基于槽波的TVSP超前探测方法:可行性研究

TVSP method for reconnaissance beyond coal roadway based on in-seam seismic waves:A feasibility study

针对隧道工程中TVSP(Tunnel Vertical Seismic Profiling)方法不适合于煤矿巷道超前探测的问题,介绍了煤矿巷道中的槽波TVSP超前探测方法原理和实现过程.通过理论和数值模拟证明:(1)当采用垂向集中力源(z方向)激发地震波时,地震波场z分量受到巷道影响较小,且主要为Rayleigh型槽波,较为适合槽波超前探测;(2)采用传播相对稳定且易于识别的槽波埃里相峰值时间代替传统TVSP方法中体波的初至走时时间,能够较准确地确定断层在掌子面前方位置和断层角度;(3)当断层与巷道掘进方向夹角较大时,断层交点位置(断层线与巷道掘进方向的交点)具有很好的定位精度,但角度误差则会较大;当实际断层交点位置距离迎头较远时,断层交点位置定位精度会下降,但角度误差则影响较小;(4)基于槽波的TVSP方法对观测系统要求不高,数据处理过程简单,计算量小.

We introduce a TVSP(Tunnel Vertical Seismic Profiling)technique based on coal seam waves to solve the problems of unsuitable application of conventional TVSP technique in tunnel construction to coal roadway.Some concepts are derived from theoretical analysis and numerical simulations as follows.(1)When a vertical force source(z direction)is employed to excite,the z component wavefield is less affected by roadway and the main energy of z component is Rayleigh seam wave which is suitable for reconnaissance beyond coal roadway.(2)The relatively stable Airy phase time in seismograms is used to determine travel time curves of seam waves instead of the arrivals of waves in conventional TVSP,which results in good accuracy of determination of faults.(3)When the strike angle of a fault is large,the determination of fault position(cross point of the fault line with the roadway drilling direction)has a good accuracy,but it is bad in determination of angle;when the fault is very far from the heading face,the accuracy of position determination decreases,but for the angle,it is little affected.(4)The acquisition geometry of TVSP based on seam waves is simple,the processing of data is not complicated and low computational workload is required.