WO2016150188A1

WO2016150188A1 - Method for fracturing filler wall left behind in adjacent coal-mining face

Info

Publication number: WO2016150188A1
Application number: PCT/CN2015/095914
Authority: WO
Inventors: 张农; 潘东江; 吕创新; 韩昌良; 薛飞
Original assignee: 中国矿业大学
Priority date: 2015-03-25
Filing date: 2015-11-30
Publication date: 2016-09-29
Also published as: ZA201701756B; CN104847406B; AU2015387618A1; AU2015387618B2; CN104847406A

Abstract

A method for fracturing a filler wall left behind in an adjacent coal-mining face, applicable in continuous pressure-relief mining of a coal seam group at a great depth. A drill hole (2) distribution scheme, parameters, and a volume of an explosive charge are designed on the basis of the size of a filler wall (1), a construction scheme for same, and a state of earlier damages of same; one to three rows of downward tilted drill holes are constructed by an advancing coal-mining face (3) on a filler wall left behind and reused by an adjacent coal-mining face (4) in a tunnel; one to two rows of the drill holes in the rear within an extremity hydraulic frame (6) are filled with the explosive charge and sealed; as the coal-mining face advances, the drill holes filled with the explosive charge in the rear within the extremity hydraulic frame enter the rear side of the coal-mining face, microcracks on the filler wall caused by earlier mining pressure are utilized to intensify cracking of the filler wall, and, combined with the effect of a lagging mining-induced stress, the filler wall left behind is ultimately fractured. The method allows fracturing of the filler wall left behind in a goaf by the adjacent coal-mining face, thus effectively eliminating an effect of stress concentration posed by the filler wall to upper and lower adjacent coal seams, implementing the goal of continuous pressure relief, and solving safety risks of adjacent coal seam mining.

Description

Method for cracking residual filling wall of adjacent coal mining face

Technical field

The invention relates to a method for cracking a residual filling wall of an adjacent coal mining face, and is particularly suitable for continuous pressure relief mining of a deep coal seam group.

Background technique

The retaining lane along the empty space is to construct a wall with a certain bearing capacity along the edge of the goaf, and retain the mining roadway of the adjacent coal mining face as the mining face of the coal mining face. It is one of the key technologies for continuous pressure relief mining of deep coal seams. It is used to solve the safety problems of rock burst, coal and gas outburst, high gas and high ground pressure.

At present, it is more and more common to use cement-based materials to construct walls along the empty roadway, especially in deep mining areas. The cement-based wall is fast-setting and early-strength, supplemented by reinforcing bolts and three-dimensional reinforced ribs, which can basically ensure the normal use of the mining roadway of the two coal mining faces. Although the cement-based wall is affected by the two mining forces, it still increases the resistance and can not self-destruct the bearing capacity. The concentrated stress zone is formed in the upper and lower adjacent coal seams, which can not achieve the purpose of continuous pressure relief. It is a safety hazard adjacent to coal seam mining. Therefore, there is an urgent need to provide a method to aggravate the filling wall of the adjacent coal mining face left in the goaf when the mining face is recovered, and destroy its bearing capacity.

Summary of the invention

Technical Problem: The object of the present invention is to overcome the deficiencies in the prior art and to provide a method for cracking a residual filling wall of an adjacent coal mining face.

Technical Solution: The method for leaving the wall of the adjacent coal mining face of the present invention is as follows:

a. According to the size of the filling wall, the construction method and the damage state in the early stage, design the drilling arrangement, parameters and charge amount;

b. Advance coal mining face, in the lane to the adjacent coal mining face to retain the reuse of the filling wall construction 1 to 3 rows of inclined downward drilling;

c. Coal mining and charging operations are carried out simultaneously, the charging step is not greater than the stepping distance of the end hydraulic support, and 1 to 2 rows of drilling and grouting charges are arranged inside the end of the hydraulic support frame; the grouting slurry Made of SCA-I or SCA-II type static breaker, the hole is sealed with yellow mud or polyurethane foam;

d. With the advancement of the coal mining face, the drilled hole in the inner end of the end hydraulic support frame enters the rear of the coal mining face, and the expansion pressure is generated after 3 to 8 hours, and the micro-cracks initiated by the mining pressure in the early stage of the filling wall are used. Intensifying the cracking of the filling wall, combined with the influence of the delayed mining stress, and the remaining filling wall is finally broken;

e. Repeat steps b and c until the completion of the cracking of the adjacent coal mining face leaving the filling wall.

The inclined downward drilling hole has an inclination angle of 10 to 25°, a hole diameter of 40 to 100 mm, a hole pitch of 0.4 to 0.8 m, a row spacing of 0.3 to 0.7 m, a hole pitch of the top and a bottom plate of 0.5 to 1.0 m, and a bottom of the hole. The side of the gob from the filling wall is 20 to 30 cm.

The water agent ratio of the grouting slurry is 0.25 to 0.35, and the charge amount of the static crushing agent per unit volume of the filling wall is 10 to 25 kg.

Advantageous Effects: Compared with the prior art, the present invention has the advantages of good effect, low cost, simple operation, safety and reliability. The specific advantages are as follows:

1) The static crushing agent has a large expansion force, and the micro-cracks initiated by the mining pressure in the early stage of the filling wall are used to aggravate the filling wall left in the goaf by the adjacent coal mining face, and combined with the effect of the lag mining stress. The resulting wall is finally broken. The overburden can fully sink, effectively eliminating the stress concentration effect of the wall on the upper and lower adjacent coal seams, achieving the purpose of continuous pressure relief, and solving the safety hazard of adjacent coal seam mining.

2) In the static crushing process, no flying stones, dust, and exhaust gas are generated, and the safety factor is high.

3) The pre-drilling hole is inclined by 10~25°, which is convenient for workers to work, and partially utilizes the characteristics that the wall body is prone to brittle tensile damage along the 45° oblique section, which effectively saves the crushing power and reduces the crushing cost.

4) The worker is working ahead of the coal mining face or the end hydraulic support frame for safe operation.

5) The process is simple and convenient to operate, the worker has low work intensity and less work time.

DRAWINGS

1 is a schematic plan view of the coal mining face of the present invention when it is recovered;

Figure 2 is a schematic view showing the arrangement of drilling holes near the end hydraulic support of the present invention;

Figure 3 is a schematic cross-sectional view of a wall of the present invention.

In the figure: 1-fill wall; 2-hole; 3- coal face; 4- adjacent coal face; 5-static breaker; 6-end hydraulic support; 7-yellow mud or polyurethane foam.

detailed description

An embodiment of the present invention will be further described below with reference to the accompanying drawings:

The method for cracking the adjacent coal mining face leaving the wall in the present invention, the specific steps are as follows:

a. According to the size, construction mode and pre-destruction state of the filling wall 1, design the layout, parameters and loading amount of the drilling hole 2;

b. Advance coal mining face 3, in the lane to the adjacent coal mining face 4, the multiplexed filling wall 1 is reserved for construction 1 to 3 rows of inclined downward drilling 2; the inclined downward drilling 2 is inclined The angle is 10~25°, the aperture is 40-100mm, the pitch is 0.4-0.8m, the row spacing is 0.3-0.7m, the hole is 0.5~1.0m from the top and the bottom plate, and the hole bottom is filled with the gob of the wall 1. The side is 20 to 30 cm.

c. Coal mining and charging operations are carried out simultaneously, the charging step is not greater than the stepping distance of the end hydraulic support 6, and the first to second rows of bores 2 of the end of the hydraulic support 6 are filled with grouting charge; The grouting slurry is prepared by mixing water with SCA-I or SCA-II type static breaking agent 5, and the drilling hole is sealed with yellow mud or polyurethane foam 7; the ratio of water to the grouting slurry is 0.25-0.35 The filling amount of the static crushing agent 5 per unit volume of the filling wall 1 is 10 to 25 kg.

d. With the advancement of the coal mining face 3, the borehole 2, which has been filled in the rear of the 6-end hydraulic support, enters the rear of the coal mining face 3, and after 3 to 8 hours, the expansion pressure is generated, and the front wall of the filling wall 1 is utilized. The micro-cracks generated by the pressure increase the cracking of the filling wall (1), combined with the influence of the lag mining stress, and the remaining filling wall 1 is finally broken;

Embodiment 1. A filling wall of a mine adjacent to the coal mining face 4 is multiplexed with a width × height = 3 m × 2.6 m, and is constructed by pumping C30 paste material and supplemented with a shear anchor. When the coal mining face is recovered, the stress concentration peak appears at the leading working face of 13m, and the stress concentration factor reaches 1.67. Here, the overall quality of the filling wall 1 is good, and a small amount of cracks appear on the surface.

The coal face of the advanced coal face is 3m away from the surface of the

filling wall

1 and 2 rows of inclined downward boreholes 2, the inclination angle is 15°, the aperture is 50mm, the hole spacing is 0.6m, the row spacing is 0.6m, and the hole is 1.0m from the top plate. 1.0m from the bottom plate, the bottom of the hole is 25cm away from the other side of the wall 1.

Coal mining and charging operations are carried out simultaneously. According to the principle that the charging step is not more than the stepping distance of the end hydraulic support 6, the stepping distance of the end hydraulic support 6 is 0.6 m, and it is determined that one row of the bore grouting charge is arranged inside the rear end of the hydraulic bracket 6 of the end. SCA-II type static breaking agent 5 is used, the water agent ratio is about 0.3, and the orifice is about 10 cm, and the yellow mud 7 is used for sealing. The volume of the static crushing agent 5 per unit volume of the filling wall 1 is 10 to 25 kg.

With the advancement of the coal mining face 3, the already-filled borehole 2 enters the rear of the coal mining face 3, and after 3 to 8 hours, the expansion pressure is generated, and the micro-cracks initiated by the pre-mineral pressure of the filling wall 1 are used to intensify the filling wall. 1 cracking. Combined with the influence of the lag mining stress, the remaining filling wall 1 is finally broken.

As shown in Figure 1, Figure 2, Figure 3.

Claims

A method for cracking a residual filling wall of an adjacent coal mining face, characterized in that the method comprises the following steps:

a. According to the size of the filling wall (1), the construction method and the damage state in the early stage, design the drilling (2) layout, parameters and charge;

b, ahead of the coal mining face (3), in the lane to the adjacent coal mining face (4) to retain the multiplexed filling wall (1) construction 1 ~ 3 rows of inclined downward drilling (2);

c. Coal mining and charging operations are carried out simultaneously. The charging step is not greater than the stepping distance of the end hydraulic support (6), and the drilling of the inner and rear columns of the end hydraulic support (6) is 2 to 2 rows (2) Grouting charge; the grouting slurry is prepared by mixing water with SCA-I or SCA-II type static breaking agent (5), and the drilling hole is sealed with yellow mud or polyurethane foam (7);

d. With the advancement of the coal mining face (3), the drilled hole (2) inside the end of the end hydraulic support (6) enters the coal mining face (3), and the expansion pressure occurs after 3-8 hours. The micro-cracks initiated by the pre-mineral pressure of the filling wall (1) are used to intensify the cracking of the filling wall (1), combined with the influence of the delayed mining stress, and the remaining filling wall (1) is finally broken;

e. Repeat steps b and c until the completion of the cracking of the adjacent coal mining face leaving the filling wall.
The method according to claim 1, wherein the inclined downward drilling hole (2) has an inclination angle of 10 to 25° and a hole diameter of 40 to 100 mm. The hole spacing is 0.4-0.8m, the row spacing is 0.3-0.7m, the hole is 0.5~1.0m from the top and the bottom plate, and the bottom of the hole is 20~30cm away from the side of the gob of the filling wall (1).
The method according to claim 1, wherein the grouting slurry has a water agent ratio of 0.25 to 0.35, and the unit volume filling wall (1) is statically broken. The charge of the agent (5) is 10 to 25 kg.