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 L 1 of the stress elevation zone, the length L 2 of the stress critical load zone, the length L 3 of the stress decline zone, and the length L 4 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 H 1, the height of the stress increase zone H 2 and the height of the stress superposition zone H 3 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.

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 L 1  of the stress elevation area, the length L 2  of the stress critical load area, the length L 3  of the stress decline area, and the length L 4  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 H 1 , the height of the stress augmentation zone H 2 , and the height of the stress superposition zone H 3 ;   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 S1˜S4, 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≤σ i ≤1.5 σ 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 1 ∈[L σc , L 1.5σc ]; when σ i ≥1.5 σ 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 2 =L ≥1.5σc ; 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 3 ∈[L 1.5σc , L σc ]. 
     
     
         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 4  is derived according to the evolution law of support stress distribution in the working face, L 4 =K 1  (L 1 +L 2 +L 3 ), K 1  is the work imbalance coefficient, and K 1  is taken as 1.2˜1.5. 
     
     
         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 i  and the value of the change of the chip volume is taken as ΔW. 
     
     
         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 ΔW∈[−0.2, 0.2] Kg/m 3 , it will be the height of the stress stabilisation zone H 1 ; when the change value of the chip-out quantity ΔW∈[0.2, 0.5] Kg/m 3 , it will be the height of the stress stabilisation zone H 2 ; and when ΔW≥0.5 Kg/m 3 , it will be the height of the height of stress superposition zone H 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 1  is 3 m, the spacing of the drill hole cuttings within the height of the coal body stress increase zone H 2  is 2 m, and the spacing of the drill hole cuttings within the height of the coal body stress superposition zone H 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 1 , 2) the heights of the stress height zone, H 2 , and 3) the heights of the stress superposition zone, H 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.