回采工作面复杂陷落柱全波形反演及应用

Full-waveform inversion and its application in imaging of complex collapse columns in coal seam floor

深部开采受底板承压水威胁大,近年来底板陷落柱突水事故频发,但现有的地震勘探技术难以精细查明复杂陷落柱的弹性参数.本文建立了大小尺度、长轴方向多变的组合复杂陷落柱模型,利用回采工作面底板的理论合成体波数据,开展适用性更好的卷积目标函数的弹性波全波形反演成像研究,结果表明:全波形反演技术能够探测出复杂陷落柱,成像结果与理论模型的吻合度高;对比纵横波成像结果,由于横波的波长短,所以反演结果分辨率更高,对小尺度陷落柱成像具有潜在优势;较小道间距观测系统能够更好地刻画陷落柱的形态,即使较大道间距的情况下,纵横波联合可以解释小陷落柱;同时,相比于“I”型观测系统,采用包围性更好的“L”型观测系统可以提高成像精度.最后,首次开展了工作面底板的现场数据全波形反演应用,并取得较好效果.

Deep mining is greatly threatened by floor pressurized water.Water inrush disasters resulting from floor collapse columns have occurred frequently in recent years.However,it is difficult for the existing seismic exploration technologies to accurately ascertain the elastic parameters of complex collapse columns.In this paper,a complex model is established by combining collapse columns with variable size and long-axis direction,and a more functional elastic full-waveform inversion with convolutional objective function is employed to test on the theoretically synthesized body-wave data of the mining working face.The results show that the full-waveform inversion technology can detect complex collapse columns,and the imaging results are in good agreement with the theoretical model.Compared with the longitudinal and transverse wave imaging results,the inversion results of transverse wave have a higher resolution due to its shorter wavelength,so that transverse wave has potential advantages for small-size collapse column imaging.The geometry with a smaller trace space can better describe the shape of the collapse columns,and the combination of longitudinal and transverse wave images can explain the small-size collapse columns even with large trace spaces.At the same time,the L-type geometry with better coverage can improve imaging accuracy compared with the I-type geometry.Finally,the full-waveform inversion application of working face floor field data is carried out for the first time,and good results are obtained.