Three-dimensional Numerical And Physical Simulation Study On Advanced Detection By Mine Direct Current Resistivity Method

The mine direct current method is one of the main methods for detecting the waterbearing geological anomaly body in the underground mining face of coal mine.It is widely used to detect the geological anomaly bodies such as the front of heading roadway,the roof and floor of coal seam,the hidden fault fracture zone of roadway sidewall,and the water diversion channel,and plays an important role in the geological guarantee of safe and efficient mining of coal mine.However,the development of advanced detection of mine direct current method is in a bottleneck period,and there are controversial problems such as inaccurate detection targets and small detection distance.It is urgent to study the detection theory and improve the detection method.This paper mainly adopts the method of combining numerical simulation and physical simulation to carry out the advanced detection of mine direct current method.In the numerical simulation part,we mainly study the layered medium model and boundary effect.(1)The influence of roadway cavity on advanced detection is analyzed.The results show that the roadway cavity will lead to high resistance distortion in the first part of the apparent resistivity curve of advanced detection,and the influence of roadway can be effectively eliminated by ratio method.(2)The abnormal response characteristics of the plate and columnar bodies in the uniform whole space are analyzed.The abnormal response of the plate is stronger than that of the columnar body.(3)The abnormal response characteristics of abnormal bodies with different shapes and different electrical properties at different positions under the condition of layered medium are compared.The shape of apparent resistivity curve under the condition of layered medium will change,and the response of layered medium will cover up the response characteristics of abnormal bodies to a certain extent.The identification of abnormal bodies under the condition of layered medium can be realized by extracting the relative anomalies.(4)In the horizontal layered medium space,the change of coal seam resistivity has relatively small influence on the curve shape of low resistivity anomaly body,but has great influence on the high resistivity body.(5)The influence of boundary effect in uniform space is studied.When the calculation area is less than a certain value,the tail branch of apparent resistivity curve will rise up.In numerical simulation,the influence of boundary effect can be avoided by expanding the calculation area.In the physical simulation part,the response characteristics of different shapes,different electrical properties,different sizes and different distances are studied.(1)The roadway model,geological anomaly model and its auxiliary measurement device were constructed.The material of roadway model was made of organic glass,the low resistance model was made of copper plate and copper column,and the high resistance model was made of organic glass plate.The auxiliary device included the hanger of anomaly model and the hoisting beam of roadway model.(2)In physical simulation,the detection effect of low-resistivity body is better than that of high-resistivity body,and the abnormal response of plate-type low-resistivity body is stronger than that of column-type low-resistivity body.The larger the size is,the more obvious the abnormal response is,which is basically consistent with the numerical simulation results.(3)The overall change trend of apparent resistivity curves of physical simulation and numerical simulation is similar,and the detection distance of physical simulation is smaller than that of numerical simulation.