WO2023197573A1

WO2023197573A1 - Impact-prevention pressure-relief tunneling method for rock burst coal seam roadway

Info

Publication number: WO2023197573A1
Application number: PCT/CN2022/128958
Authority: WO
Inventors: 潘俊锋; 马文涛; 张晨阳; 高家明; 陆闯
Original assignee: 中煤科工开采研究院有限公司
Priority date: 2022-04-15
Filing date: 2022-11-01
Publication date: 2023-10-19
Also published as: AU2022453302A1; CN114856564A

Abstract

The present invention provides an impact-prevention pressure-relief tunneling method for a rock burst coal seam roadway, comprising: determining, in an area to be tunneled of a coal seam roadway, a fracturing target horizon satisfying a preset condition, and determining the number of directional drilling holes according to the number of layers of the fracturing target horizon; arranging a drill site in the coal seam roadway, constructing a directional drilling hole from the drill site to the fracturing target horizon, and fracturing the constructed directional drilling hole; continuing tunneling the coal seam roadway, if the length of a fracturing coverage area of an overlying top plate remains a preset length, arranging the drill site again, constructing a directional drilling hole from the drill site arranged again to the fracturing target horizon, and fracturing the constructed directional drilling hole.

Description

Anti-collision and pressure relief excavation method for rock-burdened coal seam tunnels

Cross-references to related applications

This application is filed based on a Chinese patent application with application number 202210397287.0 and a filing date of April 15, 2022, and claims the priority of the Chinese patent application. The entire content of the Chinese patent application is hereby incorporated into this application as a reference.

Technical field

The present disclosure relates to the technical field of safe mining of coal mines, in particular to an anti-collision and pressure-relief excavation method for rock-burdened coal seam tunnels.

Background technique

As the coal mine enters deep mining, the original rock stress is at a high level, and there are many folds, faults and other structures in the mine field. The original rock stress is superimposed on the structural stress to form a high concentrated stress foundation. During the tunnel excavation process, the support pressure is superimposed again to form a super-high concentration stress foundation. High stress concentration, thereby inducing shock ground pressure.

Local pressure relief measures such as coal seam blasting and large-diameter drilling are usually used to relieve pressure in excavation tunnels. On the one hand, large machinery, construction tools and supporting materials are concentrated in the excavation working face area. The pressure relief space is limited and conventional pressure relief measures lag behind. This results in a pressure relief blind zone at the excavation working face and a certain distance behind it; on the other hand, conventional local pressure relief measures have a limited range of pressure relief, and multiple rounds of pressure relief are often required during tunnel excavation, resulting in low pressure relief efficiency.

Contents of the invention

In view of the above problems, the present disclosure is proposed to provide an anti-collision and pressure relief excavation method for coal seam tunnels that overcomes the above problems or at least partially solves the above problems, and can regionally reduce the original rock stress and structural stress in the area where the tunnel is to be excavation. level, so that the area to be excavated in the tunnel is in a pressure relief protection zone, which effectively reduces the possibility of rock burst during tunnel excavation in coal seams.

According to one aspect of the embodiment of the present disclosure, a method for anti-collision and pressure relief excavation of coal seam tunnels under percussion is provided, including:

Determine the fracturing target layer that meets the preset conditions in the area to be excavated in the coal seam tunnel, and determine the number of directional drilling holes based on the number of layers of the fracturing target layer;

Set up a drilling field in the coal seam tunnel, start from the drilling field to construct the directional drilling to the fracturing target layer, and perform fracturing on the completed directional drilling;

Continue to dig into the coal seam tunnel. If the length of the fracturing coverage of the overlying roof remains the preset length, set up a drilling site again, and start directional drilling toward the fracturing target layer from the newly set up drilling site, and perform directional drilling on the completed directional drilling. The hole is fracturing.

Optionally, determine the fracturing target layer that meets the preset conditions in the area to be excavated in the coal seam tunnel, including:

Based on the borehole histogram, the rock layer with a thickness greater than the specified thickness within the preset height range is determined in the area to be excavated in the coal seam tunnel as the fracturing target layer.

Optionally, the rock layer with a specified thickness is a thick hard sandstone layer with a specified thickness.

Optionally, according to the borehole histogram, a rock layer with a height above the coal seam within a range of 40 m and a thickness greater than 8 m is determined as the fracturing target layer in the area to be dug in the coal seam tunnel.

Optionally, there are multiple fracturing target layers.

Optionally, a drilling field is set up in the coal seam tunnel, and the directional drilling is performed from the drilling field toward the fracturing target layer, including:

According to the height of the fracturing target layer at the highest position, a drilling site is set in the coal seam tunnel at a preset distance from the tunnel to be excavated;

Construct the directional drilling from the drilling site to the fracturing target layer, so that the tunnel to be excavated is in the horizontal projection area of the horizontal section of the directional drilling;

Among them, one layer of fracturing target layer corresponds to the construction of a directional drilling hole.

Optionally, the length of the horizontal section of the directional drilling is 600 to 1000m.

Optionally, if the directional drilling includes at least two, a drilling field is set up in the coal seam tunnel, the directional drilling is constructed from the drilling field to the fracturing target layer, and the completed directional drilling is Holes for fracturing, including:

Set up a drilling site in the coal seam tunnel, set the target fracturing layer for directional drilling and the sequence for fracturing;

Start constructing a first directional borehole from the drilling site to the first fracturing target layer, and perform fracturing on the completed first directional borehole;

Start constructing the second directional drilling to the second fracturing target layer from the drilling site, and perform fracturing on the completed second directional drilling until all the directional drilling and fracturing target layers are completed and fracturing. Split is completed.

Optionally, perform fracturing on completed directional boreholes, including:

High-pressure water is injected into the horizontal sections of the completed directional boreholes, and hydraulic fracturing is performed on the horizontal sections of the directional boreholes.

Optionally, high-pressure water is injected into the horizontal sections of the completed directional boreholes, and hydraulic fracturing is performed on the horizontal sections of the directional boreholes, including:

Send the packer into the direction of the hole bottom of the directional borehole, and inject high-pressure water into the hole section blocked by the packer to perform hydraulic fracturing;

Retreat the packer to the next position at a specified distance, and inject high-pressure water into the hole section currently blocked by the packer to perform hydraulic fracturing until the next position of the packer retreats beyond the specified distance. Horizontal section of directional drilling.

Optionally, the length of the hole section for each pressurization is 15m.

Optionally, when the length of the overlying roof fracturing coverage remains 100m, the drilling site is set up again.

The embodiment of the present disclosure first determines the fracturing target layer that meets the preset conditions in the area to be excavated in the coal seam tunnel, and determines the number of directional drilling holes based on the number of fracturing target layer layers, and then sets up a drilling site in the coal seam tunnel. , construct directional drilling from the drilling site to the fracturing target layer, perform fracturing on the completed directional drilling, and then continue to excavate the coal seam tunnel. If the length of the overlying roof fracturing coverage area remains the preset length, set it again At the drilling site, directional drilling is started from the newly set up drilling site to the target fracturing layer, and fracturing is performed on the completed directional drilling. Therefore, the embodiment of the present disclosure can use directional drilling to carry out large-scale fracturing and pressure relief on the thick hard roof overlying the roadway in the area to be excavation. Moreover, the drilling site is set up, the directional drilling is constructed, and the directional drilling is carried out through a cycle. By fracturing the holes, the thick hard roof plate overlying the tunnel can be continuously pre-cracked, and the original rock stress and structural stress level of the tunnel to be tunneled can be reduced regionally and in advance, so that the tunnel to be tunneled is in a pressure relief protection zone, effectively reducing the The possibility of rockburst during coal seam tunnel excavation.

The above description is only an overview of the technical solutions of the present disclosure. In order to have a clearer understanding of the technical means of the present disclosure, they can be implemented according to the content of the description, and in order to make the above and other objects, features and advantages of the present disclosure more obvious and understandable. , the specific implementation modes of the present disclosure are specifically listed below.

The above and other objects, advantages and features of the present disclosure will be more apparent to those skilled in the art from the following detailed description of specific embodiments of the present disclosure in conjunction with the accompanying drawings.

Description of the drawings

The drawings described here are used to provide a further understanding of the present disclosure and constitute a part of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation of the present disclosure. In the attached picture:

Figure 1 shows a schematic flowchart of a method for anti-collision and pressure relief excavation of coal seam tunnels under percussion rock formation according to an embodiment of the present disclosure;

Figure 2 shows a schematic diagram of directional drilling and directional drilling fracturing of a thick hard rock layer overlying a tunnel to be excavated according to an embodiment of the present disclosure;

Figure 3 shows a schematic cross-sectional view of directional drilling and directional drilling and fracturing of the thick hard rock layer overlying the tunnel to be excavated according to an embodiment of the present disclosure;

In the picture: 1: Tunnel that has been dug; 2: Drilling site; 3: Directional drilling; 4: Fracturing point of hole section; 5: Tunnel to be dug; 6: Fracturing cracks.

Detailed ways

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a thorough understanding of the disclosure, and to fully convey the scope of the disclosure to those skilled in the art.

In order to solve the above technical problems, embodiments of the present disclosure provide an anti-collision and pressure-relieving excavation method for percussion coal seam tunnels. Figure 1 shows an anti-collision and pressure-relief excavation method for percussion coal seam tunnels according to an embodiment of the present disclosure. Process diagram. Referring to Figure 1, the anti-collision and pressure relief excavation method for rock-burdened coal seam tunnels includes the following steps S102 to S106.

Step S102: Determine the fracturing target layer that meets the preset conditions in the area to be excavated in the coal seam tunnel, and determine the number of directional drilling holes based on the number of layers of the fracturing target layer.

Step S104: Set up a drilling field in the coal seam tunnel, construct directional drilling from the drilling field to the fracturing target layer, and perform fracturing on the completed directional drilling.

Step S106, continue to excavate the coal seam tunnel. If the length of the overlying roof fracturing coverage remains the preset length, set up the drilling site again, start directional drilling toward the fracturing target layer from the re-set drilling site, and complete the construction. Directional drilling for fracturing.

Embodiments of the present disclosure can use directional drilling to carry out large-scale fracturing and pressure relief on the thick hard roof covering the tunnel at one time in the area to be excavation. Moreover, the drilling site is set up, the directional drilling is constructed, and the directional drilling is carried out through a cycle. Cracks can be used to continuously pre-crack the thick hard roof covering the tunnel, regionally advance the stress and structural stress levels of the original rock in the area to be excavated, reduce the dynamic and static load sources that induce impact initiation, and increase the threshold for the occurrence of rock bursts, so that The area of the tunnel to be excavated is in a pressure relief protection zone. After the fracturing of the thick hard roof on the coal seam tunnel, the excavation of the tunnel within the fracturing coverage area and the use of the tunnel are in a low-stress zone. The tunnel and the workers in the tunnel can be effectively protected, reducing the impact The possibility of rockburst during tunnel excavation in underground coal seams.

In an embodiment of the present disclosure, since the borehole histogram describes the layering, thickness, lithology, structural structure and contact relationship of the rock formation through which the borehole passes, groundwater sampling and testing, borehole structure and drilling, etc., It can be used as an important basis for analyzing the geological conditions of coal mines. Therefore, the embodiment of the present disclosure can determine the fracturing target layer above the coal seam based on the borehole histogram.

Specifically, in the process of performing step S102 to determine the fracturing target layer that meets the preset conditions in the area to be excavated of the coal seam tunnel, it is possible to determine in the area to be excavated of the coal seam tunnel based on the borehole histogram that the thickness is greater than the specified height within the preset height range. The thickness of the rock layer is used as the target layer for fracturing. For example, the rock layer with a height above the coal seam within a range of 40 m and a thickness greater than 8 m can be determined as the fracturing target layer in the area to be excavated in the coal seam tunnel based on the borehole histogram.

In the embodiment of the present disclosure, the rock layer with a height within the range of 40m and a thickness greater than 8m may be a thick hard sandstone layer. Referring to Figures 2 and 3, in a coal mine, the thickness of the fine-grained sandstone layer above the coal seam is 10.2m, and the thickness of the siltstone layer is 11m. Both thicknesses are greater than 8m, and the height from the coal seam is within 40m. , thus, there are two target fracturing layers in this embodiment, namely the fine-grained sandstone layer and the siltstone layer.

Normally, one layer of fracturing target layer can correspond to one directional borehole. If the fracturing target layer contains two layers, then two directional boreholes will be constructed. If the fracturing target layer contains three layers, then three layers will be constructed. One directional borehole will be constructed for each fracturing target layer.

Referring to step S104, in an embodiment of the present disclosure, a drilling field 2 is set up in the coal seam tunnel (such as the tunnel 1 that has been excavated). The specific process of constructing directional drilling from the drilling field 2 to the fracturing target layer is as follows:

First, according to the height of the fracturing target layer at the highest position, a drilling site 2 is set up in the coal seam tunnel at a preset distance from the tunnel to be excavated 5 .

In this embodiment, the height according to the fracturing target layer at the highest position refers to the uppermost fracturing target layer. For example, if there is only one fracturing target layer, then according to the height of the fracturing target layer, select the location of drill field 2 at a preset distance from the tunnel to be dug 5 in the coal seam tunnel, and set drill field 2. If the fracturing target layer contains at least two, then the uppermost fracturing target layer is the fracturing target layer at the highest position. After measuring the height of the fracturing target layer at the highest position, according to the highest position Select the location of drilling field 2 at the fracturing target layer height and set drilling field 2.

In this embodiment, according to the height of the fracturing target layer at the highest position, when selecting a position at a preset distance from the tunnel 5 to be excavated in the coal seam tunnel as the location of the drilling site 2, the selection criterion is to ensure that the tunnel area to be excavated is in The horizontal projection area of the horizontal section of the directional borehole 3 is such that the tunnel area to be excavated is within the coverage of roof fracturing. In order to meet the selection criteria, the set drilling field 2 locations will be different for different fracturing target layer heights. For example, for the height of the fine-grained sandstone layer shown in Figure 2, the preset distance can be set to 100m. Of course, it can also be other distances. This embodiment can effectively avoid the directional drilling 3 located above the tunnel area to be excavated. Inclined section to prevent fracturing blind spots.

Then, a directional borehole 3 is constructed from the drilling field 2 to the fracturing target layer, so that the tunnel 5 to be dug is in the horizontal projection area of the horizontal section of the directional borehole 3.

During the construction of the directional borehole 3 in the embodiment of the present disclosure, the horizontal section of the directional borehole 3 is located directly above the tunnel area to be excavated. For example, the horizontal section of the directional borehole 3 can be constructed during one construction of the directional borehole 3. The length is 600-1000m. Therefore, in the subsequent area to be excavation, directional long holes can be used to fracturing and relieve pressure on a large scale overlying the thick hard roof of the tunnel at one time.

In this embodiment, if the fracturing target layers contain at least two, and the corresponding directional boreholes also contain at least two (directional boreholes 3 and 3' in Figure 2), then starting from the same drilling site 2 Each directional borehole 3 is constructed to each fracturing target layer, so that one directional borehole 3 is constructed for each fracturing target layer.

Combined with Figure 2 and Figure 3, the target fracturing layers are a fine-grained sandstone layer with a thickness of 10.2m and a siltstone layer with a thickness of 11m above the coal seam respectively. In the embodiment of the present disclosure, fracturing can start from the drilling site 2 and penetrate into the fine-grained sandstone layer. A directional drilling 3 will be constructed at a position 22m above the coal seam, and a directional drilling 3' will be constructed from the drilling site 2 to a position 40m above the coal seam in the siltstone layer.

In an embodiment of the present disclosure, if there are at least two directional boreholes, in step S104, the directional boreholes are constructed separately from the drilling site 2 to the fracturing target layer, and the completed directional boreholes are fractured. , you can also first set the sequence of directional drilling and fracturing at the target fracturing layer. Then, start from drilling field 2 to construct the first directional borehole (such as directional borehole 3’) toward the first fracturing target layer, and perform fracturing on the completed first directional borehole. Then, start from drilling site 2 to construct a second directional borehole (such as directional borehole 3) to the second fracturing target layer, and perform fracturing on the completed second directional borehole until all fracturing target layers are The construction has completed directional drilling and fracturing.

Therefore, in the embodiment of the present disclosure, by setting the construction sequence and fracturing sequence of directional drilling at different fracturing target layers, each fracturing target layer can be fractured sequentially according to the setting order, avoiding the need to fracturing each directional drilling process. Drilling construction creates interference.

In the embodiment of the present disclosure, the method of fracturing the completed directional boreholes can be hydraulic fracturing, that is, injecting high-pressure water into the horizontal sections of the completed directional boreholes in sections, thereby fracturing the horizontal sections of the directional boreholes. Staged hydraulic fracturing is carried out section by section. In an optional embodiment, high-pressure water is injected into the horizontal sections of the completed directional boreholes, and the method of performing segmented hydraulic fracturing on the horizontal sections of the directional boreholes may be:

First, the packer is sent into the direction of the hole bottom of the directional borehole, and high-pressure water is injected into the hole section sealed by the packer to perform hydraulic fracturing;

Then, retreat the packer to the next position at a specified distance, and inject high-pressure water into the hole section currently blocked by the packer to perform hydraulic fracturing until the next position of the packer retreat exceeds the horizontal section of the directional drilling. .

The specified distance for this embodiment may be 15m, that is, the length of the hole section for each pressure is approximately 15m. For the case where multiple directional boreholes are constructed from one drilling site 2 to multiple fracturing target layers, the drilling and fracturing work of each directional borehole can be completed in sequence.

In this embodiment, high-pressure water applies high pressure to the inside of the directional borehole, starting from the fracturing point 4 of a hole section and extending around the directional borehole to form a fracturing crack 6, so as to achieve fracturing of the rocks around the directional borehole.

Referring to the above step S106, in one embodiment of the present disclosure, if the length of the overlying roof fracturing coverage area remains the preset length, the drilling site is set up again, and the construction direction is started from the re-set drilling site toward the fracturing target layer. Drilling holes and fracturing the completed directional drilling holes.

After the directional drilling is completed and the hydraulic fracturing of the thick hard roof overlying the tunnel to be excavation is completed through directional drilling, the percussion coal seam tunnel excavation is carried out. When a certain distance remains in the length of the overlying roof fracturing coverage (such as When the remaining 100m), the drilling field is set up again and directional drilling is performed at the target fracturing layer. Through the directional drilling again, the area covered by the thick hard roof plate in the tunnel to be excavation is pre-cracked and the area where hydraulic fracturing has not been carried out is carried out, and so on. , the process of setting up a drilling site, constructing directional drilling, and fracturing the directional drilling is executed cyclically until the tunnel excavation is completed, thereby ensuring that the tunnel excavation process is within the fracturing coverage of the overlying roof.

Therefore, the embodiment of the present disclosure can carry out excavation in the fracturing coverage area after the thick hard roof plate on the tunnel to be excavation is pre-cracked, so that the working face is in a low-stress zone during excavation and use, avoiding an increase in the risk of impact caused by stress concentration. high.

The disclosed embodiment performs regional pre-cracking on the thick hard roof plate covering the tunnel to be excavated in the percussion coal seam to realize the transformation of the thick hard roof into a fragmented roof, which greatly reduces the stress concentration during tunnel excavation and can expand the fracturing coverage area. The low-stress area enables smooth tunnel excavation, so that the working face is protected during excavation and use, thereby effectively reducing the risk of impact.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present disclosure, but not to limit it; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: Within the spirit and principles of the present disclosure, it is still possible to modify the technical solutions recorded in the foregoing embodiments, or to make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not deviate from the corresponding technical solutions. scope of the present disclosure.

Claims

An anti-collision and pressure relief excavation method for rock-burdened coal seam tunnels, including:

Determine the fracturing target layer that meets the preset conditions in the area to be excavated in the coal seam tunnel, and determine the number of directional drilling holes based on the number of layers of the fracturing target layer;

Set up a drilling field in the coal seam tunnel, start from the drilling field to construct the directional drilling to the fracturing target layer, and perform fracturing on the completed directional drilling;

Continue to dig into the coal seam tunnel. If the length of the fracturing coverage of the overlying roof remains the preset length, set up a drilling site again, and start directional drilling toward the fracturing target layer from the newly set up drilling site, and perform directional drilling on the completed directional drilling. The hole is fracturing.
The method according to claim 1, wherein determining the fracturing target layer that meets preset conditions in the area to be tunneled in the coal seam tunnel includes:

Based on the borehole histogram, the rock layer with a thickness greater than the specified thickness within the preset height range is determined in the area to be excavated in the coal seam tunnel as the fracturing target layer.
The method of claim 2, wherein the rock formation of a specified thickness is a thick hard sandstone layer of a specified thickness.
The method according to claim 2 or 3, wherein a rock layer with a height above the coal seam within a range of 40m and a thickness greater than 8m is determined in the area to be dug in the coal seam tunnel according to the borehole histogram as the pressure layer. Split the target layer.
The method according to any one of claims 2 to 4, wherein the fracturing target layers are multiple.
The method according to any one of claims 1 to 5, wherein a drilling field is set up in the coal seam tunnel, and the directional drilling is constructed from the drilling field toward the fracturing target layer, including:

According to the height of the fracturing target layer at the highest position, a drilling site is set in the coal seam tunnel at a preset distance from the tunnel to be excavated;

Construct the directional drilling from the drilling site to the fracturing target layer, so that the tunnel to be excavated is in the horizontal projection area of the horizontal section of the directional drilling;

Among them, one layer of fracturing target layer corresponds to the construction of a directional drilling hole.
The method according to claim 6, wherein the length of the horizontal section of the directional borehole is 600 to 1000 m.
The method according to any one of claims 1 to 7, wherein if the directional drilling includes at least two, a drilling field is set up in the coal seam tunnel, and construction starts from the drilling field toward the fracturing target layer. The directional drilling involves fracturing the completed directional drilling, including:

Set up a drilling site in the coal seam tunnel, set the target fracturing layer for directional drilling and the sequence for fracturing;

Start constructing a first directional borehole from the drilling site to the first fracturing target layer, and perform fracturing on the completed first directional borehole;

Start constructing the second directional drilling to the second fracturing target layer from the drilling site, and perform fracturing on the completed second directional drilling until all the directional drilling and fracturing target layers are completed and fracturing. Split is completed.
The method according to any one of claims 1 to 8, wherein fracturing the completed directional boreholes includes:

High-pressure water is injected into the horizontal sections of the completed directional boreholes, and hydraulic fracturing is performed on the horizontal sections of the directional boreholes.
The method according to claim 9, wherein high-pressure water is injected into the horizontal sections of the completed directional boreholes in sections, and segmented hydraulic fracturing is performed on the horizontal sections of the directional boreholes, including:

Send the packer into the direction of the hole bottom of the directional borehole, and inject high-pressure water into the hole section blocked by the packer to perform hydraulic fracturing;

Retreat the packer to the next position at a specified distance, and inject high-pressure water into the hole section currently blocked by the packer to perform hydraulic fracturing until the next position of the packer retreats beyond the specified distance. Horizontal section of directional drilling.
The method according to claim 10, wherein the length of the hole section for each pressurization is 15m.
A method according to any one of claims 1 to 11, wherein the drilling site is set up again when 100m of the length of the overlying roof fracturing coverage remains.