Dynamic Monitoring of Mining Destruction on Coal Seam Floor With Constrained Time-Lapse Resistivity Imaging Inversion

Abstract

With the increase in coal mining depth, water hazards in deep, strong karst aquifers have seriously threatened the safety of coal mine production. Dynamic monitoring of floor damage during coal seam mining under complex conditions is of great significance for the prediction of water inrush at the working face and for improving coal mining methods. Based on parallel electrical monitoring technology, a constrained time-lapse resistivity inversion method was adopted to process the electrical data of the working face floor. The background resistivity inversion results were used as an a priori model to act on the inversion of subsequent monitoring resistivity data, and the subsequent inversion results of resistivity were fed back to the prior model, which greatly eliminated inversion artifacts. Finally, the dynamic change process of the resistivity profile before and after the failure of the bottom floor of the mining face was determined, and the maximum depth of the failure zone of the floor is 25m, which is located above the lower aquifer. The field monitoring data show that compared with the method of directly comparing the differences between consecutive monitoring images, the inversion profiles obtained by the constrained time-lapse resistivity inversion method have clearer differences in the spatial and temporal dimensions. The depth of the water-conducting damage zone of the floor was clarified, and the basic development characteristic of the floor damage zone of the working face was obtained, which has practical application value for ensuring the safe mining of the working face.

Keywords

• Coal mining
• direct current monitoring
• time-lapse resistivity inversion
• water-conducting damage zone