CN109555502B - Industrial test method for presplitting permeability increase of high-gas coal roadway - Google Patents
Industrial test method for presplitting permeability increase of high-gas coal roadway Download PDFInfo
- Publication number
- CN109555502B CN109555502B CN201811347511.5A CN201811347511A CN109555502B CN 109555502 B CN109555502 B CN 109555502B CN 201811347511 A CN201811347511 A CN 201811347511A CN 109555502 B CN109555502 B CN 109555502B
- Authority
- CN
- China
- Prior art keywords
- gas
- roadway
- fracturing
- monitoring
- holes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 239000003245 coal Substances 0.000 title claims abstract description 78
- 230000035699 permeability Effects 0.000 title claims abstract description 27
- 238000010998 test method Methods 0.000 title claims abstract description 15
- 230000005641 tunneling Effects 0.000 claims abstract description 88
- 238000012544 monitoring process Methods 0.000 claims abstract description 73
- 238000006073 displacement reaction Methods 0.000 claims abstract description 56
- 239000011435 rock Substances 0.000 claims abstract description 49
- 238000000605 extraction Methods 0.000 claims abstract description 38
- 230000000694 effects Effects 0.000 claims abstract description 34
- 238000005553 drilling Methods 0.000 claims abstract description 31
- 238000000926 separation method Methods 0.000 claims abstract description 19
- 238000013461 design Methods 0.000 claims abstract description 14
- 238000005086 pumping Methods 0.000 claims abstract description 10
- 238000012806 monitoring device Methods 0.000 claims abstract description 6
- 230000008859 change Effects 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 19
- 238000004458 analytical method Methods 0.000 claims description 17
- 238000012360 testing method Methods 0.000 claims description 13
- 230000006872 improvement Effects 0.000 claims description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims 1
- 238000005336 cracking Methods 0.000 abstract description 9
- 239000007789 gas Substances 0.000 description 129
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 44
- 239000002390 adhesive tape Substances 0.000 description 28
- 238000005516 engineering process Methods 0.000 description 24
- 229910002092 carbon dioxide Inorganic materials 0.000 description 23
- 230000002829 reductive effect Effects 0.000 description 19
- 230000008093 supporting effect Effects 0.000 description 19
- 238000009826 distribution Methods 0.000 description 13
- 238000005065 mining Methods 0.000 description 12
- 238000010276 construction Methods 0.000 description 11
- 230000032798 delamination Effects 0.000 description 11
- 238000004873 anchoring Methods 0.000 description 10
- 238000005422 blasting Methods 0.000 description 10
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 6
- 238000009412 basement excavation Methods 0.000 description 5
- 239000001569 carbon dioxide Substances 0.000 description 5
- 239000003345 natural gas Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000002184 metal Substances 0.000 description 3
- 230000000246 remedial effect Effects 0.000 description 3
- 238000007789 sealing Methods 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000009659 non-destructive testing Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 230000036962 time dependent Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000010835 comparative analysis Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000004047 hole gas Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/006—Production of coal-bed methane
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/30—Specific pattern of wells, e.g. optimising the spacing of wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Geology (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Environmental & Geological Engineering (AREA)
- Architecture (AREA)
- Structural Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Geophysics (AREA)
- Civil Engineering (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
The application discloses an industrial test method for pre-splitting permeability increase of a high-gas coal roadway, which comprises the following steps of: arranging monitoring devices for realizing roadway surface displacement monitoring, roadway roof separation monitoring, roadway surrounding rock deep multi-point displacement monitoring and anchor rod and/or anchor cable stress monitoring at set positions; arranging fracturing holes at a tunneling surface, arranging gas drilling sites at two sides of the tunneling surface, arranging pre-pumping holes at the drilling sites, performing CO2 pre-cracking on the fracturing holes, and pumping gas from the pre-pumping holes; performing advanced grouting on a small guide pipe on a driving working face; and analyzing the gas extraction effect and the permanent support effect of the driving face before and after fracturing, and judging the rationality of related design parameters by combining the monitoring data acquired by the monitoring device.
Description
Technical Field
The disclosure generally relates to the technical field of coal roadway mining, in particular to an industrial test method for pre-splitting permeability improvement of a high-gas coal roadway.
Background
At present, many coal mines in China are high gas mines, and with the continuous increase of the total quantity of coal requirements, mining is continuously promoted to the deep part, and the occurrence content of gas in the deep coal seam is greatly increased. For a deep low-permeability high-gas coal seam, conventional gas drainage methods such as pre-drainage, coal seam drainage and the like are difficult to effectively enable a large amount of gas in the coal seam to be separated out, so that the gas pressure in the coal seam is extremely high. The main problems that exist are: the effective influence range of the drill hole is small, the construction workload is large, the drainage efficiency is low, and effective technical measures such as pressure relief and permeability increase, the effective influence range of the drill hole expansion, the drill hole sealing effect improvement and the like need to be taken so as to achieve the purpose of improving the gas drainage efficiency. During the tunneling of the coal seam tunnel, the gas overrun condition occurs frequently, the tunneling speed of the tunnel is reduced, the normal replacing work is influenced, and the safe and normal production of the tunneling surface is seriously influenced. How to effectively solve the influence of high gas in coal seam tunneling is not slow enough.
Aiming at the occurrence characteristics of high gas in a coal seam, some effective attempts are made on the existing coal seam tunneling surface, namely CO is adopted2And (3) a pre-splitting permeability-increasing technology. Utilization of CO in high gas zones of coal seam tunnels2The presplitting technology enlarges the air permeability of the coal seam, and greatly increases the gas extraction concentration. But the pre-splitting also ensures that the distribution range of the coal body fractures is larger than that of the prior art, and the crushing degree of the coal seam roadway top plate is more serious. In terms of gas extraction effect, when the pre-splitting range is large, the extraction effect is better. However, if the pre-cracking is excessive, the roof fall accident of the heading face is easily caused. In the prior art, no good method can ensure that the related design in actual construction can effectively control the presplitting range.
Disclosure of Invention
In view of the above-mentioned defects or shortcomings in the prior art, it is desirable to provide an industrial testing method for pre-splitting permeability increase of a high gas coal roadway.
In a first aspect, an embodiment of the present application provides an industrial test method for pre-splitting permeability increase of a high gas coal roadway, including the following steps:
arranging monitoring devices for realizing roadway surface displacement monitoring, roadway roof separation monitoring, roadway surrounding rock deep multi-point displacement monitoring and anchor rod and/or anchor cable stress monitoring at set positions;
arranging fracturing holes at a tunneling surface, arranging gas drilling sites at two sides of the tunneling surface, arranging pre-pumping holes at the drilling sites, performing CO2 pre-cracking on the fracturing holes, and pumping gas from the pre-pumping holes;
performing advanced grouting on a small guide pipe on a driving working face;
and analyzing the gas extraction effect and the permanent support effect of the driving face before and after fracturing, and judging the rationality of related design parameters by combining the monitoring data acquired by the monitoring device.
The roadway surface displacement monitoring content comprises: the subsidence of the top and bottom plates, the bottom bulging amount and the moving approach amount of the two sides can comprehensively understand the distribution range of the coal body fractures in the construction design scheme, thereby realizing the effective control of the pre-splitting range in the subsequent construction.
The inclination angle of the drill hole of the pre-drainage hole is substantially consistent with the trend of the coal bed, and the inclination angle is adjusted according to the actual situation, so that the air permeability of the fractured coal bed can be further increased, and the gas extraction is further increased.
The drilling production adopts stepping arrangement, the interval between the same sides is 110-130m, and the interval between the opposite sides is 55-65 m.
And a plurality of the pre-drawing holes are arranged at the same drilling site, the distance between the drilling holes in the same row is 0.55-0.65m, and the distance between the drilling holes in two adjacent rows in the same row is 0.15-0.25 m.
The design depth of the fracturing holes is approximately the same as the interval distance of the different sides of the drilling field, and the fracturing holes are arranged along the natural inclination angle of the coal body in the middle of the driving face, so that the fracture expansion of the coal bed can be improved, and the crushing degree of the top of the coal bed roadway can be reduced.
The fracturing holes are directional fracturing holes, namely wedge-shaped grooves are arranged on two sides of the fracturing holes in the horizontal direction, so that directional fracturing can be realized, the range of cracks on the top is reduced while the transverse crack extension area of a coal seam is enlarged, and roof fall accidents of a tunneling surface can be greatly reduced.
After the CO2 pre-splitting is completed, arranging a gas release drill hole at the tunneling surface, and extracting gas from the gas release drill hole, so that the gas extraction effect can be further improved while the safety is ensured.
The content of gas extraction effect analysis before and after fracturing comprises the following steps: the change rule of the gas flow of the drilled hole before and after fracturing, the permeability coefficient of the coal bed, the gas extraction concentration, the gas emission uniformity and the gas emission unbalance coefficient. By analyzing the above contents, the comprehensive analysis of the gas extraction effect can be obtained, and auxiliary support is provided for the analysis of the fracture distribution range.
When the reasonability of the related design parameters is judged, the analysis of the change rule of the tunneling speed of the roadway before and after fracturing and the change rule of the hectometre gas early warning times is also included, so that the whole construction efficiency of the construction design scheme can be known.
According to the industrial test method for pre-splitting permeability increase of the high-gas coal roadway, in order to solve potential hazards of high gas, gas drilling fields are arranged on two sides of the tunneling face, and the technology of pre-pumping and CO2 high-pressure gas cracking is combined, so that the gas permeability of a coal seam is increased, the gas extraction of the tunneling face is increased, and the danger of gas outburst is eliminated. The gas extraction effect is better, and meanwhile roof collapse accidents are avoided.
The crack rate of coal bodies in a certain range of the tunneling surface is increased due to the cracking of the tunneling surface CO2, the stability of surrounding rocks is reduced, the possibility of roof fall is increased, and the normal propulsion of the tunneling surface is influenced. Therefore, a roof fall control mechanism of a high-gas large-section soft coal seam tunneling face must be researched, and a specific prevention measure is provided for roof fall of a rubber belt downhill tunneling face. The method comprises the optimization of temporary support, and under the condition, the traditional metal beam temporary support is changed, because the metal beam belongs to passive support, the bearing capacity is limited, and the stability of the tunneling surface cannot be effectively ensured. The method adopts a small-conduit advanced grouting technology to strengthen the temporary supporting effect of the excavation face; on the basis of temporary support, permanent support design is carried out on the driving surface of the adhesive tape going downhill, and the permanent support of the adhesive tape going downhill is mainly realized by utilizing an anchor rod, an anchor cable and a combined member system. And (3) carrying out an industrial test method on the on-site tunneling surface, and observing the coal body fracture distribution, the gas extraction effect and the roof fall control effect under the CO2 pre-splitting condition. By monitoring of a field test, the fracture distribution range of the top coal, the penetration degree of the fractures, the top integrity of the driving face and the change condition of the gas extraction content before and after fracturing can be obtained, the presplitting range can be effectively controlled by related design, and the requirement of the gas extraction content is met.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:
FIG. 1 shows a schematic view of a monitoring section of roadway surface displacement in an embodiment of the application;
FIG. 2 shows a mounting diagram of a roof delamination indicator in an embodiment of the application;
FIG. 3 shows a deep displacement measuring point layout diagram of a heading face in the embodiment of the application;
FIG. 4 shows a gas phase fracturing construction technique parameter chart in the embodiment of the application;
FIG. 5 is a sectional view of a pre-extraction drill hole of a 23-mining-area adhesive tape down-hill drill site in the embodiment of the application;
FIG. 6 shows a parameter diagram of the construction of the adhesive tape downward hill and upward head drilling in the 23 mining areas in the embodiment of the application;
FIG. 7 shows a front view of a pre-extraction borehole in a 23-panel adhesive tape down-hill 1 drill site in an embodiment of the present application;
FIG. 8 shows a top view of a pre-pump induced fracture remedial drilling arrangement in an embodiment of the present application;
FIG. 9 shows a front view of a pre-pump induced fracture remedial drilling arrangement in an embodiment of the present application;
FIG. 10 shows a side view of a pre-pump induced fracture remedial drilling arrangement in an embodiment of the present application;
FIG. 11 is a table showing a summary of natural gas flows in the embodiment of the present application;
FIG. 12 shows a natural gas flow chart of a pre-split fore-and-aft borehole in an embodiment of the present application;
FIG. 13 shows the gas extraction concentration variation trend before and after carbon dioxide blasting in the embodiment of the application;
FIG. 14 is a table showing the comparison of the effects before and after carbon dioxide fracturing in the examples of the present application;
FIG. 15 is a graph showing a change of the concentration of the return air flow gas of the driving face under the adhesive tape in the embodiment of the application;
FIG. 16 is a graph showing the variation of the gas concentration of the return air flow of the driving face under the adhesive tape in the embodiment of the application;
FIG. 17 is a diagram showing the variation of the coefficient of imbalance of gas emission of the driving face under the condition that the adhesive tape is lowered onto the mountain in the embodiment of the application;
FIG. 18 shows a monthly tunneling condition statistical table of the tape mountain descending tunneling surface in the embodiment of the present application;
FIG. 19 is a graph showing the average daily footage of the tape in the driving of the lower mountain and the change of the driving speed of the tape in the embodiment of the present application;
FIG. 20 is a graph showing a comparison analysis of the number of hectometer gas warnings in the embodiment of the present application;
FIG. 21 shows a displacement cloud before grouting in an embodiment of the present application;
FIG. 22 is a graph showing the displacement history of monitoring points before grouting in the embodiment of the present application;
FIG. 23 shows a displacement cloud after grouting in an embodiment of the present application;
FIG. 24 is a graph showing the displacement history of monitoring points before grouting in the embodiment of the present application;
FIG. 25 shows the maximum displacement of surrounding rock of a belt downhill monitoring section of a 23 mining area in the embodiment of the application;
FIG. 26 is a graph showing the displacement of the monitored surrounding rock section 1 under the adhesive tape in the embodiment of the application as a function of time;
FIG. 27 shows a summary table of maximum values of the subsidence of the top plate of the heading face during observation in the embodiment of the present application;
FIG. 28 shows a graph of the relation between the top plate sinking and the observation time of the driving face under the adhesive tape in the embodiment of the application;
FIG. 29 shows a time-dependent variation curve of the roof separation amount of the heading face in the embodiment of the application;
FIG. 30 shows the time-dependent stress of anchor cables on the heading face in the embodiment of the application;
FIG. 31 shows the distribution rule of the advance support pressure of the heading face in the embodiment of the application;
figure 32 shows the face leading support pressure distribution feature in an embodiment of the present application;
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the described embodiments are only a part, and not all, of the present invention. For convenience of description, only portions related to the invention are shown in the drawings.
It will be readily understood that the components of the embodiments of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations without departing from the scope of the present invention. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
1. Monitoring content and arrangement mode
1.1 monitoring content and purpose
(1) Roadway surface displacement monitoring
The roadway surface displacement monitoring is the most basic roadway mine pressure monitoring content and comprises a top bottom plate sinking amount, a bottom bulging amount, two side approaching amounts and the like. According to the monitoring result, a relation curve of the displacement and the time can be drawn, the deformation rule of the surrounding rock of the roadway is analyzed, and the stability of the surrounding rock and the supporting effect of the roadway are evaluated.
(2) Roadway roof separation monitoring
The displacement of the different degree of depth of roof is different, and the displacement of general shallow portion country rock is great, and the displacement of deep country rock is less, leads to shallow and deep stratum to appear the displacement difference. The roadway roof separation layer refers to the displacement difference between the surrounding rock at the shallow part and the surrounding rock at the deep part of the roadway. When the roof separation reaches a certain value, the roof is likely to be damaged and fall, and the roof separation is a precursor of instability of surrounding rocks of the roadway. The model of the roof separation instrument is DZY-8m, the measuring ranges of the inner measuring cylinder and the outer measuring cylinder are 0-150mm, wherein the blue area is 0-50mm, the yellow area is 50-100mm, and the red area is 100-150 mm. The roof separation size inside and outside the anchor zone of the anchor bolt supporting roadway is measured, and the method has important significance for evaluating the anchor bolt supporting effect and the roadway safety degree.
(3) Roadway surrounding rock deep multi-point displacement monitoring
The deformation of different depths of surrounding rock of the driving face is different, and the multipoint displacement meter is an instrument for monitoring the change of the deformation of the surrounding rock at the deep part along with the time in the whole service period of the driving and the mining influence of the roadway. Through measuring the displacement volume of the different degree of depth of tunnel country rock, can audio-visually master the deformation destruction characteristic of country rock, to evaluation roadway support effect and tunnel safety degree have the significance.
(4) Anchor rod (cable) stress monitoring
In the anchor rod (cable) support engineering, the stress of the anchor rod (cable) has great influence on the stability of the roadway, so that the stress of the anchor rod (cable) is monitored on the excavation surface supported according to the design scheme so as to master the bearing working condition of the anchor rod (cable), the deformation characteristic of surrounding rocks and the supporting condition of the roadway, and meanwhile, a basis is provided for modifying and adjusting the support design.
1.2 survey station arrangement and monitoring method
(1) Roadway surface displacement monitoring station arrangement and monitoring method
The roadway surface displacement is usually monitored by adopting a cross-shaped point arrangement method, and the arrangement of the surface displacement monitoring points on the heading surface is shown in fig. 1. And drilling holes in the vertical direction and the horizontal direction of the two sides in the middle of the top and bottom plates, and installing measuring base points such as timber piles, measuring nails and the like. Two monitoring sections are generally arranged at one measuring point, and the axial interval of the two monitoring sections along the roadway is 1.0 m. And during monitoring, values of AO, AB, CO and CD are taken, and the sinking amount of the top plate, the bottom bulging amount and the displacement of the upper are obtained through calculation. The measurement frequency is determined according to the deformation of the surrounding rock of the roadway, when the horizontal distance between a measuring point and the tunneling surface is within 50m, the measuring point is observed once a day, other measuring points are observed 1-2 times a week, and the monitoring time is 2 months. The distance between the roadway surface displacement monitoring measuring stations is 50m, and the horizontal distance between the first measuring point (the rightmost measuring point) and the tunneling surface is 30 m.
(2) Arrangement and monitoring method for tunneling face roof separation layer measuring station
Roof delamination monitoring was performed using a delamination indicator mounted in the roof, as shown in fig. 2. The roof separation indicator comprises a deep base point and a shallow base point, and the relative displacement between the roadway surface and the shallow base point and between the shallow base point and the deep base point are respectively tested. When the top plate is not delaminated, the displacement change rates of the shallow base points and the deep base points are gradually decreased and finally approach to 0, and if a jump occurs in the middle, it is possible to determine whether or not the top plate is delaminated and the delaminated portion is present.
Because the top plate of the driving face under the adhesive tape is a thick composite top plateAccording to the lithology characteristics of the top plate, a deep base point is fixed 8m above the top plate, and a shallow base point is fixed at the end position of the anchor rod. The basic working principle of the top plate delamination apparatus is that the total delamination amount of the top plate is measured by measuring the relative displacement change between a deep base point and the surface of the top plate
And measuring the amount of delamination of the top plate in the anchoring zone from the change in the relative displacement of the base point of the shallow portion and the surface of the top plate
The amount of delamination outside the anchoring zone of the top plate is
. Frequency of monitoring roof delamination: within the range of 0-10 m from the tunneling surface, 2 times/d; in the range of 11-20 m, 1 time/d; within the range of 21-50 m, 1 time/3 d; when the roadway is stable, the observation interval can be increased. And installing an off-level indicator every 50m, and carrying out card hanging management. The horizontal distance of the first measuring point (the rightmost measuring point) of the top plate from the layer monitoring to the cutting hole is 10 m.
(3) Arrangement and monitoring method of tunnel surrounding rock deep multi-point displacement monitoring survey station
The test adopts DWJ-2 type multipoint displacement meter developed by China mining university. According to the measurement requirement, 6 measuring points are arranged in each drilling hole, the depth of each measuring point is 6m, 5m, 4m, 3m, 2m and 1m, an in-hole fixer is installed on one measuring point, and the arrangement of the measuring points is shown in figure 3. After the multipoint displacement meter is installed, the initial reading of each measuring point is read out firstly, and the difference between the value read out each time and the initial reading is the displacement value of the measuring point. The monitoring frequency of the multipoint displacement is generally 2-3 times of measurement and reading in the first week after construction, and 1 time of measurement and reading in each week after construction.
The distance between the displacement monitoring stations at the deep part of the roadway is 200m, and the distance between two measuring points in the measuring stations is 20 m. The first station (the rightmost station) is 140m from the tangent eye.
(4) Roadway anchor rod stress monitoring method
In order to ensure the accuracy of monitoring the stress of the anchor rod (cable), the intrinsic safety type anchor rod nondestructive detector developed by China mining university is adopted to monitor the stress of the anchor rod (cable). The anchor bolt support is anchored in the surrounding rock of the roadway, so that the anchor bolt support is a concealed project. Due to the limits of theory and technical conditions, there must be areas of inadequate support. How to find the areas with insufficient support and control the occurrence of roof fall accidents to the maximum extent has very important significance. The method adopts a bolt support nondestructive testing technology, combines the data measured on the tunneling surface, and can predict the roof collapse dangerous area of the tunnel by using the evaluation of the bolt support state. The sampling rate of the roadway anchor rods is 3% -5%, and the minimum number of the detection anchor rods is 33.
(5) Roadway anchor cable stress monitoring method
And monitoring the stress of the anchor cable by adopting an MJ-40 type anchor rod (cable) dynamometer and evaluating the stability and the safety of the surrounding rock of the roadway. The dynamometer is installed at the tail part of the anchor cable, one anchor cable dynamometer is installed on the tunneling surface every 50m, and the anchor cable dynamometer monitors that the horizontal distance from the first measuring point to the tunneling surface is 10 m.
（1）CO2Fracturing embodiment
Through the research on the influence of CO2 fracturing on roof fall of a tunneling surface, namely the stress distribution rule and the fracture distribution range of surrounding rock, the following results are found: when 15 CO2 blasting tubes, namely the length of the fracturing tube is 60m, the influence radius of stress waves reaches 32m, the stress concentration phenomenon near the blasting tubes is obvious, and the coal body fracture expansion range is greatly increased. Under the action of 15 CO2 blasting tubes, the influence of coal body crack distribution reaches 29m, and the crack development degree is related to the arrangement of cracking holes. Therefore, a reasonable fracturing scheme needs to be designed according to the simulation result and the on-site engineering geological condition, so that the extraction is reasonable, and the roof collapse possibility is low.
2.1 fracturing hole and Pre-draw hole arrangement
The coal seam cracks are increased and the air permeability is improved by utilizing high-energy gas phase fracturing of carbon dioxide at the heading face head-on of a rubber belt in a 23 mining area 60m after the rubber belt is set in the mine, so that gas can be dissociated from the coal seam as soon as possible, and the purpose of controlling the gas is achieved. And constructing a gas extraction drill site, wherein the section of the drill site is a trapezoidal section, the inner width is 4m, the depth is 5m, an outer deflection angle of 45 degrees is formed with a center line, and the height is consistent with that of a driving roadway. The drilling field adopts stepping arrangement, the interval between the same sides is 120m, and the interval between the different sides is 60 m.
According to the fluctuation condition of the top and bottom plates, the diameter of the hole is 94mm while digging, the hole is expanded by 113mm, 6 holes are arranged in the hole site while digging, and the hole depth of No. 1-No. 6 is 140 m. The dip angle of the drill hole is consistent with the trend of the coal bed, and the dip angle can be adjusted according to the actual condition; the azimuth angles 1# -6 # drilling holes are 0-5 degrees respectively. Drilling hole opening height: 1#, 3#, 5# holes 1.8m, 2#, 4#, 6# holes 1.3 m. The distance between the drill holes in the same row is 0.6m, and the distance between the drill holes in the adjacent two rows in the same row is 0.2 m. As shown in fig. 5 and 7.
And (3) arranging cracking holes in the middle of the tunneling face along the natural inclination angle of the coal body every 60m of the tunneling face, wherein the designed depth is 60m, the diameter of a drilled hole is 115mm, and the number of the fracturing rods is 15 per hole. In order to avoid the damage of the coal body tunnel wall caused by the fracturing, a certain safety distance is required to be reserved. The fracture parameters are shown in figure 4.
2.2 gas relief hole arrangement
After the CO2 pre-splitting is completed, 4 gas releasing drill holes can be arranged at the part of the coal seam facing the belt downhill tunneling working face in order to release the gas in the free state in the coal seam as soon as possible and further extract a large amount of gas. The drilling parameters are shown in fig. 6, and the arrangement is shown in fig. 8-10.
2.3 analysis of gas extraction Effect
In order to evaluate the influence of the optimized fracturing scheme on the gas effect of the tunneling surface, in 2016, 12 months, in a section with the length of 1800m when the adhesive tape is set down, a gas extraction test is carried out on site. Wherein the No. 1 hole is a fracturing hole, the aperture is 115mm, and the depth of the hole is 60 m. The holes 2#, 3#, 4#, 5# and 6# are all pre-drainage holes in a gas drilling field, the hole diameter is 94mm, and the hole depth is 140 m. And the measured data are tabulated as shown in fig. 11, and a corresponding graph is plotted as shown in fig. 12.
1) And (4) gas flow of the drill holes before and after pre-splitting. As can be seen from the figure, the natural gas flow before the 1# fracturing hole is presplitting is already attenuated to 1.6L/min, and the flow is increased to 35L/min by implementing presplitting blasting; the flow of No. 2, No. 3 and No. 4 investigation holes adjacent to the blast hole is increased in different degrees, and the average flow is increased by 3.8-6.7 times; no. 5 and No. 6 drill holes far away from the blast hole have no influence on the gas flow rate by presplitting blasting.
Simultaneously, the decay of experimental back drilling gas flow also reduces by a wide margin, obtains drilling natural gas through natural gas flow fitting and gushes out the law before the experiment and be:
in the formula, q1 is the gas emission amount of the drilled hole under natural conditions, L/min, t is the self-gas-discharging time of the drilled hole, d.
After the presplitting blasting test, the rule of gas emission from the drilled hole is as follows:
test results show that after carbon dioxide deep hole presplitting blasting, the flow attenuation coefficient of gas in a drill hole is reduced from 0.6911 d-1 to 0.0528 d-1, the pore structure of coal in a cracking range is effectively improved, gas is enabled to be desorbed and discharged more easily, and gas extraction is enabled to be more sustainable.
2) And (4) the permeability coefficient of the coal bed before and after blasting. At present, the radial flow method proposed by Zhou Shining academy is widely adopted in China to measure the permeability coefficient of the coal seam. The original permeability coefficient of the No. 3 coal seam is 0.4793m2/(MPa2 d), after the pre-splitting blasting test is carried out, the permeability coefficient is 12.9643m2/(MPa2 d) which is improved by 26 times compared with the permeability coefficient before the test is obtained through calculation according to the measured data of the coal seam gas content, the gas pressure, the drill hole gas flow and the like in a test area.
3. Analysis of fracturing gas extraction effect of driving face
The rubber belt is driven down along the bottom plate of a No. 3 coal seam, the average gradient of a roadway is +3 degrees, the thickness of the coal seam is 5.32-6.15m, the maximum gas content of the coal seam is 9.7482m 3/t in the actual measurement in the driving process, and the firmness coefficient f of the coal seam is 0.47. The length of the tunnel is 1351m, and by 2016, 1, 31 days, the tunnel is dug in an accumulated manner of 995m, and the CO2 gas-phase fracturing technology is recycled from the beginning.
Analyzing and summarizing the fracturing effect from the aspects of the change curve of the gas concentration of the return air flow before and after fracturing, the unbalanced coefficient of the gas emission of the working face, the monthly early warning times, the monthly average daily footage, the monthly average tunneling speed and the like.
3.1 gas extraction concentration variation before and after fracturing
1 hole is pressed and fractured at the upper end of the adhesive tape in 2016, 11 and 9 days, and 6 holes are dug and drawn at the same time in the left drilling field. And on 20 days after 5 months, the average concentration of 6 holes is 52 percent, the average mixed flow is 1.43m3/min, and the average pure flow is 0.80m 3/min. The total extraction amount of 6 holes per day is 1074m3, the average daily yield of each hole is 214.8m3, and the average maximum daily yield of 6 holes is 2066m 3. The average ten thousand meter extraction speed is 13.17m 3/min. The maximum value of the pure gas extracted by ten thousand meters on the average of the driving face is 0.6951m3/(min ten thousand meters), which is increased by 19 times. The extraction amount is accumulated to be 4.4 ten thousand meters 3 in 41 days.
As can be seen from the extraction parameter trend graph of the adhesive tape down-hill head-on drill site and fig. 14, the concentration and the pure flow of 6 holes rapidly rise after fracturing, and then are in a relatively stable state; the tape starts to be tunneled in 11 months and 15 days, and then the concentration and the pure flow rate are rapidly reduced. And (4) tunneling the roadway in 11 months and 29 days, forming pressure relief belts at two sides of the roadway, and obviously improving the gas extraction effect but being lower than the previous data. According to statistics, the alternate tunneling frequency of the tunnel is increased from 20 days to 30 days, the tunneling speed is greatly increased, and the rapid tunneling of the tunneling working face is expected to be realized. And in the next stage, the gas-phase fracturing permeability-increasing rapid tunneling industrial test is performed in an enlarged mode, and the gas-phase fracturing permeability-increasing rapid tunneling process is realized.
3.2 gas emission uniformity analysis
Theoretically, CO2 gas-phase fracturing can eliminate possible gas bags in front of tunneling, so that gas in front of the head can be uniformly distributed and can be discharged at a constant speed, the phenomenon that the gas emission intensity of a working face is suddenly high and suddenly low is reduced, and the gas emission uniformity of the working face is improved to a certain extent.
The change condition of the working face gas emission intensity in a period of time can be intuitively reflected by the working face return air flow gas concentration change curve, and the gas emission unbalance coefficient (the ratio of the maximum gas emission amount to the average gas emission amount of the working face) is a physical quantity for representing the unevenness of the working face gas emission, so that the gas phase fracturing effect can be evaluated by analyzing the working face return air flow gas concentration change condition and the gas emission unbalance coefficient before and after gas phase fracturing in a contrast manner.
(1) Gas concentration change curve of return air flow
The change curves of the return air gas concentration in normal production months (2016, 11 and 2016, 12 months) corresponding to 2-month footage before and after CO2 fracturing of the adhesive tape downhill tunneling surface in the 23-mining area are respectively shown in FIG. 15 and FIG. 16. As can be seen from the figure, when the gas phase fracturing technology is not adopted, the maximum of the concentration of the return air flow gas is up to 0.52 percent within 1 day, and the lowest is up to 0.18 percent. The variation amplitude is relatively large and is basically more than 0.2 percent; after the gas phase fracturing technology is adopted circularly, the change range of the gas concentration is within 0.1 percent, and the change range of the gas concentration is reduced by 50 percent relatively.
3.3 coefficient of gas emission imbalance
The change curve of the imbalance coefficient of gas emission of the driving face under the adhesive tape is shown in fig. 17 from 10/25/2015 to 2016/12/2016. As can be seen from the graph, when the gas phase fracturing technology is not adopted, the fluctuation of the imbalance coefficient of gas emission of the working face is large and is basically about 1.65, and the coefficient is relatively large as a whole; after the gas-phase fracturing technology is adopted circularly, the emission unbalance coefficient is in a slow descending trend and is gradually stabilized to about 1.25, and the gas emission unbalance coefficient is relatively reduced by 24 percent.
3.4 tunnelling speed
Theoretically, after the tunneling head-on is subjected to gas-phase fracturing, the head-on coal body can be loosened, the permeability coefficient of the coal body is greatly increased in a short time, and the head-on gas is fully and quickly released in the period that the working face head-on is not produced, so that the residual gas content of the head-on coal body is reduced, the pressure of gas early warning caused by the fact that a large amount of gas is emitted in the period that the head-on.
The influence of gas-phase fracturing on the tunneling speed is evaluated by counting the tunneling monthly footage of the working face in a certain time before and after fracturing and calculating the average daily footage. However, the tunneling speed of the working face is related to a plurality of factors, such as the original gas content of the coal seam, production organization, mechanical failure and the like, and the plurality of factors cannot be studied one by one, and the monthly tunneling average speed is calculated by only taking the factors of head-on advanced construction and maintenance and leave-out into consideration so as to assist analysis.
The condition of the belt mountain descending tunneling face tunneling month by month is shown in fig. 18, wherein no fracturing measure is taken on the working face from 12 months to 2016 months, no advance probe hole is constructed at the head of the working face, and the head-on advance probe and gas phase fracturing measures are taken from 3 months to 12 months 2016. By comprehensively analyzing the graphs 18 and 19, the average monthly footage of the non-gas-phase fracturing area is 82 m/month, the average daily footage is 2.67m, and the average tunneling speed is 2.67 m/d. In a gas-phase fracturing area, the average monthly footage is 94.2 m/month, which is improved by 14.2 m/month; the average daily footage is 3.11m, which is improved by 0.44 m; the average tunneling speed is 4.17m/d, and is increased by 1.5 m/d; and the average daily footage and the average tunneling speed both tend to rise.
3.5 hectometer gas early warning times
The gas early warning times of the average tunneling of 100m of the roadway in the gas phase fracturing area and the non-fracturing area of the driving face under the adhesive tape are compared and analyzed as shown in the figure 20, and the gas early warning times of hundred meters under the adhesive tape in the non-fracturing area is 0.81; after the CO2 fracturing technology is adopted, the fracturing area with the hectometer gas early warning times is 0, and the gas early warning times are obviously reduced.
4. Advance grouting effect analysis of small guide pipe of tunneling working face
From the comparison results of fig. 21 to fig. 24: and after grouting, the displacement of the surrounding rock on the left side of the driving surface under the adhesive tape is greatly reduced. The monitoring points are distributed at the middle line position of the left side wall of the tunneling face, the simulation result shows that the stable displacement value of the point before grouting is 5.0cm, the stable displacement value of the point after grouting is 2.5cm, the deformation of the left side surrounding rock of the tunneling face cannot be continuously increased along with the time, the displacement of the left side wall of the tunneling face after advanced grouting by using the small guide pipe is reduced by about 50% compared with that before grouting, and the condition that the stability of the left side surrounding rock of the tunneling face can be effectively improved by grouting is shown. The numerical simulation result shows that the deformation condition of the surrounding rock of the driving face can be well improved after the small guide pipe is adopted for grouting, and the stability of the surrounding rock of the driving face is greatly improved.
5. Permanent support effect analysis of driving face
The adhesive tape in the 23 mining area is supported by high prestress yielding anchor rods, double-steel-bar joists, metal graticules and anchor cables in a combined mode, deformation of the top plate and the bottom plate of 3 sections and deformation of two sides of the top plate and the bottom plate are monitored for 2 months, and the monitoring result is shown in figure 25.
The field monitoring results shown in fig. 26 indicate that: after the CO2 fracturing technology is adopted, the crack development has large influence on the deformation of surrounding rocks of a roadway, and when the yielding anchor net cable combined support is not adopted, the sinking of a top plate of a tunneling surface is severe in the early stage. In the early 20 days, the increase trend is always shown, the increase amplitude is large, and relatively speaking, the top plate moving amount is smaller than the deformation amount of the two sides and the bottom plate; after the yielding anchor net cable is adopted for combined supporting when the section is observed for 20 days, the top plate is still in an increasing state in a short time, but the increasing amplitude is small, and the later stage is basically stable and stable at about 270mm, so that the production safety requirement is met; the moving amount and the bottom bulging amount of the two sides are larger than the deformation amount of the top plate, and the maximum deformation amount after stabilization is in a safety range. After the coal seam is cracked by CO2, the yielding anchor net cable support is adopted, namely a permanent support scheme, the surrounding rock of the tunneling face is well maintained, the effect is good, and roof fall is basically avoided.
6. Data collation and analysis
6.1 surface Displacement monitoring
The measured value of the surface displacement is obtained by observing the surface displacement of the adhesive tape downhill tunneling surface for 60 days, the maximum value of the subsidence of the roof of the tunneling surface is calculated and sorted as shown in a summary table in fig. 27, and a graph of the surface displacement of the monitoring section and the monitoring time is drawn by the monitoring data as shown in fig. 28.
As can be seen from fig. 27 and 28:
the sinking amount of the top plate of the tunneling face gradually increases along with the change of time and tends to be stable in about 55 days of observation; the maximum sinking amount of the top plate is 33.6mm, and the sinking rate of the top plate is not more than 0.56 mm/d.
Through observation result analysis, after temporary support is strengthened and permanent support parameters are optimized, the deformation of surrounding rocks of the tunneling surface is small, the surrounding rocks are stable, and the support effect is good.
6.2 roof delamination monitoring
In order to better understand the top plate separation condition of the tunneling surface and verify the supporting effect, 31-day separation monitoring is carried out on the tunneling surface under the adhesive tape, and as can be seen from fig. 29:
the total delamination value of the top plate of the tunneling surface is larger, but the total delamination value does not exceed 12 mm. After the temporary support technology and the permanent support technology are adopted, the maximum separation values inside and outside the anchoring area of the tunneling surface are respectively 3.5mm and 7.6mm, the rock stratum inside the anchoring area of the top plate and the rock stratum outside the anchoring area are basically stable, the total separation value of each measuring point is kept unchanged or changes slightly during monitoring, the change of the separation layer inside the anchoring area and the separation layer outside the anchoring area is generally less than 0.12mm/d, the deformation speeds of the separation layer inside and outside the anchoring area are approximately equivalent, and no roof collapse phenomenon is found during monitoring. The temporary supporting technology and the permanent supporting effect of the small duct grouting are obvious. The roof anchoring effect completely meets the supporting requirement, the integral performance of the supported roof rock stratum is good, the stability of the driving surface is good, and the supporting effect is good.
6.3 surrounding rock deep multi-point displacement monitoring
In order to deeply know the deep deformation characteristics of the surrounding rock of the tunneling surface and verify the supporting effect, the multipoint displacement monitoring of the surrounding rock is carried out on the tunneling surface of the adhesive tape going downhill for one month, the data of the observation section of the tunneling surface at a distance of 140m from the cutting hole are taken for comparative analysis, and the monitoring result shows that:
along with the increase of the depth of the surrounding rock of the tunneling surface, the deformation of the surrounding rock gradually increases, and the deformation of the surrounding rock at the top is larger than that of the surrounding rock at the upper part. The displacements of the shallow base point and the deep base point at the top of the tunneling surface are respectively 2.5mm and 7.3mm, the maximum displacements of the shallow base point and the deep base point at two sides are respectively 1.2mm and 3.6mm, the deformation of surrounding rocks is not more than 8mm, and the normal and safe production requirements are completely met. After the carbon dioxide presplitting, the small-conduit advanced grouting technology and the permanent support technology are adopted, the deformation speed of the shallow foundation and the deep foundation of the surrounding rock is approximately equal, and no roof fall or rib spalling phenomenon is found during the monitoring period. The roof fall control technology completely meets the supporting requirement, and after the roof fall control technology is supported, the surrounding rock of the driving face has good overall performance, the stability of the driving face is good, and the supporting effect is good.
6.4 analysis of anchor rod stress monitoring result
And carrying out nondestructive testing on the stress of 5 anchor rods in the middle of the left upper of the adhesive tape downhill tunneling surface and 6 anchor rods in the middle of the top of the adhesive tape downhill tunneling surface in the 23 mining area to obtain the measured data. Through the detection data, the bolting effect of the excavation face is excellent, and the requirements of normal and safe production are met.
6.5 analysis of anchor cable stress monitoring results
The stress of 10 anchor cables on the rubber belt downhill tunneling surface of the 23 mining area is monitored for 19 days in total, and the monitoring is carried out once every two days, so that the monitoring numerical value and the graph 30 show that: in the excavation face extraction process, the average stress of the anchor cables of the excavation face is larger, the maximum value of the stress of the anchor cables is 387.3KN, the minimum value of the stress of the anchor cables is 303KN, the anchor cable anchoring effect is better, and the supporting effect is good.
6.6 leading bearing pressure distribution
Six stress sensors are arranged on the rubber belt downhill tunneling surface of the 23 mining area in the field test, and the advanced supporting pressure change rule of the tunneling surface is obtained through observation and recording for 60 days. FIG. 31 is a graph showing the variation of observed data of each borehole stress meter with distance from the coal wall of the heading face. The face leading support pressure profile is characterized as shown in the profile table of figure 32.
From the above, the following conclusions can be drawn:
(1) the influence range of the advancing supporting pressure of the heading face is 0-25 m in front of the coal wall.
(2) The change is large from the stress peak value observed by a borehole stress meter, the peak value of the advanced supporting pressure of the heading face is averagely 4.56MPa, the initial stress is averagely 2.7MPa, and the stress concentration coefficient is 1.68.
7 summary of the invention
(1) The field measurement finds that: after the CO2 fracturing technology is adopted on the driving face of the adhesive tape going downhill, the fracture distribution range of the top coal is greatly increased, the penetration degree of the fractures is large, the integrity of the top plate of the driving face is not good, but the gas extraction content is greatly increased compared with the original gas extraction content. Through the on-site monitoring, the following results are found: the gas concentration variation range of the downward air return flow of the adhesive tape is reduced by 50% in the fracturing area compared with the non-fracturing area; the gas emission unbalance coefficient of the fracturing area is reduced by 24 percent compared with the non-fracturing area. The number of the hundred-meter gas early warning times of the belt downhill tunneling surface is reduced by 0.81. The average tunneling speed of the rubber belt downhill tunneling surface of the 23 mining area is increased by 1.5m/d, and the average daily footage of the roadway is increased by 0.44 m.
(2) Aiming at the influence of CO2 fracturing on stress and fracture expansion range of surrounding rock below the adhesive tape and combining with specific geological conditions of the normal village mine, a specific fracturing optimization scheme is provided, namely fracturing, pre-pumping and gas release holes. The specific parameters are as follows: the fracturing holes are arranged along the center line of the roadway, the length of the fracturing holes is 60m, the diameter of drilled holes is 115mm, the hole sealing depth is 12m, and the hole sealing pressure is 7-8 Mpa; the pre-pumping holes are arranged in gas drilling fields on two sides of the roadway, the length is 140m, the diameter of the drilled holes is 94mm, the distance between the drilled holes in the same row is 0.6m, and the distance between the drilled holes in the two adjacent rows in the same row is 0.2 m. After cracking, 4 gas release holes with the depth of 20m are additionally drilled. On the basis, the field pre-splitting is carried out on the gas extraction effect, and the result shows that: after the pre-splitting, the natural flow of the gas is greatly improved, and the air permeability of the coal bed is improved by 26 times.
(3) The small duct grouting technology is adopted to discover that: after grouting, the stable displacement value of the top plate is 2.5cm, and the displacement of the left lane side is reduced by about 50% compared with that before grouting, which shows that the stability of the surrounding rock of the driving face can be effectively improved by grouting. After the permanent support parameters are optimized, the top plate sinks and is stabilized to be about 270mm, and the production safety requirements are met; the moving amount and the bottom bulging amount of the two sides are larger than the deformation amount of the top plate, and the maximum deformation amount is in a safety range. The distribution range of the tunneling surface and the gas drilling field cracks is small, and the supporting effect is good.
(4) After the small-duct grouting technology is adopted and permanent parameters are optimized, the top plate of the heading face is maintained at a relatively stable stage, and the top coal caving control effect is good. The anchor rod and the anchor cable are in good stress state, the phenomenon of breakage is avoided, and the roof fall times and range are well reduced to be within the safety range. The comprehensive support technology has good surrounding rock deformation control effect on controlling roof fall of the tunneling surface of the large-section soft coal seam.
The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.
Claims (10)
1. A high gas coal roadway presplitting permeability-increasing industrial test method is characterized by comprising the following steps:
arranging monitoring devices for realizing roadway surface displacement monitoring, roadway roof separation monitoring, roadway surrounding rock deep multi-point displacement monitoring and anchor rod and/or anchor cable stress monitoring at set positions;
arranging fracturing holes at a driving face, arranging gas drilling fields at two sides of the driving face, arranging pre-pumping holes at the drilling fields, and carrying out CO (carbon monoxide) on the fracturing holes2Pre-splitting, and extracting gas from the pre-extraction hole;
performing advanced grouting on a small guide pipe on a driving working face;
and analyzing the gas extraction effect and the permanent support effect of the driving face before and after fracturing, and judging the rationality of related design parameters by combining the monitoring data acquired by the monitoring device.
2. The high gas coal roadway presplitting permeability improvement industrial test method according to claim 1, wherein the roadway surface displacement monitoring content comprises: the sinking amount of the top plate and the bottom plate, the bottom bulging amount and the moving close amount of the two sides.
3. The industrial test method for pre-splitting permeability increase of the high gas coal roadway according to claim 1, wherein the inclination angle of the drill hole of the pre-drainage hole is consistent with the coal seam trend, and the inclination angle is adjusted according to actual conditions.
4. The method for the industrial test of pre-splitting permeability of the high-gas coal roadway according to claim 1, wherein the drilling site is arranged in a stepping manner, and the spacing between the same sides is 110-130m, and the spacing between the opposite sides is 55-65 m.
5. The industrial test method for pre-splitting permeability of the high gas coal roadway according to claim 4, wherein a plurality of the pre-drainage holes are arranged at the same drilling site, the distance between the holes in the same row is 0.55-0.65m, and the distance between the holes in the two adjacent rows and the same row is 0.15-0.25 m.
6. The high gas coal roadway pre-splitting permeability-increasing industrial test method according to claim 4, wherein the fracturing holes are arranged along a natural inclination angle of a coal body in the middle of a heading face, and the design depth of the fracturing holes is the same as the interval distance between opposite sides of the drilling field.
7. The high gas coal roadway pre-splitting permeability-increasing industrial test method according to claim 1, wherein the fracturing holes are directional fracturing holes, namely wedge-shaped grooves are arranged on two sides of the fracturing holes in the horizontal direction.
8. The method for industrial testing of pre-splitting permeability of high gas coal roadway according to claim 1, wherein CO is to be treated2And after the pre-splitting is finished, arranging a gas release drill hole at the tunneling surface, and extracting gas from the gas release drill hole.
9. The high gas coal roadway presplitting permeability-increasing industrial test method according to claim 1, wherein the content of gas extraction effect analysis before and after fracturing comprises the following steps: the change rule of the gas flow of the drilled hole before and after fracturing, the permeability coefficient of the coal bed, the gas extraction concentration, the gas emission uniformity and the gas emission unbalance coefficient.
10. The industrial test method for pre-splitting permeability increase of the high gas coal roadway according to claim 1, wherein when the reasonability of the related design parameters is judged, analysis of the change rule of the tunneling speed of the roadway before and after fracturing and the pre-warning times of hectometers gas is further included.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811347511.5A CN109555502B (en) | 2018-11-13 | 2018-11-13 | Industrial test method for presplitting permeability increase of high-gas coal roadway |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811347511.5A CN109555502B (en) | 2018-11-13 | 2018-11-13 | Industrial test method for presplitting permeability increase of high-gas coal roadway |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109555502A CN109555502A (en) | 2019-04-02 |
| CN109555502B true CN109555502B (en) | 2021-04-06 |
Family
ID=65866329
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811347511.5A Active CN109555502B (en) | 2018-11-13 | 2018-11-13 | Industrial test method for presplitting permeability increase of high-gas coal roadway |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109555502B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111287787A (en) * | 2020-03-20 | 2020-06-16 | 华北科技学院 | Method for efficiently pumping and discharging gas through top plate crack expansion |
| CN113847075B (en) * | 2021-10-12 | 2023-11-10 | 河海大学 | Self-tapping type abdicating anchor rod for controlling large deformation of soft rock |
| CN115218808B (en) * | 2022-07-18 | 2023-07-14 | 太原理工大学 | Method and system for judging and early warning stability of surrounding rock along with excavation |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4114688A (en) * | 1977-12-05 | 1978-09-19 | In Situ Technology Inc. | Minimizing environmental effects in production and use of coal |
| CN101408106A (en) * | 2007-10-12 | 2009-04-15 | 中煤第三建设（集团）有限责任公司 | Small tube shed pre-grouting method |
| CN201396135Y (en) * | 2009-05-05 | 2010-02-03 | 中国科学院武汉岩土力学研究所 | Deep hole displacement measuring point fixing device |
| CN201696091U (en) * | 2010-03-05 | 2011-01-05 | 山东科大中天电子有限公司 | Mine ground pressure displacement monitoring system |
| WO2012092404A1 (en) * | 2010-12-28 | 2012-07-05 | Enis Ben M | Method and apparatus for using pressure cycling and cold liquid co2 for releasing natural gas from coal and shale formations |
| CN103233777A (en) * | 2013-05-17 | 2013-08-07 | 上海大屯能源股份有限公司 | Safe mine pressure monitoring method and device for roof |
| CN204552734U (en) * | 2015-04-17 | 2015-08-12 | 济宁矿业集团花园井田资源开发有限公司 | A kind of monitoring system measured for coal mine several data |
| CN106194244A (en) * | 2016-08-04 | 2016-12-07 | 重庆大学 | Lower permeability seam liquid phase CO2phase transformation fracturing is anti-reflection grid type gas pumping method |
| CN106837406A (en) * | 2016-11-28 | 2017-06-13 | 田成林 | A kind of coal seam with gas multistage anti-reflection method |
| CN107630711A (en) * | 2017-10-25 | 2018-01-26 | 中国矿业大学(北京) | A kind of roadway surrounding rock stress and the monitoring device and method of displacement |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6969123B2 (en) * | 2001-10-24 | 2005-11-29 | Shell Oil Company | Upgrading and mining of coal |
-
2018
- 2018-11-13 CN CN201811347511.5A patent/CN109555502B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4114688A (en) * | 1977-12-05 | 1978-09-19 | In Situ Technology Inc. | Minimizing environmental effects in production and use of coal |
| CN101408106A (en) * | 2007-10-12 | 2009-04-15 | 中煤第三建设（集团）有限责任公司 | Small tube shed pre-grouting method |
| CN201396135Y (en) * | 2009-05-05 | 2010-02-03 | 中国科学院武汉岩土力学研究所 | Deep hole displacement measuring point fixing device |
| CN201696091U (en) * | 2010-03-05 | 2011-01-05 | 山东科大中天电子有限公司 | Mine ground pressure displacement monitoring system |
| WO2012092404A1 (en) * | 2010-12-28 | 2012-07-05 | Enis Ben M | Method and apparatus for using pressure cycling and cold liquid co2 for releasing natural gas from coal and shale formations |
| CN103233777A (en) * | 2013-05-17 | 2013-08-07 | 上海大屯能源股份有限公司 | Safe mine pressure monitoring method and device for roof |
| CN204552734U (en) * | 2015-04-17 | 2015-08-12 | 济宁矿业集团花园井田资源开发有限公司 | A kind of monitoring system measured for coal mine several data |
| CN106194244A (en) * | 2016-08-04 | 2016-12-07 | 重庆大学 | Lower permeability seam liquid phase CO2phase transformation fracturing is anti-reflection grid type gas pumping method |
| CN106837406A (en) * | 2016-11-28 | 2017-06-13 | 田成林 | A kind of coal seam with gas multistage anti-reflection method |
| CN107630711A (en) * | 2017-10-25 | 2018-01-26 | 中国矿业大学(北京) | A kind of roadway surrounding rock stress and the monitoring device and method of displacement |
Non-Patent Citations (1)
| Title |
|---|
| 高瓦斯掘进工作面深孔控制预裂技术;张羽;《煤矿安全》;20161231;第47卷(第12期);57-60 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109555502A (en) | 2019-04-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Zhang et al. | Ground response of a gob-side entry in a longwall panel extracting 17 m-thick coal seam: a case study | |
| Li et al. | In situ monitoring of rockburst nucleation and evolution in the deeply buried tunnels of Jinping II hydropower station | |
| CN109611143A (en) | The multi-parameter integrated monitoring system of top plate hydrofracturing and fracturing effect method of discrimination | |
| CN109555502B (en) | Industrial test method for presplitting permeability increase of high-gas coal roadway | |
| CN209761499U (en) | Roof hydraulic fracturing multi-parameter comprehensive monitoring system | |
| Wang et al. | Practices on rockburst prevention and control in headrace tunnels of Jinping II hydropower station | |
| Huang et al. | Field investigation into directional hydraulic fracturing for hard roof in Tashan Coal Mine | |
| CN111460666B (en) | Rock burst risk prediction method for typical rock burst mine | |
| CN109798106A (en) | A kind of prediction technique and control measure of bump risk | |
| CN103422847A (en) | Gas extraction method based on mining-induced fracture circular rectangular half-space zone | |
| CN109236353A (en) | A kind of exposed coal protrusion-dispelling construction method in high methane Tunnel Passing coal seam | |
| Liu et al. | A case study of collapses at the Yangshan tunnel of the Coal Transportation Channel from the Western Inner Mongolia to the Central China | |
| CN110792450A (en) | Method for determining advanced support of grouting anchor cable | |
| CN114251103B (en) | Directional joint-cutting fracturing roof main roadway scour-prevention roadway-protecting method and safe mining method | |
| CN114397421B (en) | Mining coal seam floor damage depth monitoring method | |
| CN110579194B (en) | On-site testing method and application of fracture position of lateral basic roof rock beam of gob-side roadway | |
| CN111677514B (en) | Roof weakening method | |
| CN112378769A (en) | Hydraulic pre-fracturing parameter determination method | |
| CN109598029A (en) | One kind being applied to high methane coal road CO2The design method of high pressure gas fracturing | |
| Li et al. | Failure analysis of deep composite roof roadway and support optimization of anchor cable parameters | |
| CN105698853B (en) | The detection method of country rock Effect of Bolt-grouting Support during a kind of working face extraction | |
| CN114483163A (en) | Gas extraction method | |
| Gao et al. | Study on dynamic behavior law and microseismic monitoring in stoping process of roadway with high gas and wide coal pillar | |
| CN117027802B (en) | Method for preventing and controlling coal mine rock burst in advance in ground horizontal well segmented fracturing area | |
| Song et al. | A method for determining the overburden failure height of coal mining based on the change of drilling speed and the leakage of sectional water injection in underground upward bolehole |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |