Dynamic stress characteristics of isolated coal by fault cutting and collaborative pressure relief technology

Abstract

In order to study the stress characteristics of isolated coal body formed by fault cutting, the stress concentration area of isolated coal body can be prevented from impact risk during the mining of the working face. Taking the 6305 working face of Xinjulong Coal Mine as an example, the force estimation model of isolated coal body is established, and the impact risk index Ic is obtained. The collaborative pressure relief technology of “large-diameter drilling pressure relief + blasting cutting roof and pressure relief” is proposed for both sides of the isolated coal body area, and the dynamic stress characteristics of isolated coal body before and after collaborative pressure relief are simulated by FLAC3D. The results show that the impact risk index Ic=2.6>1.5, that is, the average abutment pressure of isolated coal is more than the critical impact threshold. After passing the F311 fault before pressure relief, the mining stress at the XF2 fault side suddenly increases 7.85 MPa, and the impact risk degree increases. After pressure relief, the stress on the mining side of isolated coal body outburst area is reduced by 25.3% on average, and the stress on the non-mining side is reduced by 12.5% on average. There is no large energy microseismic event in the pressure relief area, and the amount of drilling cuttings is normal.

Keywords

• fault cutting
• isolated coal
• mining stress
• microseisms
• coordinated pressure relief