基于震波CT探测的宽煤柱冲击地压防控技术

针对深井区段煤柱冲击地压易发、多发、难防治的难题，以某矿1301工作面80 m区段宽煤柱冲击地压为例，利用数值模拟及微震数据分析，研究了宽煤柱冲击地压致灾机制，采用震波CT原位探测技术评估了宽煤柱区域内冲击危险性，并提出针对性防治方案。结果表明:3号煤层具有弱冲击倾向性，顶板岩层具有强冲击倾向性，已具备发生冲击地压的内在条件，高自重应力、强构造应力提供了基础静载荷，采空区侧向支承压力提供了增量静载荷，当两者叠加导致垂直应力超过冲击临界支承压力时，为宽煤柱静载荷冲击地压的发生提供了力源条件;震波CT原位探测技术以穿透煤岩体的实际震动波射线进行波速反演，反映煤岩体静载荷分布特征及结构特性，建立了以波速异常系数CA和波速梯度系数CG为主要因子的冲击地压危险性评估模型;鉴于宽煤柱冲击区域采掘空间实际条件，设计布置近完全观测系统观测方式，采用震波CT原位探测技术反演评估得到宽煤柱测区内冲击危险指数C=0.5~0.7，表明冲击发生后，宽煤柱仍然存在静载荷集中区域，具有中等冲击危险，并且运输巷侧冲击危险指数较采空区侧高，表明煤柱应力由采空区侧向运输巷侧转移，局部区域煤体破碎易冒顶片帮;制定了基于静载荷疏导的多层次防冲技术:大直径钻孔预卸压转移巷帮集中应力，耗散弹性应变能，确定合理日进尺为2.4 m，降低开采扰动，巷道全断面补强支护，提高围岩抗冲击能力;通过上述措施，现场监测宽煤柱煤体应力未发生突增，微震能量及频次变化平缓，1301工作面已安全回采宽煤柱区，防治效果显著。

Rock burst prevention technology based on seismic CT detection in wide section coal pillar

To overcome the problems of easy occurrence,frequent occurrence and difficult prevention of coal pillar rock burst in deep mine,taking the rock burst in 1301 roadway with 80 m wide coal pillar as an example,based on numerical simulation and microseism data analysis,the mechanism of rock burst in wide coal pillar was studied.The seismic CT in situ detection technology was used to evaluate the risk of rock burst,and the corresponding prevention and control scheme was put forward.The results show that the weak burst tendency of No.3 coal seam and the strong burst tendency of roof rock stratum were the intrinsic condition of rock burst,the high gravity stress and strong tectonic stress were basic static loads,and the lateral abutment pressure of goaf was incremental static loads.When the vertical stress exceeded the critical abutment pressure,it provided the force source condition for the occurrence of static load type rock burst in wide coal pillar.By inversing the wave velocity from the actual seismic wave rays,the seismic CT in situ detection technology can reflect the distribution and structural characteristics of the static load,and establish a risk assessment model of rock burst with the abnormal coefficient of wave velocity CA and the gradient coefficient of wave velocity CG as the main factors.In terms of the actual mining conditions in the impact area of wide coal pillar,a near complete observation system was designed and arranged.The seismic CT detection showed that after the occurrence,the burst hazard indices were C=0.5-0.7 and had moderate degree burst hazard,the burst hazard index of the side of transport channel was higher than that of goaf,which indicated that the stress of coal pillar had transferred from the side of goaf to the side of transport channel.The local fractured zone had high risk of roof caving or rib spalling accident.The multi level prevention and control technologies based on static load transformation were formulated including a large diameter borehole pre relief technology was used to transfer concentrated stress and dissipate elastic strain energy of roadway side;the 2.4 m/d advancing speed of working face was determined to reduce mining disturbance;and the support reinforcement of full roadway section was designed to improve the anti impact ability.Through the above measures,the monitoring stress did not occur sudden increase,and the microseism energy and frequency was gentle.In 1301 working face,the wide coal pillar area had safely been recovered,and the control effect was obvious.