Dynamic detection of water in a working face floor using cross-inclined borehole Electrical Resistivity Tomography (ERT)

Abstract

A dynamic detection system was established by cross-inclined borehole electrical resistivity tomography (ERT), in order to monitor the water flow in Ordivician limestone (0LS) during development process of working face. The following approaches were adopted by the detection system. First, two inclined boreholes were constructed in the transportation roadway, and the metal joints of the cables were coupled to the surrounding rock of the boreholes by attaching the cables to metal sheets and grouting. Second, with a self-designed cable protection device, the cables were led out of the borehole to prevent the cables from being damaged by high-pressure grouting. Finally, supporting trenches were established in the transportation tunnel to prevent the cables from breaking down due to the falling of rock from the roof. During the development process of working face, data were acquired in five times. Combined with the distribution of the mine pressure and hydrogeological conditions, the abnormal areas with a low resistivity were accurately interpreted from the detection results, providing an early warning for the water inrush events from the floor.