Decompression and Anti-Impact method by 3D Stratified Buffer Energy-Absorbing Belt for Thick coal seam

Abstract

The present invention relates to a technical solution of unloading pressure and shocking preventing, achieved by 3D stratified buffer and energy absorbing belt in thick coal seam. It is a technology for Prevention and Control of the Impact of Ground Pressure in Coal Mines that with Thick Coal Seam Bottom Roadway. Firstly, determine the distribution length L of the supporting stress curve along the advancing direction of the working face, divide the independent impact prevention unit by L, and sequentially determine the length L1 of the stress elevation zone, the length L2 of the stress critical load zone, the length L3 of the stress decline zone, and the length L4 of the stress static load zone, and also determine the different parameters of the spacing of the cutter drilling holes within the different stress zones; In the vertical direction of the working face, determine the height of the coal body stress stabilization zone H1, the height of the stress increase zone H2 and the height of the stress superposition zone H3 in turn, and determine the parameters of the cut slits and the location of the blocking grooves in different zones within the different stress zones. The appropriate jet parameters are adopted in different stress areas, and barrier slots are formed by continuous cutting at the junction of different partitions, which can both perform the function of coal unloading and block the stress transfer, solving the problems of insufficient and uneven unloading of coal seams.

Claims

1. A method for unloading pressure and preventing shocking impact in a three-dimensional stratified buffer energy-absorbing belt of a thick coal seam, characterized in that it comprises the following steps: S1 determining a length L of the distribution for the supporting stress curve along the advancing direction of the working face, dividing the coal body corresponding to L into an independent punching prevention unit, and partitioning the punching prevention unit along the advancing direction of the working face into the length L1 of the stress elevation area, the length L2 of the stress critical load area, the length L3 of the stress decline area, and the length L4 of the stress static load area, in that order; S2 Determine the arrangement spacing of slit drill holes in the direction of workface advancement and the arrangement spacing of stress prediction drill holes in different zones of an impact protection unit; S3 Construct the stress prediction drill holes, count the amount of drill chips from the stress prediction drill holes, deduce the stress distribution law in the vertical direction of the working face based on the amount of drill chips from the stress prediction drill holes, and divide the height of the stress stabilization zone H1, the height of the stress augmentation zone H2, and the height of the stress superposition zone H3; S4 According to the law of stress distribution in the vertical direction of the working face, determine the parameters of the cuts in the vertical direction of the working face and the location of the barrier grooves in different stress zones, and construct the cuts and barrier grooves; S5 Carry out the construction of impact protection and pressure relief for the remaining impact protection units according to steps S1S4, in order to form a three-dimensional pressure relief space in the whole coal seam.

2. A method of unloading pressure and preventing impact of a three-dimensional stratified buffer energy-absorbing belt in a thick coal seam according to claim 1, characterised in that: in step S1, when 0.sub.i1.5 .sub.c and there is an incremental increase in stress within the range from the front of the working face, it is determined that this interval is the length of the stress increase zone range L.sub.1[L.sub.c, L.sub.1.5c]; when .sub.i1.5 .sub.c within the range from the front of the working face, this interval is determined that this interval is the length of the stress critical load zone range L.sub.2=L.sub.1.5c; when the front face of the work and the stress is decreasing, the interval is determined as the length of the stress drop zone L.sub.3[L.sub.1.5c, L.sub.c].

3. A method of unloading pressure and preventing impact of three-dimensional stratified buffer energy-absorbing belt of thick coal seam according to claim 1, characterised in that: in step S1, the range of stress static loading area L.sub.4 is derived according to the evolution law of support stress distribution in the working face, L.sub.4=K.sub.1 (L.sub.1+L.sub.2+L.sub.3), K.sub.1 is the work imbalance coefficient, and K.sub.1 is taken as 1.21.5.

4. A method of unloading pressure and preventing impact of a three-dimensional stratified buffer energy-absorbing belt of thick coal seam according to claim 1, characterised in that: in step S2, a row of stress prediction boreholes is constructed at intervals of 30 m in the direction of advancement of back-mining face, and at least 3 boreholes are constructed in each row, controlling the two sides of the trench and the central position respectively.

5. A method of unloading pressure and preventing impact of a three-dimensional stratified buffer energy-absorbing belt in thick coal seam according to claim 1, characterised in that: in step S2, along the advancing direction of the working face, the spacing between the rows of cut-and-sew drilling holes within the range of stress-rising area and stress-decreasing area is 3 m; the spacing between the rows of cut-and-sew drilling holes within the range of stress-critical load area is 2 m; and the spacing between the rows of cut-and-sew drilling holes within the range of stress-quiet load area is 4 m.

6. A method for unloading pressure and preventing blowout of a three-dimensional stratified buffer energy-absorbing belt in a thick coal seam according to claim 1, characterised in that: in step S3, the average value of the chip volume of a unit penetration depth of a statistical stress prediction borehole is taken as W.sub.i and the value of the change of the chip volume is taken as W.

7. A thick coal seam three-dimensional stratified buffer energy-absorbing belt pressure unloading and anti-shocking impact method according to claim 6, characterised in that: in step S3, when the change value of the chip-out quantity W[0.2, 0.2] Kg/m.sup.3, it will be the height of the stress stabilisation zone H.sub.1; when the change value of the chip-out quantity W[0.2, 0.5] Kg/m.sup.3, it will be the height of the stress stabilisation zone H.sub.2; and when W0.5 Kg/m.sup.3, it will be the height of the height of stress superposition zone H.sub.3.

8. A method of unloading pressure and preventing impact of a three-dimensional stratified buffer energy-absorbing belt in a thick coal seam according to claim 1, characterised in that: in step S4, along the vertical direction of the working face, the spacing of the drill hole cuttings within the height of the coal body stress stabilisation zone H.sub.1 is 3 m, the spacing of the drill hole cuttings within the height of the coal body stress increase zone H.sub.2 is 2 m, and the spacing of the drill hole cuttings within the height of the coal body stress superposition zone H.sub.3 is 1 m.

9. A method of unloading pressure and preventing impact of a three-dimensional stratified buffer energy-absorbing belt in a thick coal seam according to claim 1, characterised in that: in step S4, the construction of supplemental slit drilling holes is carried out, and coherent blocking grooves are cut at: 1) the heights of the stress stability zone of the coal body, H.sub.1, 2) the heights of the stress height zone, H.sub.2, and 3) the heights of the stress superposition zone, H.sub.3, respectively.

10. A method of unloading pressure and preventing impact in a thick coal seam with three-dimensional stratified buffer energy-absorbing belt according to claim 1, characterised in that: water jetting anti-impact pressure-unloading construction is carried out on the anti-impact unit in the bottom lane of the coal seam.

Description

[0027] Attachment labels: coal seam 1, backing face 1-1, coal seam unloading area 1-2, coal seam floor 3, bottom drawdown lane 4, working face support stress curve 5, cuttings borehole 6, stress prediction borehole 7, length of stress elevation zone L1, length of stress critical loading zone L2, length of stress drop zone L3, length of stress static loading zone L4, roadway stress curve 8, superimposed stress curve of the working face 9, cuttings slot 10, blocking slots 11, Supplementary slit drilling 12, Stress stabilisation zone height H1, Stress increase zone height H2, Stress superposition zone height H3.

IMPLEMENTATION

[0028] The following illustrates the embodiments of the present invention by means of particular specific examples, and other advantages and efficacies of the present invention can be readily understood by those skilled in the art from the contents disclosed in this specification. The present invention may also be implemented or applied in different specific embodiments, and the details in this specification may be modified or changed in various ways based on different views and applications without departing from the spirit of the present invention. It is to be noted that the illustrations provided in the following embodiments illustrate the basic concept of the present invention in a schematic manner only, and the following embodiments and the features in the embodiments may be combined with each other without conflict.

[0029] Among them, the accompanying drawings are for exemplary illustration only, and represent only schematic drawings, not physical drawings, and cannot be understood as a limitation of the present invention; in order to better illustrate the embodiments of the present invention, certain parts of the accompanying drawings will be omitted, enlarged, or reduced, and do not represent the dimensions of the actual product; it is understandable to the person skilled in the art that certain well-known structures and their descriptions in the accompanying drawings may be omitted.

[0030] In the accompanying drawings of the embodiments of the present invention, the same or similar symbols correspond to the same or similar parts; in the description of the present invention, it is to be understood that the terms up, down, left, right, front, back and the like indicate orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings only for the purpose of illustration. up, down, left, right, front, back and the like indicate orientation or positional relationships based on those shown in the accompanying drawings, and are used only for the purpose of facilitating the description of the present invention and simplifying the description. The description of the present invention and the simplification of the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, therefore the terms describing the positional relationships in the accompanying drawings are only used for exemplary illustration and are not to be construed as a limitation of the present invention, and the specific meanings of the above terms may be understood by a person of ordinary skill in the field in accordance with the specific circumstances.

[0031] Referring to FIGS. 1-3, a three-dimensional layered buffer energy-absorbing belt pressure-unloading and anti-impact method for thick coal seams is based on the stress distribution law in the advancing direction and the vertical direction of the back-mining face of thick coal seams, and water jet pressure-unloading drilling is carried out in the bottom lane of the coal seams in the stress-concentrated area of the back-mining area, and the buffer energy-absorbing belt is formed by cutting the barrier grooves inside the coal seams. Firstly, the distribution length L of the supporting stress curve is estimated along the advancing direction of the working face, and an independent anti-shock unit is divided. Determine the length of the stress increase zone L1, the length of the stress critical load zone L2, the length of the stress decrease zone L3, and the length of the stress static load zone L4, and determine different spacing parameters of the cutter drill holes in different stress zones. In the working vertical direction, determine the height of coal body stress stabilisation zone H1, the height of stress increase zone H2, the height of stress superposition zone H3, and determine the parameters of the slit and the location of the blocking groove in different stress zones. Reasonable jet parameters are adopted in different stress areas, and barrier slots are formed by continuous cutting at the junction of different partitions, which not only play the role of coal unloading, but also block the stress transfer, solve the problems of insufficient and uneven unloading of coal seams, and form the three-dimensional unloading of thick seams, which effectively reduces the risk of impact pressure in coal seams.

[0032] This includes the following steps: [0033] S1 According to the basic geological data such as the coal seams' storage conditions, parameters of coal body mechanics, working face layout, etc., estimate the length of the supporting stress curve distribution along the advancing direction of the working face, L. Determine the length of the stress increase zone, L1, the length of the stress critical load zone, L2, the length of the stress decrease zone, L3, and the length of the stress static load zone, L4, in that order.

[0034] S2 According to the supporting stress distribution law in the advancing direction of the back-mining face, determine the spacing of the arrangement of slit drill holes 6 and stress prediction drill holes 7 in different subdivisions of a three-dimensional independent unit for the prevention and control of ground pressure impact.

[0035] S3 Stress prediction drilling adopts the statistical method of drilling chip volume to deduce the stress distribution pattern in the vertical direction of the working face, and reasonably classify the height of the stress increase zone H2 and the height of the stress superposition zone H3.

[0036] S4 According to the law of stress distribution in vertical direction of thick coal seam mining back in the face, determine the parameters of the cut seam and the location of the blocking groove in different stress zones.

[0037] S5 With reference to the construction parameters determined in steps S1S4, carry out the construction of the anti-impact pressure unloading works on the remaining anti-impact units to form a three-dimensional pressure unloading space in the entire coal seam.

[0038] Preferably, the length L of the distribution field of the support stress curve of the working face is determined by the law of distribution of the support stress in front of the 1-1 front of the return mining face, i.e. L=L1+L2+L L3+4. The coal body within the length L of the distribution of the support stress curve of the working face in front of the working face of the thick seam is treated as a three-dimensionally independent unit of the prevention and control of the impact ground pressure.

[0039] Preferably, based on the theory of Rock Control, the strength of the coal body c is calculated based on the burial depth of the coal seam, which can be measured and calculated by means of CT stress scanning, stress gauges, numerical simulation analyses and other means of calculating the working face support stress i at Li in front of the 1-1 front of the return mining face.

[0040] Preferably, when 0i1.5 c and there is an increasing stress in the range from the front of the workpiece, the interval is determined to be a stress elevation zone length range L1[Lc, L1.5c].

[0041] Preferably, the interval is determined to be the stress critical load zone length range L2=L1.5c when i1.5c from the front of the working face range.

[0042] Preferably, the interval is determined to be a stress drop zone length range L3[L1.5c, Lc] when 1.5cic and there is a decreasing stress condition from the front side of the work.

[0043] Preferably, when i=c in the range from the front of the working face, it can be determined that this interval is the range of the stress static load zone L4. Based on the evolution law of the work face support stress distribution, L4=K1 (L1+L2+L3), K1 is the work imbalance coefficient, and K1 is generally taken to be 1.21.5.

[0044] Preferably, the purpose of constructing the stress prediction drill holes is to obtain the stress distribution law in the vertical direction of the working face, and to provide a basis for determining the parameters of the spacing of the cuttings for the cuttings drill holes 6. A row of stress prediction drill holes is constructed at intervals of 30 m from the advancing direction of the return mining face, and each row of drill holes is at least 3, respectively controlling the working two sides of the trough and the central position.

[0045] Preferably, the slit boreholes 6 are spaced at different parameters within different stress zones. The spacing of the slit drilling holes 6 is 3 m within the stress rise and stress fall zones, 2 m within the stress critical load zone, and 4 m within the stress static load zone.

[0046] Preferably, the chip-out per unit depth of coal penetration from the coal sighting point to the final hole point is counted for each of the stress prediction drill holes 7 W1i, W2i, W3i, i being the unit depth of coal penetration. The chip output per unit depth of coal penetration for the three stress prediction drill holes 7 is averaged Wi=(W1i+W2i+W3i)/3.

[0047] Preferably, the value of the change in the amount of chips per unit depth of the coal seam W=Wi+1Wi. When W[0.2, 0.2] Kg/m3, reflecting a more uniform distribution of stresses within the scope of the region of the depth of penetration of the coal can be determined as the height of the stress stabilisation zone H1.

[0048] Preferably, the value of the change in chip output per unit depth of the coal seam W=Wi+1Wi. When W[0.2, 0.5] Kg/m3, the chip output within the range of this penetration depth region gradually increases, reflecting the gradual increase in the stress of the coal body, and the height of the stress stabilisation zone H2 can be determined.

[0049] Preferably, the change value of chip-out per unit depth of the coal seam is calculated as W=Wi+1Wi. When W0.5 Kg/m3, the chip-out within the range of this penetration depth region is obviously increased, reflecting that the interior of the coal body has been extruded due to the high stress, and the height of the stress superimposed zone can be determined H3

[0050] Preferably, the drilling cuttings are spaced vertically 3 m apart within the height H1 of the coal body stress stabilisation zone, 2 m apart vertically within the height H2 of the coal body stress augmentation zone, and 1 m apart vertically within the height H3 of the coal body stress superposition zone.

[0051] When the barrier slots 11 cannot be made to pass through by the slit drilling holes 6, coherent barrier slots 11 can be cut by constructing supplementary slit drilling holes 12 at the heights of the stress stabilisation zone of the coal body H1, the height of the stress stabilisation zone of the coal body H2, and the height of the stress superposition zone of the coal body H3, respectively, so as to form a cushioning and absorbing zone between the barrier slots 11.

Example of Implementation

[0052] This embodiment takes the coal second layer of an impact ground pressure mine as a geological background, which has the danger of protruding and impacting compound power disaster. The back-mining face is located in the southern part of the sixth mining area of the second seam of coal, with the ground elevation between 1995 and 2320 m, and the burial depth between 594 and 777 m, and the mined coal seam is the second seam of coal, with the thickness of 25.04-45.0 m and the average of 34.5 m, and the mining height of the working face is 5 m, and the inclination angle of the coal seam is 5-15, and the working face is designed to have the strike length of 584 m, the inclination width of 120 m, and the strength of the coal body is c=18 MPa.

[0053] A method of unloading pressure and preventing impact in a thick coal seam with three-dimensional stratified buffer and energy absorbing belt, referring to FIGS. 1 to 3, which show a coal seam 1, a backing face 1-1, a coal seam unloading area 1-2, a coal seam footing 3, a bottom drawdown lane 4, a working face support stress curve 5, a cuttings drilling hole 6, a stress prediction drilling hole 7, a length of a stress elevation zone L1, a length of a stress critical loading zone L2, a length of a stress decrease zone L3, a length of a stress static loading zone L4, Tunnel stress curve 8, working face superimposed stress curve 9, slit groove 10, barrier groove 11, supplementary slit borehole 12, stress stabilisation zone height H1, stress increase zone height H2, stress superimposed zone height H3, comprising the steps of:

[0054] S1 According to the basic geological data, such as the conditions of the coal seam, the characteristic parameters of coal body mechanics, and the layout of the working face, the CT stress scanning method was used to study the stress distribution law along the advancing direction of the working face. In the range of 025 m in front of the working face, the coal body stress is 027 MPa with an increasing trend, in the range of 2540 m, the stress 0 is more than 27 MPa, and the maximum value is 40 MPa, which shows the trend of increasing and then decreasing, in the range of 4070 m, the stress is 1827 MPa, and the stress is about 18 MPa after the range of 70 m.

[0055] According to the above stress distribution range, it can be seen that the stress in front of the working face shows the state of increasing and then decreasing and tends to moderate, and the composite working face support stress distribution law. According to the division of stress rise area (0i1.50c), stress critical load area (i1.50c), stress drop area (1.5cic), it can be determined that the length of the stress rise area is 35 m, the length of the stress critical load area is 40 m, and the length of the stress drop area is 70 m in turn.

[0056] According to the working face supporting stress distribution evolution law, L4=K1 (L1+L+L23), K1 is the work imbalance coefficient, K1 take 1.5, can calculate the length of the stress static load zone L4=1.5(25+15+30)=105 m; Determine the length of the distribution field of the supporting stress curve of the working face, i.e., L=L1+L2+L3+L4=25+15+30+105=175 m; Therefore, the coal seam within the range of 175 m in front of the working face can be treated as a three-dimensional independent unit; the three-dimensional independent unit to prevent impact ground pressure is divided by the length of working face according to the management of a separate unit. Therefore, the coal seam within the range of 175 m in front of the working face can be regarded as a three-dimensional independent unit for preventing and controlling impact ground pressure; the three-dimensional independent unit for preventing and controlling impact ground pressure is divided by the length of the working face, and those that don't satisfy the length of an independent unit are managed according to a separate unit. Therefore, the length of working face 1 is 584 m, n=[1/L]+1=[584175]+1=4, so the working face can be divided into 4 units.

[0057] S2 According to the supporting stress distribution law in the advancing direction of the back-mining face, the spacing of the arrangement of slit drill holes 6 and stress prediction drill holes 7 is determined in different partitions of a three-dimensional independent unit for the prevention and control of impact ground pressure, and the rest of the impact prevention units are managed according to the same approach.

[0058] The purpose of constructing the stress prediction drill holes is to obtain the stress distribution law in the vertical direction of the working face, and to provide a basis for determining the spacing parameters of the slit drill holes. A row of stress prediction drill holes is constructed at intervals of 30 m from the advancing direction of the back-mining face, and each row of drill holes is at least 3 holes, respectively controlling the working two sides of the trench and the central position, so 6 rows of stress prediction drill holes need to be arranged in an independent anti-impact unit.

[0059] In different stress zones, the slit borehole 6 adopts different spacing parameters. The spacing between the rows of slit drill holes 6 in the stress rise zone and stress fall zone is 3 m, the spacing between the rows of slit drill holes 6 in the stress critical load zone is 2 m, and the spacing between the rows of slit drill holes 6 in the stress static load zone is 4 m. Therefore, a total of 8 rows of slit drill holes 6 are arranged in the stress rise zone, a total of 7 rows of slit drill holes 6 are arranged in the stress critical load zone, a total of 10 rows of slit drill holes 6 are arranged in the stress fall zone, and a total of 21 rows of slit drill holes 6 are arranged in the stress fall zone.

[0060] S3: Stress prediction drilling adopts the statistical method of drilling chip volume to deduce the stress distribution law in vertical direction of the working face, and reasonably classify the height of the stress increase area H2 and the height of the stress superposition area H3.

[0061] The debris output per unit depth of coal penetration from the coal sighting point to the final point of each stress prediction drill hole 7 was counted W1i, W2i, W3i, i being the unit depth of coal penetration. The average value of chip output per unit depth of coal penetration for the three stress prediction drill holes 7 is Wi=(W1i+W2i+W3i)/3.

[0062] Calculate the change value of chip volume per unit depth of the seam W=Wi+1Wi. Calculate the change value of chip volume W by counting the chip volume per unit depth of coal penetration Wi. In the range of 5 m height of the coal seam at the point of seeing the coal, W[0.2, 0.2] Kg/m3. In the range of 525 m height, W[0.2, 0.5] Kg/m3 and the chip volume of the drilled holes increases gradually. In the height range from 25 to 40 m, W0.5 Kg/m3.

[0063] Determine the height of the working face H1 which is 5 m, the height of the stress increase zone H2 is 20 m, and the height of the stress superposition zone H3 is 15 m.

[0064] S4 According to the law of stress distribution in the vertical direction of thick coal seam mining back in the face, construct different parameters of cuttings and locations of blocking grooves in different stress zones.

[0065] The spacing of drill cuttings is 3 m within the height of the coal body stress stabilisation zone H1=5 m, 2 m within the height of the coal body stress increase zone H2=20 m, and 1 m within the height of the coal body stress superposition zone H3=15 m.

[0066] By constructing supplementary cuttings drilling 12, the blocking slots 11 were constructed at locations 5 m, 25 m and 40 m respectively from the height of the coal seam floor.

[0067] S5 With reference to the construction parameters determined in steps S1S4, the remaining anti-punching units carry out anti-impact and pressure relief works to form a three-dimensional pressure relief space in the entire coal seam.

[0068] The present invention forms three-dimensional pressure unloading and anti-impact of thick coal seam by unloading pressure in layers and managing in zones inside the thick coal seam, effectively reduces the danger of ground pressure impact of coal seam, and solves the problems of insufficient and uneven pressure unloading of thick coal seam in the ground pressure impact mines.

[0069] Finally, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to be limiting, although the present invention has been described in detail with reference to the preferred embodiments, the person of ordinary skill in the art should understand that modifications or equivalent replacements can be made to the technical solutions of the present invention without departing from the purpose and scope of the present technical solutions, which should be covered by the scope of the claims of the present invention.