to a three-disk area, the geological conditions of the three-disk area are greatly changed compared with a first disk area and a second disk area, and the three-disk area is mainly characterized in that a continuous 3-layer hard sandstone key layer with the single-layer thickness of more than 10m is formed above a coal seam, the stress concentration degree of a stope face and two crossheading layers can be effectively weakened through top breaking treatment of the key layer, and the impact risk is reduced.

As shown in fig. 2, in step 2, the broken top layer comprises a coarse sand layer, a medium sand layer, a fine sand layer and a mudstone layer, wherein the layer thickness of the coarse sand layer is 20.08m, the layer thickness of the medium sand layer is 13.03m, the layer thickness of the fine sand layer is 10.79m, the layer thickness of the mudstone layer is 1.25m, the inclination angle of the fine sand layer is 40 °, the inclination angle of the medium sand layer is 50 °, the inclination angle of the coarse sand layer is 60 °, and the drill holes respectively penetrate through the broken top layer. As can be seen from FIG. 2, the drill hole length of the fine sand formation is 10.79/Sin40 DEG and about 16.78m, the drill hole length of the medium sand formation is 13.3/Sin50 DEG and about 17.36m, and the drill hole length of the coarse sand formation is 20.08/Sin60 DEG and about 23.18 m. The blasting long drill hole is used for cutting off the propagation path of the top plate high-position advanced bearing pressure, and the blasting short drill hole is used for cutting off the propagation path of the top plate low-position advanced bearing pressure, so that a main roadway near a mining area is free from the influence of the display of mining pressure, the stress environment of surrounding rock of the roadway is improved, and the deformation of the roadway is weakened.

Optionally, the air return gate and the transportation gate are drilled with 6 holes according to the inclination angles, so that fan-shaped holes are formed, and the purpose of enhancing the blasting effect is achieved.

Optionally, the determination of the blasting depth should be in accordance with the principle of going deep into the stress concentration region, and the blasting range should be in the stress concentration region: determining the hole distance according to the widths of the crushing zone and the cracking zone to ensure that the crushing zones of two adjacent blast holes are communicated; the charge length of each bore is 1/3-1/2 of the bore depth. The loading is a key parameter related to the pressure relief effect of blasting, and unreasonable loading not only can not achieve the pressure relief effect, but also can damage a roadway and even induce rock burst, so that reasonable loading is very important. The layer water injection is to inject water to the coal body through high pressure so as to change the physical properties of the coal body and generate cracks around the coal rock body, and the purposes of reducing the compressive strength of the coal body, destroying the original structure to release the accumulated energy and reducing the stress are achieved, and the unidirectional compressive strength of the coal measure stratum rock stratum is reduced along with the increase of the water content.

Optionally, the blasting mode adopts millisecond detonator group blasting, and the same group of sector holes are detonated simultaneously during blasting, so that the blasting effect is ensured.

In the embodiment, the microseismic method can monitor the mine earthquake caused by the mining activity of the whole mine area in a real-time long-distance and large-range manner, and can accurately calculate the position and the energy of the earthquake source.

The drilling cutting method is also called coal powder drilling method, and is a method for identifying impact danger by drilling small-diameter (41-50mm) holes in a coal seam according to the discharged coal powder quantity, the change rule thereof and related dynamic effect.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.