Research on the mechanism and prevention of mining induced erosion in the working face affected by fold structures

Abstract

The changes in dip angles of different working faces in the area affected by folding structures cause the variability of mining pressure features. In order to solve the above problem, with the seventh mining area of Baojishan Coal Mine as the engineering background, a combination of on-site research, theoretical analysis, numerical simulation, and on-site industrial experiments is used. The dynamic and static loads during mining of different working faces in coal seams with varying dip angles are studied. The results indicate the following points. ① The accumulated acoustic emission(AE) energy of the coal rock composite system with a stiffness value greater than 0 is smaller than that of the coal rock composite system with a stiffness value less than 0. This indicates that when the stiffness value of the coal rock composite system is less than 0, AE energy is more likely to accumulate. When the stiffness value of the coal rock composite system is less than 0, the larger its absolute value, the higher the AE energy can be accumulated. ② As the dip angle of the coal seam increases, the concentrated static load inside the solid coal side of the goaf roadway decreases, and the concentrated static load inside the coal pillar side increases. The hanging top section required for the cracking of the high and thick hard key layer is longer. ③ When the dip angle of the coal seam is small, the combined system of coal and rock in the two sides of the goaf roadway is prone to inducing dynamic failure type II rock burst under the combined action of dynamic and static loads. When the dip angle of the coal seam is large, the coal rock combination system inside the coal pillar side of the goaf roadway is prone to inducing static or dynamic failure type I rock burst under high concentrated static load. ④ During the mining period of the 705 fully mechanized top coal caving face, the coal pillar side of the goaf roadway is prone to inducing static or dynamic failure type I rock burst. After implementing anti erosion measures, the electromagnetic radiation value decreases by up to 67.3%. The coal rock combination system is not easy to induce rock burst.

Keywords

• coal seam mining
• fold structure
• coal seam dip angle
• rock burst
• near field dynamic load disturbance
• far field dynamic load disturbance