煤矿巷道内地震勘探的数值模拟

Numerical simulation of seismic survey in coal mine roadway

用交错网格高阶有限差分波场数值模拟方法模拟了煤矿巷道内点震源激发产生的弹性波场,识别了波场中不同类型的波.分析巷道底部不同深度激发的全空间3分量波场传播的波场特点,结果表明:①在巷道底部激发,巷道顶、底界面引起的混响是巷道内地震勘探的主要干扰波,它严重干扰巷道下方深处煤层的反射;②在巷道底界面以下一定深处激发,混响干扰波大大减少,深部煤层的反射可得到较清楚地显现;③由于SH波偏振和传播的特点,Y-分量波场特别简单清楚,因而用与测线垂直的水平分量检波器接收有可能采集到信噪比高的资料;④巷道内地震勘探分辨率较高,在所设计的模型情况下,可以检测到巷道下方高3 m、宽4 m的空洞.

With the staggered-grid high order finite difference wave field simulation method, simulated the elastic wave field which explosived with point-source in the coal mine roadway, and distinguished different type of waves in the wave field. Compared with the entire spatial three components wave fields propagation characteristics which explosived on or under the roadway in different depths, it indicates that： ① on the roadway base, the reverberation caused by the top and bottom of the roadway （ multiple reflection on the top and bottom of roadway） is the main disturbing wave in the roadway seismic survey, will seriously disturb the reflection of the deep place coal bed underneath the roadway; ② in the several meters depth under the roadway basal bottom boundary, the reverberation disturbing wave is greatly reduced, the reflection caused by deeper coal bed can be detected quite clearly; ③ high signal-to-noise ratio data can be got with Y component detector, for the reason of the SH waves propagation ; ④ get high resolution of seismic data in a roadway, in the model, we can detect 3 meters high and 4 meters wide cavity uderneath the roadway.