A novel detection method of mining subsidence area based on the inequality constrained inversion of borehole-to-surface electrical (BTSE) technology

Borehole-to-surface electrical (BTSE) technology plays an important role in detecting mining subsidence area in coalfields. However, the ambiguity of linear inversion and the influence of surrounding rock resistivity reduced the effectiveness and accuracy of BTSE technology in identifying mining subsidence area. In this study, the damped least-squares inversion method constrained by inequality was investigated based on the basic principles of BTSE technology. On this basis, a novel method using the ratio of post- to pre-mining inversion resistivity was proposed to detect mining subsidence area. Finally, the application effect of this method was analyzed by using theoretical model and laboratory mining model, respectively. It was found that the resistivity inversion of the BTSE constrained by inequality could obtain good layered information of the stratum provided by prior information. Using the ratio of post- to pre-mining inversion resistivity can eliminate the influence of surrounding rock on the abnormal resistivity and highlight the resistivity anomalies caused by stratum collapse during coal mining. The application results of the theoretical model and laboratory mining model illustrated the feasibility and effectiveness of this novel method in detecting mining subsidence area, which provides important theoretical basis and reference for its future promotion and application.