Research On Detection Technology Of Ground-Tunnel DC Electrical Method

Exploring and finding out fault and subsided column and goaf water bearing structures of under Ground-Tunnel is the most important of mine water control work. Mine DC method has become one of the main methods of mine hydro geophysical exploration, affected by underground construction environment, it still can’t fully meet the requirements of precise detection. In this view, the paper puts forward a kind of Ground-Tunnel DC electrical method which arrange the power supply electrode on the ground and measuring electrode in the under Ground-Tunnel.On the basis of the traditional electrical equipment type, the working mode of Ground-Tunnel DC method is proposed, some improvements and advantages compared to the traditional electrical method are described, based on the fundamental equation of dipole source current field, the field distribution equation of the sphere model is derived, and the electric field response characteristics of ground power supply and measured in tunnel are studied.By the use of COMSOL simulation software, the response characteristics of typical water conductive structure in stable current field of ground power supply and measurement in tunnel are simulated: we studied the potential response of the background field, the spatial background field of tunnel, spherical and plate anomalous body in different directions of tunnel. The simulation results show that the low resistivity and high resistivity both have a good response to the detection potential profile, and the response of low resistivity anomalous is much more obvious. According to the results, in theory, mine Ground-Tunnel DC method is feasibility for detecting water bearing structures in the tunnel.According to the comparability theory of physical simulation, we do the physical simulation experiment in the laboratory. For the physical simulation, we select the sand and water to be background to simulate abnormal response of typical anomalous bodies which are simulated by copper bar and PC board. The results show the similar rules to numerical simulation.Besides, we carried out the actual detection test in a coal mine in Shuozhou, Shanxi by the Ground-Tunnel DC method. As a result, the measured apparent resistivity data and the polarization data have effective indications of goaf with water. Hence, actual detecting proves feasibility of the method.