CN115263305B - Deep slotting pressure relief and impact prevention method for rock burst coal seam drilling - Google Patents
Deep slotting pressure relief and impact prevention method for rock burst coal seam drilling Download PDFInfo
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- CN115263305B CN115263305B CN202210895578.2A CN202210895578A CN115263305B CN 115263305 B CN115263305 B CN 115263305B CN 202210895578 A CN202210895578 A CN 202210895578A CN 115263305 B CN115263305 B CN 115263305B
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- 239000003245 coal Substances 0.000 title claims abstract description 111
- 238000005553 drilling Methods 0.000 title claims abstract description 107
- 239000011435 rock Substances 0.000 title claims abstract description 33
- 238000000034 method Methods 0.000 title claims abstract description 32
- 230000002265 prevention Effects 0.000 title claims abstract description 19
- 238000010276 construction Methods 0.000 claims abstract description 30
- 238000005520 cutting process Methods 0.000 claims description 63
- 238000011156 evaluation Methods 0.000 claims description 9
- 230000002035 prolonged effect Effects 0.000 claims description 8
- 238000009826 distribution Methods 0.000 claims description 7
- 238000012544 monitoring process Methods 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 20
- 230000000694 effects Effects 0.000 description 4
- 238000005065 mining Methods 0.000 description 4
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 239000002817 coal dust Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
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- 238000004880 explosion Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 230000001550 time effect Effects 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C41/00—Methods of underground or surface mining; Layouts therefor
- E21C41/16—Methods of underground mining; Layouts therefor
- E21C41/18—Methods of underground mining; Layouts therefor for brown or hard coal
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21C—MINING OR QUARRYING
- E21C39/00—Devices for testing in situ the hardness or other properties of minerals, e.g. for giving information as to the selection of suitable mining tools
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Abstract
The application relates to a deep slotting pressure relief and impact prevention method for rock burst coal seam drilling, which comprises the following steps: determining a region range to be relieved; determining construction parameters of pressure relief drilling holes based on the range of the area to be relieved, and determining a slotting construction scheme based on the intensity of coal bodies in the impact dangerous area; in the slotting construction scheme, umbrella-shaped pressure relief slots are implemented in the pressure relief drilling holes to relieve pressure. According to the application, umbrella-shaped cracks are arranged in the pressure relief drilling holes, so that the large-range pressure relief of the deep high-stress coal body can be realized under the condition of increasing the drilling space, and the purposes of low-density low-strength pressure relief of the shallow coal body and high-density high-strength full pressure relief of the deep coal body are achieved.
Description
Technical Field
The application belongs to the technical field of pressure relief and impact prevention of rock burst coal beds, and particularly relates to a deep slotting pressure relief and impact prevention method for rock burst coal bed drilling.
Background
Rock burst is a typical mine dynamic phenomenon and has great hazard. The dynamic phenomenon instantaneously releases a large amount of elastic deformation accumulated in the coal rock mass in a sharp and violent mode, so that the coal rock mass is damaged and generates strong vibration, and the dynamic throws the broken coal rock into a roadway mining space, and makes strong sound, so that equipment damage, roadway damage, casualties and the like are caused. 144 rock burst mines are identified and confirmed in production mines in China by 2021, at least 195 main coal seams are involved, the coal yield of the rock burst mines accounts for about 12% of the total coal yield in China, and the rock burst has become a main limiting factor for limiting the safe and efficient exploitation of deep coal resources.
Aiming at the coal seam with rock burst danger, the pressure relief control method mainly comprises the steps of coal body large-diameter drilling pressure relief, coal seam water injection and coal body pressure relief blasting. The pressure relief and danger relief time effect of coal seam water injection is poor, the pressure relief and explosion of the coal body have potential safety hazards, and the pressure relief of the large-diameter drilling of the coal body is a main pressure relief and danger relief technical mode of rock burst coal seam due to the simplicity of construction. The smaller the distance between the pressure relief holes of the large-diameter holes of the coal body is, the larger the diameter of the holes is, and the better the effect is. However, because the aperture of the pressure relief of the large-diameter drilling holes of the coal body is kept unchanged from shallow to deep, the high-density large-diameter drilling holes often damage the coal body at the shallow part of the roadway side, so that the anchor rod support system at the roadway side is invalid, the deformation of surrounding rocks of the roadway is aggravated, and the normal use of the roadway is affected. According to the mine pressure theory, the shallow coal body at the roadway side part is in a plastic state and does not have the condition of accumulating elastic strain energy, while the deep coal body is in a high-stress and elastic energy accumulating area, so that the pressure relief density and strength of the shallow coal body at the roadway side part can be reduced, and the pressure relief range and strength of the deep coal body are increased.
Disclosure of Invention
In view of the analysis, the invention aims to provide a deep slotting pressure relief and anti-impact method for rock burst coal seam drilling, which is used for solving the problem that the existing pressure relief control method cannot effectively realize deep coal body pressure relief.
The purpose of the invention is realized in the following way:
a rock burst coal seam drilling deep slotting pressure relief and impact prevention method comprises the following steps:
determining a region range to be relieved;
determining construction parameters of the pressure relief drilling based on the range to be relieved, and determining a slotting construction scheme based on the coal strength of the impact dangerous area; in the slotting construction scheme, umbrella-shaped pressure relief slots are implemented in the pressure relief drilling holes to relieve pressure.
Further, before determining to implement the pressure relief range, further comprising: and determining the pressure relief time based on the grade evaluation result of the impact dangerous area in the target area.
Further, the pressure relief engineering opportunity is determined according to the following conditions:
For a strong impact hazard zone, the pressure relief opportunity is: when the distance between the strong impact dangerous area and the working surface is not less than 300m, and the working surface is advanced for 60-70 days, the pressure relief engineering is started to be implemented;
for medium impact hazard zones, the pressure relief opportunities are: when the medium impact dangerous area is 200-300m away from the working surface, and the working surface is advanced for 50-60 days, the pressure relief engineering is started to be implemented;
For a weak impact hazard zone, the pressure relief opportunities are: and when the weak impact dangerous area is 100-200m away from the working surface, and the working surface is advanced for 30-40 days, the pressure relief engineering is started.
Further, the step of determining the range of the area to be relieved is as follows:
carrying out stress monitoring and drilling cuttings monitoring in a coal seam working face roadway with impact danger, obtaining a coal body supporting pressure distribution rule according to monitored data, drawing a supporting pressure curve, and determining the position of a supporting pressure peak value and the distance L between the peak value and the roadway side, wherein the range L to be relieved, in which pressure relief is required, is as follows:
Where l is the distance from the peak of the supporting pressure to the roadway side, and m.
Further, the construction parameters of the pressure relief drilling holes comprise depth, aperture and spacing of the pressure relief drilling holes; according to the grade evaluation result of the impact dangerous area, the distance D, the depth H and the aperture R of the pressure relief drilling holes are determined, and the method specifically comprises the following steps:
areas of high impact risk: r is less than or equal to D and less than 1.5r, R is less than or equal to 42mm, H =max (l+10, 20) m;
Moderate impact hazard zone: d is more than or equal to 1.5r and less than or equal to 2.0r, R is more than or equal to 2 r 65mm, h=max (l+5, 15) m;
area of weak impact hazard: d is 2.0r < 4.0r, r is 65mm, h=max (l, 15) m;
Wherein R is the average length of the crack, D is the distance between the pressure relief drilling holes, H is the depth of the pressure relief drilling holes, and R is the aperture of the pressure relief drilling holes.
Further, before implementing the umbrella-shaped pressure relief slit in the pressure relief borehole, the method further comprises: acquiring the coal body strength R c of the impact danger zone, and determining the diameter of a nozzle for performing slotting according to the following conditions based on the acquired coal body strength R c of the impact danger zone
When R c is less than or equal to 10MPa, phi is more than or equal to 3.0mm;
when R c is more than 10 and less than 15MPa, phi is more than or equal to 2.0 and less than 3.0mm;
When R c is more than or equal to 15MPa, phi is less than or equal to 2.0mm.
Further, during slotting construction, a plurality of groups of umbrella-shaped pressure relief slots are sequentially constructed from inside to outside in the pressure relief drilling holes by using cutting equipment, each group of umbrella-shaped pressure relief slots comprises 8-12 symmetrical slots, and the lengths of the slots are controlled by controlling the cutting time in the implementation process.
Further, when the coalbed occurrence of the area to be relieved is stable and no occurrence changes, the lengths of the plurality of cracks are the same;
when the area to be relieved is close to the fault structure, the crack length of one side close to the fault structure is longer than that of one side far away from the fault structure;
When the area to be relieved is close to the buckling structure, the length of the crack on the side close to the shaft part of the buckling structure is longer than that on the side far away from the shaft part of the buckling structure.
Further, when the coalbed occurrence in the area to be relieved is stable and no occurrence changes, the cutting time of all cracks is T, and the cutting pressure is P;
If the fault fall is greater than the thickness of the coal seam, the cutting time is prolonged to T 1 and the cutting pressure is increased to P 1,T1＝1.3T-1.5T,P1 =1.2P-1.5P near one side of the fault;
If the fault fall is smaller than the thickness of the coal seam, the cutting time is prolonged to be T 3 and the cutting pressure is increased to be P 3,T3＝1.8-2T,P3 =1.8P-2P close to one side of the fault;
If the area to be relieved is close to one side of the anticline shaft part, the cutting time is prolonged to T 5, and the pressure is increased to P 5,T5＝1.5T,P5 =1.2P-1.5P;
If the area to be relieved is near one side of the syncline portion, the cutting time is prolonged to T 7 and the pressure is increased to P 7,T7＝2T,P7 =1.2p-1.5p.
Further, the distance Deltal between two adjacent umbrella-shaped pressure relief joints in the pressure relief drilling hole is determined according to the following formula:
Impact risk is evaluated as a region of strong impact risk: Δl is less than or equal to 1.0m;
impact risk was evaluated as a region of moderate impact risk: Δl is more than 1.0 and less than or equal to 2.0m;
impact risk was evaluated as a region of weak impact risk: Δl is more than 2.0 and less than or equal to 3.0m.
Further, after the umbrella-shaped pressure relief joint is completed, water injection is continued for 30min by adopting high-pressure water jet flow in the pressure relief drilling hole.
Compared with the prior art, the invention has at least one of the following beneficial effects:
a) According to the deep slotting pressure relief and impact prevention method for rock burst coal seam drilling, the time for implementing pressure relief is determined according to the impact risk evaluation result; determining the initial position and range of umbrella-shaped pressure relief according to the peak position of the supporting pressure; according to the uniaxial compressive strength of the coal body, determining parameters of a high-pressure water jet nozzle, and determining an umbrella-shaped slotting arrangement form; based on the in-hole cut fracture length, a pressure relief borehole spacing is determined. The high-pressure water jet is utilized to cut a seam according to a certain circumferential angle at the deep part of the coal body in the pressure relief drilling hole of the coal bed with small aperture, umbrella-shaped cracks are formed, and the purposes of realizing large-scale pressure relief of the deep high-stress coal body, low-density low-strength pressure relief of the shallow coal body and high-density high-strength full pressure relief of the deep coal body can be achieved under the condition of increasing the distance between the drilling holes.
B) The deep slotting pressure relief and impact prevention method for rock burst coal seam drilling provided by the invention not only can ensure the stability of the tunnel anchor bolt supporting structure, but also can realize the accurate pressure relief of a high-stress impact dangerous area, thereby achieving the effects of dual purposes of impact prevention and roadway protection and twice the effort.
Drawings
In order to more clearly illustrate the embodiments of the present description or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the embodiments of the present description, and other drawings may be obtained according to these drawings for a person having ordinary skill in the art.
FIG. 1 is a flow chart of a deep slotting pressure relief and anti-flushing method for rock burst coal seam drilling provided by the invention;
FIG. 2 is a schematic plan layout view of a deep slotting pressure relief and impact prevention method for rock burst coal seam drilling provided by the invention;
FIG. 3 is a schematic view in section A-A of the vertical bore of FIG. 2; ;
FIG. 4 is a schematic view in section B-B of the parallel borehole of FIG. 2;
FIG. 5 is a schematic view of umbrella-shaped slits as the area to be relieved approaches the fault formation.
Reference numerals:
1-goaf; 2-working surface; 3-lane sides; 4-pressure relief drilling; 5-umbrella-shaped pressure relief joint; 6-coal seam; 7-top plate; 8-a bottom plate; 9-fault construction.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
For the purpose of facilitating an understanding of the embodiments of the present application, reference will now be made to the following description of specific embodiments, taken in conjunction with the accompanying drawings, which are not intended to limit the embodiments of the application.
In describing embodiments of the present invention, it should be noted that, unless explicitly stated and limited otherwise, the term "coupled" should be interpreted broadly, for example, as being fixedly coupled, as being detachably coupled, as being integrally coupled, as being mechanically coupled, as being electrically coupled, as being directly coupled, as being indirectly coupled via an intermediate medium. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
The terms "top," "bottom," "above … …," "below," and "on … …" are used throughout to describe relative positions with respect to components of the device, such as the relative positions of the top and bottom substrates inside the device. It will be appreciated that the devices are versatile, irrespective of their orientation in space.
Example 1
In one embodiment of the invention, as shown in fig. 1 to 4, a deep slotting pressure relief and impact prevention method for rock burst coal seam drilling is disclosed, and umbrella-shaped pressure relief slots 5 are implemented in pressure relief drilling holes 4 for pressure relief, and the method comprises the following steps:
step S1: and determining the pressure relief time based on the grade evaluation result of the impact dangerous area in the target area.
And carrying out impact risk evaluation in the mining area, dividing the mining area into a strong impact risk area, a medium impact risk area and a weak impact risk area according to impact risk grades, and determining the time for implementing the pressure relief engineering according to the impact risk evaluation result of the mining area. When determining the pressure relief engineering occasion to implement, the pressure relief engineering occasion is determined according to the following conditions:
for a strong impact hazard zone, the pressure relief opportunity is: when the distance between the strong impact dangerous area and the working surface 2 is not less than 300m, and the working surface is advanced for 60-70 days, the pressure relief engineering is started to be implemented;
for medium impact hazard zones, the pressure relief opportunities are: when the distance between the medium impact dangerous area and the working surface 2 is 200-300m, and the working surface is advanced for 50-60 days, the pressure relief engineering is started to be implemented;
for a weak impact hazard zone, the pressure relief opportunities are: the pressure relief engineering is started when the weak impact dangerous area is 100-200m away from the working surface 2 and the working surface is advanced for 30-40 days.
The right side is a goaf 1 as shown in fig. 2, and the implementation sequence of the pressure relief engineering is as follows: and constructing sequentially from the working face 2 to the stoping line direction.
Step S2: and determining a range to be relieved, which needs to be relieved.
Specifically, stress monitoring and drilling cuttings monitoring are carried out in a roadway of a coal seam working face with impact danger, a coal body supporting pressure distribution rule is obtained according to monitored data, a supporting pressure curve is drawn, the position of a supporting pressure peak value and the distance L between the peak value and the roadway side 3 are determined, and the range L of a to-be-relieved area needing to implement pressure relief is as follows:
wherein l is the distance from the peak of the supporting pressure to the roadway side (3), and m.
That is, ① is carried out forward from the (l-5) m position by taking the opening of the pressure relief borehole 4 of the roadway side 3 as the origin when the supporting pressure peak value is greater than or equal to 10m from the roadway side 3, and the total is 10m; ② When the supporting pressure peak value is more than 5m and less than 10m from the roadway side 3, taking the opening of the pressure relief drilling hole 4 of the roadway side 3 as an origin, starting to implement forward at the position of the internal stress peak point of the drilling hole, and adding up to 5m; ③ When the distance between the supporting pressure peak and the roadway wall 3 is smaller than 5m, only the pressure relief drilling 4 is adopted for pressure relief, and umbrella-shaped slotting is not implemented in the holes.
Step S3: determining construction parameters of the pressure relief drilling holes 4 based on the range to be relieved, and determining a slotting construction scheme based on the coal strength of the impact dangerous area; the pressure relief is performed by implementing an umbrella-shaped relief slit 5 in the relief borehole 4.
Step S3-1: and determining construction parameters of the pressure relief drilling holes 4, wherein the construction parameters of the pressure relief drilling holes 4 comprise parameters such as hole depth, aperture, inclination angle, spacing, final hole position and the like of the pressure relief drilling holes 4. When the coal seam 6 is drilled, at the initial position of the designed construction, firstly, the pressure relief drilling 4 of the coal seam 6 is implemented to the final hole position, and the drilling machine for implementing the pressure relief drilling 4 of the coal seam 6 moves forward to continue implementing the pressure relief drilling 4 of the next coal seam 6 until the construction of the pressure relief drilling 4 at all preset positions is completed.
According to the grade evaluation result of the impact dangerous area, the distance D, the depth H and the aperture R of the pressure relief drilling holes 4 are determined, and the specific steps are as follows:
① Areas of high impact risk: r is less than or equal to D and less than 1.5r, R is less than or equal to 42mm, H =max (l+10, 20) m;
② Moderate impact hazard zone: d is more than or equal to 1.5r and less than or equal to 2.0r, R is more than or equal to 2 r 65mm, h=max (l+5, 15) m;
③ Area of weak impact hazard: d is 2.0r < 4.0r, r is 65mm, h=max (l, 15) m.
Where R is the average length of the cracks cut in the pressure relief drilling holes 4, D is the spacing of the pressure relief drilling holes 4, H is the depth of the pressure relief drilling holes 4, and R is the aperture of the pressure relief drilling holes 4.
The depth parameter of the pressure relief drilling 4 simultaneously meets the requirements of the position and the range of the umbrella-shaped pressure relief joint 5.
Coal seam 6 pressure relief borehole 4 the inclination angle determination scheme is as follows: the pressure relief drilling 4 of the coal bed is perpendicular to the roadway trend, the open pore is positioned in the middle of the coal bed 6, and the distance between the top plate 7 and the bottom plate 8 of the coal bed 6 is not less than 1.5m, and the inclination angle of the pressure relief drilling 4 is parallel to the inclination angle of the coal bed 6.
The existing coal seam pressure relief uses large-diameter drilling pressure relief, the diameter of the pressure relief drilling hole is larger than 100mm, the diameter of the pressure relief drilling hole from the coal wall to the coal body is unchanged, but the power of a drilling machine for constructing the large-diameter drilling hole is large, and the hydraulic drilling machine is usually a hydraulic drilling machine, has large volume and is limited by a limited space in a roadway of a downhole working surface, and the large-volume drilling machine is inconvenient to move and operate. The embodiment adopts the pressure relief drilling hole with small aperture (the diameter of the pressure relief drilling hole is not more than 65 mm), the used drilling machine is small in size, the mobile construction operation is flexible, the hole expansion can be carried out in the area with high internal stress of the coal body, the problem that the large drilling machine cannot enter is solved, the influence on the anchor net supporting structure in the shallow coal wall can be reduced, and the damage instability of the coal wall caused by the failure of the anchor net supporting in the coal wall is avoided.
S3-2, acquiring the intensity of the coal body of the impact dangerous area, and determining the slotting parameters and the construction process based on the acquired intensity of the coal body of the impact dangerous area.
Specifically, the uniaxial compressive strength R c of the coal can be measured according to national standard GB/T23561.7-2009; the coal umbrella-shaped pressure relief seam 5 in the pressure relief drilling hole 4 is realized by adopting high-pressure water jet, the high-pressure water jet is sprayed out by double-nozzle drill bits, and the double nozzles are distributed on two sides of the drill bits and form 180 degrees with the connecting line of the center point of the drill bits.
The nozzle diameter selection is determined according to the following formula:
① When the uniaxial compressive strength R c of the coal body in the cutting area is less than or equal to 10MPa, the diameter phi of the nozzle is more than or equal to 3.0mm, and the nozzle with the diameter phi of 3.0mm is preferred;
② When the uniaxial compressive strength of the coal body in the cutting area is more than 10 and less than 15MPa, the diameter phi of the nozzle is more than or equal to 2.0 and less than 3.0mm, and the nozzle with the diameter phi of 2.5mm is preferred;
③ When the uniaxial compressive strength R c of the coal body in the cutting area is more than or equal to 15MPa, the diameter phi of the nozzle is less than or equal to 2.0mm, and the nozzle with the diameter phi of 2.0mm is preferred.
In step S3-2, during the slit arrangement construction, a plurality of groups of umbrella-shaped pressure relief slits 5 are sequentially constructed from inside to outside in the pressure relief borehole 4 by using cutting equipment. The umbrella-shaped pressure relief slits refer to multiple slits with different angles at the same position in the pressure relief drilling hole, and the multiple slits are in radial umbrella-shaped structures in the pressure relief drilling hole, as shown in fig. 4 to 5.
The drilling machine with the double-nozzle high-pressure water jet drill bit completes the umbrella-shaped pressure relief slit 5 by utilizing the high-pressure water jet in the completed pressure relief drill hole 4. Specifically, a straight-line-distributed double-nozzle high-pressure water jet drill bit is adopted, two cracks are cut at one time, a drill rod is rotated after cutting is completed, the rotation angle is 30-45 degrees, cutting is continued, 8-12 cracks are formed in the same position in the pressure relief drilling hole 4 after repeated rotation cutting for many times, and the length of the cracks can be controlled by controlling the cutting time. For example, after cutting, the same position of 8 cracks in the pressure relief drilling holes is 1 group of umbrella-shaped pressure relief joints 5, and after cutting, holes are washed by high-pressure water flow, and a plurality of groups of umbrella-shaped pressure relief joints 5 in the holes adopt a backward implementation mode, namely, firstly, the pressure relief drilling holes 4 of the coal bed 6 are implemented to the positions of the bottoms of the holes, after 1 group of cutting is completed, drill rods are withdrawn outwards from the pressure relief drilling holes 4, and construction of the umbrella-shaped pressure relief joints 5 in the next group of pressure relief drilling holes 4 is implemented according to the determined group spacing until the construction of the designed group number of umbrella-shaped pressure relief joints 5 is completed.
During the crack implementation, the length of the crack is controlled by controlling the cutting time. Specifically, the parameters (nozzle diameter) of the double nozzles can be controlled to realize the difference of the water pressure, the flow velocity and the flow rate of high-pressure water sprayed out from two sides, and the difference of the lengths of cracks at two sides. Or in the area needing to implement asymmetric slotting, two-round slotting is carried out, symmetrical cracks are firstly cut, then the two-round slotting is carried out by replacing with a large nozzle or plugging one nozzle, and the second-round slotting is carried out, at the moment, only one side is cut, so that the purposes of long one crack and short one side crack are realized.
Considering that the occurrence state of the coal seam and the formation structure condition of the area to be depressurized can influence the depressurization effect, in the slotting construction process of each group, the slotting scheme is formulated in a targeted manner aiming at different geological structure conditions. Taking 8 cracks in each group as an example, the length parameters of the 8 cracks at the same position of the pressure relief drilling hole 4 are determined according to the following principles:
① When the coal seam occurrence in the area to be relieved is stable and no occurrence changes, 8 cracks are symmetrical and have the same length, and when the construction is carried out, the cutting time and the pressure of the 8 cracks are the same, and the cutting time of all the cracks is T and the cutting pressure is P;
② When the region to be relieved is close to the fault structure 9, as shown in fig. 5, the crack length on the side close to the fault structure 9 is longer than that on the side far from the fault structure. Further, according to the relation between the fault throw and the thickness of the coal seam, the following two conditions are adopted:
(2.1) if the fault fall is greater than the thickness of the coal seam, approaching one side of the fault, prolonging the cutting time to T 1, increasing the cutting pressure to P 1, wherein the cutting time is 1.3-1.5 times of that of the non-fault side, and increasing the cutting pressure by 1.2-1.5 times, namely T 1＝1.3T-1.5T,P1 =1.2P-1.5P; whereas the cutting time T 2 =t, the cutting pressure P 2 =p of the side fracture far from the fault; the crack length near one side of the fault is larger than that of the cracks in other directions, asymmetric crack distribution is formed, and after the crack is cut to the fault plane, cutting is stopped;
(2.2) if the fault fall is smaller than the thickness of the coal seam, approaching one side of the fault, prolonging the cutting time to T 3, increasing the cutting pressure to P 3, wherein the cutting time T 3 is 1.8-2 times of that of the non-fault side, and increasing the cutting pressure by 1.2-1.5 times, namely T 3＝1.8-2T,P3 = 1.8P-2P; whereas the cutting time T 4 =t, the cutting pressure P 4 =p of the side fracture far from the fault. According to the scheme, the crack length at one side close to the fault is larger than that of cracks in other directions, asymmetric crack distribution is formed, the cracks continue to be cut after being cut to the fault surface, the fault surface penetrates through the fault at 90 DEG perpendicular to the fault surface, and penetrating pressure relief of the fault surface is achieved. Because the horizontal stress of the coal body near the fault is high, the crack is cut by using the crack construction scheme, the length of the cut crack is increased, and the horizontal stress of the fault plane can be reduced; after the cutting is carried out to the fault surface, a part of high-pressure water enters the fault surface, so that the friction force of the fault surface is reduced, the energy released by fault sliding is reduced, and the pressure relief effect is improved; the fracture passes through the fault surface, so that the integrity of the fault surface can be effectively damaged, and the energy accumulated by the fault is reduced.
③ When the area to be relieved is close to the buckling structure, the length of the crack on the side close to the shaft part of the buckling structure is longer than that on the side far away from the shaft part of the buckling structure. Further, according to the difference between the syncline configuration and the anticline configuration, the following two cases are further divided:
(3.1) if the area to be relieved is close to one side of the anticline shaft part, prolonging the cutting time to T 5 and increasing the pressure to P 5, wherein the cutting time T 5 is 1.5 times of one side far away from the anticline shaft part, and the cutting pressure crack is increased by 1.2-1.5 times, namely T 5＝1.5T,P5 =1.2P-1.5P; and cutting time T 6 =t, cutting pressure P 6 =p of the crack on the side far from the anticline shaft. The crack length at one side close to the anticline shaft part is longer than that of cracks in other directions, so that asymmetric crack distribution is formed;
(3.2) if the area to be relieved is close to one side of the syncline shaft, prolonging the cutting time to T 7 and increasing the pressure to P 7, wherein the cutting time T 7 is 2.0 times that of one side far away from the anticline shaft, and the cutting pressure crack is increased by 1.2-1.5 times, namely T 7＝2T,P7 =1.2P-1.5P; and cutting time T 8 =t, cutting pressure P 8 =p of the slit on the side away from the syncline portion. The crack length at one side close to the syncline shaft part is longer than that of the cracks in other directions, so that asymmetric crack distribution is formed. Because the buckling shaft part, especially the syncline shaft part, the horizontal stress is concentrated, and the coal seam is more compact under the action of horizontal extrusion, the crack is formed by utilizing the crack construction scheme, and the space for releasing the horizontal stress and the deformation is formed by cutting the crack, so that the aim of releasing pressure and energy is fulfilled.
In this embodiment, the distance Δl between two adjacent umbrella-shaped pressure relief slits 5 in the pressure relief borehole 4 is determined as follows:
① Impact risk is evaluated as a region of strong impact risk: Δl is less than or equal to 1.0m;
② Impact risk was evaluated as a region of moderate impact risk: Δl is more than 1.0 and less than or equal to 2.0m;
③ Impact risk was evaluated as a region of weak impact risk: Δl is more than 2.0 and less than or equal to 3.0m.
Further, after the umbrella-shaped pressure relief joint 5 is completed, water is continuously injected into the pressure relief drilling hole 4 by adopting high-pressure water jet flow for 30min, so that coal dust in the pressure relief drilling hole is further removed, and the coal body is wetted and softened.
Compared with the prior art, the deep slotting pressure relief and impact prevention method for the rock burst coal seam drilling is a pressure relief and impact prevention technical method for slitting the deep part of the impact dangerous coal body and forming umbrella-shaped cracks by utilizing high-pressure water jet in the drilling, specifically, the coal seam drilling pressure relief and the high-pressure water jet slotting are combined, a deep pressure relief area is created in the deep part of the drilling, differential pressure relief of different areas of the coal seam is realized, and the stability of roadway support and the elimination of rock burst danger are met. According to the deep slotting pressure relief and impact prevention method for rock burst coal seam drilling, coal seam drilling can be conducted to an impact dangerous area by using a small-diameter drilling machine, high-pressure water jet directional slotting is utilized to uniformly slotting on the circumferential surface of the drilling hole, umbrella-shaped pressure relief slots are formed, the purpose of expanding a pressure relief range is achieved, differential pressure relief in the pressure relief drilling hole is achieved, a shallow pressure relief range is small, roadway support stability is protected, a deep pressure relief range is large, and impact dangers are eliminated.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the application, and is not meant to limit the scope of the application, but to limit the application to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the application are intended to be included within the scope of the application.
Claims (8)
1. The deep slotting pressure relief and impact prevention method for rock burst coal seam drilling is characterized by comprising the following steps of:
determining a region range to be relieved;
Determining construction parameters of pressure relief drilling holes based on the range of the area to be relieved, and determining a slotting construction scheme based on the intensity of coal bodies in the impact dangerous area; in the slotting construction scheme, umbrella-shaped pressure relief slots are implemented in the pressure relief drilling holes to relieve pressure;
When in slotting construction, a plurality of groups of umbrella-shaped pressure relief slots are sequentially constructed from inside to outside in the pressure relief drilling holes by utilizing cutting equipment, each group of umbrella-shaped pressure relief slots comprises 8-12 symmetrical cracks, and the lengths of the cracks are controlled by controlling the cutting time in the implementation process;
when the occurrence of the coal seam in the area to be relieved is stable and no occurrence changes, the lengths of the plurality of cracks are the same;
when the area to be relieved is close to the fault structure, the crack length of one side close to the fault structure is longer than that of one side far away from the fault structure;
When the area to be relieved is close to the buckling structure, the length of the crack on the side close to the shaft part of the buckling structure is longer than that on the side far away from the shaft part of the buckling structure.
2. The method of deep slot pressure relief and scour protection for rock burst coal seam drilling of claim 1, further comprising, prior to determining the range of pressure relief to implement: and determining the pressure relief time based on the grade evaluation result of the impact dangerous area in the target area.
3. The method of deep slot pressure relief and scour prevention for rock burst coal seam drilling of claim 2, wherein the pressure relief engineering opportunity is determined according to the following conditions:
For a strong impact hazard zone, the pressure relief opportunity is: when the distance between the strong impact dangerous area and the working surface is not less than 300m, and the working surface is advanced for 60-70 days, the pressure relief engineering is started to be implemented;
for medium impact hazard zones, the pressure relief opportunities are: when the medium impact dangerous area is 200-300m away from the working surface, and the working surface is advanced for 50-60 days, the pressure relief engineering is started to be implemented;
For a weak impact hazard zone, the pressure relief opportunities are: and when the weak impact dangerous area is 100-200m away from the working surface, and the working surface is advanced for 30-40 days, the pressure relief engineering is started.
4. The method for deep slotting pressure relief and scour protection for rock burst coal seam drilling according to claim 1, wherein the step of determining the area range to be relieved is:
carrying out stress monitoring and drilling cuttings monitoring in a coal seam working face roadway with impact danger, obtaining a coal body supporting pressure distribution rule according to monitored data, drawing a supporting pressure curve, and determining the position of a supporting pressure peak value and the distance L between the peak value and the roadway side, wherein the range L to be relieved, in which pressure relief is required, is as follows:
Where l is the distance from the peak of the supporting pressure to the roadway side, and m.
5. The method of deep slot pressure relief and scour prevention for rock burst coal seam drilling of claim 1, wherein the construction parameters of the pressure relief drilling include depth, aperture and spacing of the pressure relief drilling; according to the grade evaluation result of the impact dangerous area, the distance D, the depth H and the aperture R of the pressure relief drilling holes are determined, and the method specifically comprises the following steps:
areas of high impact risk: r is less than or equal to D <1.5r, R is less than or equal to 42mm, and H=max (l+10, 20) m;
moderate impact hazard zone: d is less than or equal to 1.5r and less than or equal to 2.0r, R is less than or equal to 65mm, h=max (l+5, 15) m;
area of weak impact hazard: d <4.0r, r < 65mm, h=max (l, 15) m, 2.0 r;
Wherein R is the average length of the crack, D is the distance between the pressure relief drilling holes, H is the depth of the pressure relief drilling holes, and R is the aperture of the pressure relief drilling holes.
6. The method of deep slot pressure relief and scour protection for a rock burst coal seam borehole of claim 1, further comprising, prior to implementing the umbrella pressure relief slot in the pressure relief borehole: acquiring the coal body strength R c of the impact danger zone, and determining the diameter of a nozzle for performing slotting according to the following conditions based on the acquired coal body strength R c of the impact danger zone
When R c is less than or equal to 10MPa, phi is more than or equal to 3.0mm;
When R c is 10< 15MPa, phi is 2.0-3.0 mm;
When R c is more than or equal to 15MPa, phi is less than or equal to 2.0mm.
7. The deep slotting pressure relief and scour prevention method for rock burst coal seam drilling according to claim 1, wherein when the coal seam occurrence in the area to be relieved is stable and no occurrence changes, the cutting time of all cracks is T, and the cutting pressure is P;
If the fault fall is greater than the thickness of the coal seam, the cutting time is prolonged to T 1 and the cutting pressure is increased to P 1,T1＝1.3T-1.5T,P1 =1.2P-1.5P near one side of the fault;
If the fault fall is smaller than the thickness of the coal seam, the cutting time is prolonged to be T 3 and the cutting pressure is increased to be P 3,T3＝1.8-2T,P3 =1.8P-2P close to one side of the fault;
If the area to be relieved is close to one side of the anticline shaft part, the cutting time is prolonged to T 5, and the pressure is increased to P 5,T5＝1.5T,P5 =1.2P-1.5P;
If the area to be relieved is near one side of the syncline portion, the cutting time is prolonged to T 7 and the pressure is increased to P 7,T7＝2T,P7 =1.2p-1.5p.
8. The deep slotting pressure relief and impact prevention method for rock burst coal seam drilling according to claim 1, wherein the distance deltal between two adjacent umbrella-shaped pressure relief slots in the pressure relief drilling is determined according to the following formula:
Impact risk is evaluated as a region of strong impact risk: Δl is less than or equal to 1.0m;
impact risk was evaluated as a region of moderate impact risk: Δl is more than 1.0 and less than or equal to 2.0m;
impact risk was evaluated as a region of weak impact risk: Δl is more than 2.0 and less than or equal to 3.0m.
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| CN111608663A (en) * | 2020-04-29 | 2020-09-01 | 临沂矿业集团菏泽煤电有限公司 | Omnibearing pressure relief method for rock burst dangerous roadway of thick coal seam working face |
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| CN111608663A (en) * | 2020-04-29 | 2020-09-01 | 临沂矿业集团菏泽煤电有限公司 | Omnibearing pressure relief method for rock burst dangerous roadway of thick coal seam working face |
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