Collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting

Patent metadata

Field	Value
Publication number	US-11834949-B2
Application number	US-202318178385-A
Country	US
Kind code	B2
Filing date	Mar 3, 2023
Priority date	Apr 22, 2022
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

A collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting provided by the disclosure includes the following steps: step 1 , driving into a coal seam to release pressure; step 2 , low roof pre-splitting during driving process; step 3 , supporting of roadway surrounding rock and support reinforcement; step 4 , floor destressing of the roadway; step 5 , high roof pre-splitting before mining; step 6 , destressing and supporting of the advanced roadway surrounding rock during the mining process of the working face. The collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting, and to carry out local pressure relief, roof pre-splitting and reinforcement support construction in the whole cycle of the coal working face in a progressive manner, so as to achieve the prevention and control of rock burst in the working face.

First claim

What is claimed is:

1. A collaborative erosion-control method of releasing-splitting-supporting based on coal mass pressure relief and roof pre-splitting, comprising the following steps:
step 1 , driving into a coal seam to release pressure;
step 11 , constructing 1-3 pressure relief holes in a roadway of a driving face according to a rock burst hazard level of a working face with each round of driving construction during a cyclic driving construction of a roadway of the working face, wherein the pressure relief holes are 0.5-1.5 m from a floor, a diameter of the pressure relief holes is 100-300 mm, and a depth of which is a sum of a driving planned drilling depth and a distance between a peak value of bearing pressure of the driving face and a coal wall; the pressure relief holes are constructed in a side of roadway within 20 m behind the driving face, a distance between the adjacent pressure relief holes is 1-3 m, the diameter of the pressure relief holes is 100-300 mm, a depth of the pressure relief holes is 15-45 m, and a height of the pressure relief holes from the floor is 1.0-1.5 m;
wherein, in a region with weak rock burst hazard level, one pressure relief hole is constructed in the driving face; in a region with medium and strong rock burst hazard level, 2-3 pressure relief holes are constructed in the driving face;
a comprehensive index method is used to determine the rock burst hazard level; if the rock burst hazard index is less than 0.25, it is defined as no rock burst hazard; if the rock burst hazard index is greater than or equal to 0.25 and less than 0.5, it is defined as the weak rock burst hazard level; if the rock burst hazard index is greater than or equal to 0.5 and less than or equal to 0.75, it is defined as the medium rock burst hazard level; if the rock burst hazard index is greater than 0.75, it is defined as the strong rock burst hazard level;
step 12 , carrying out a sectional destress drilling in a roadway section in a region with strong rock burst hazard level, a roadway section with the side of the roadway of a displacement of 10-20 mm or a roadway section with reduced anchor bolt support strength, wherein the distance of the pressure relief holes is 1-3 m, the depth of the pressure relief holes is 15-45 m, a diameter of the pressure relief holes in the 0-5 m section is 70-100 mm, and a diameter of the pressure relief holes in a 5-45 m section is 150-300 mm;
step 13 , constructing a grouting anchor bolt between two adjacent pressure relief holes on the side of the roadway before a next round of construction, wherein the grouting anchor bolt is provided with a stress meter, and the stress meter is configured to monitor stress of the grouting anchor bolt in real time; replacing the grouting anchor bolt when the stress of the grouting anchor bolt decreases to 80%;
step 14 , carrying out a drill cuttings monitoring to obtain a drilling powder rate index on two sides of a pressure relief hole of two sides of a roadway of a coal mass to determine a pressure-relief effect; if the drilling powder rate index is greater than 1.5, it still has a risk of rock burst, then densifying the pressure relief hole to release pressure on the two sides of the roadway of the coal mass again until the drilling powder rate index is less than 1.5, wherein drill holes in the two sides of the roadway are perpendicular to an axial direction of the roadway when densifying the pressure relief hole; a diameter of the drill holes is 42-100 mm, a distance between the drill holes is 5-20 m, and a depth of the drill holes is the distance from a peak point of stress concentration zone to the coal wall;
step 2 , low roof pre-splitting during driving process;
step 21 , carrying the drill cuttings monitoring on within 100 m from the driving face in the driving process of the roadway, wherein a depth of drill holes of the drill cuttings monitoring is not less than 15 m, and a distance between the drill holes is 10-25 m; drawing an equivalent stress contour map and an equivalent stress distribution pattern map according to an amount of pulverized coal corresponding to different drilling depths;
step 22 , selecting step a or step b to carry out roof pre-splitting construction;
step a, blasting pre-splitting;
step a 1 , determining a position of charge section of the roof pre-splitting;
recording that a distance between a equivalent stress peak of the two sides of the roadway in far distance and the coal wall is p x meters, drawing a peak stress line of the two sides of the roadway on a equivalent stress contour map in step 21 , and recording a range of stress peak region of 0.95 p x -p x meters from the coal wall as a, that is, a stress stability region; recording a range 1.0-1.3 m from the peak stress line of the two sides of the roadway as b; an intersection range obtained from a and b is a projection of the charge section of the roof pre-splitting on a horizontal plane, so as to determine the position of the charge section of the roof pre-splitting;
step a 2 , determining an angle of blast holes and a position of a target rock layer of a pre-splitting roof;
determining an elevation angle of the blast holes according to a vertical distance h from a bottom of a hole of the charge section to the coal seam and a horizontal distance 1 from the side of the roadway;
then calculating the elevation angle of blasting drillhole by the formula:
θ=arctan( h/l );

in the formula,
in consideration of an influence of dynamic load generated by roof blasting on a stability of the coal mass in the side of the roadway, h is taken as 5-7 m;
l =( p x −1.3);

step a 3 , arranging of the blast holes;
constructing the blast holes from shoulder angle positions of the two sides of the roadway to the roof at a roadway location where the stress stability region is located, wherein a distance of the blast holes is 5-20 m, and a charge quantity of the blast holes achieves an effect of loosening rock mass without causing a collapse of the rock mass;
step a 4 , detonating explosive charges in the blasting drillhole;
step b, hydraulic pre-splitting;
determining a position with a highest amount of the pulverized coal as a bearing pressure peak position of the sides of the roadway according to the equivalent stress distribution pattern map in step 21 , and constructing hydraulic drillholes from the shoulder angle positions of the two sides of the roadway to the roof;
wherein, a horizontal distance of the hydraulic drillholes exceeds 1-2 m over the bearing pressure peak position of the sides of the roadway, recorded as l r ; a vertical distance from the hydraulic drillholes to the coal seam is 3-5 m, recorded as h r ; then a dip angle of the hydraulic drillholes is: θ=arctan(h r /l r );
water injection equipment is connected with the hydraulic drillholes through a water injection pipeline;
injecting water, by the water injection equipment, into the hydraulic drillholes; when water seeps out of the roadway roof or the side of the roadway, or when water seeps out during the hydraulic drillholes, the hydraulic pre-splitting is completed;
step 3 , supporting of roadway surrounding rock and support reinforcement;
step 31 , using anchor bolts, anchor bolt cables, ladder beams and steel bands for support when the roadway is driven to a section roof and the two sides of the roadway during the driving process; wherein a length of the anchor bolts is 1.8-2.4 m, a distance between the anchor bolts is 800-1200 mm, and a row spacing of the anchor bolts is 800-1200 mm; the anchor bolt cable is installed immediately following a construction of the driving face, with a distance of 800-1200 mm and a row spacing of 800-1200 mm; a beam spacing between the ladder beams is 2000 mm; a length of steel beam is 4000 mm, and a band spacing is 2000 mm;
step 32 , conducting a real-time monitoring to a roadway displacement

Assignees

• Univ Shandong Science & Tech

Inventors

• Guo Weiyao
• Chen Lexin
• Tan Yan
• Tan Yunliang
• Zhao Tongbin

Classifications

• E21C41/18 Primary

  for brown or hard coal · CPC title

• E21D20/00

  Setting anchoring-bolts (anchoring bolts for shafts, tunnels or galleries E21D21/00; means for anchoring structural elements or bulkheads specially adapted to foundation engineering E02D5/74; dowels or other devices fastened in walls or the like by inserting them in holes made therein for that purpose F16B13/00) · CPC title

• E21D21/02 Primary

  having means for indicating tension (screwed connections specially modified for indicating tensile load F16B31/02) · CPC title