Design And Application Of Array Reception Structure In Coal Mine Underground Detection System

China is rich in coal resources,and Shanxi province is one of the largest coal producing provinces in China,there have been a number of major coal mine accidents in history.Among them,due to the upgrading of underground technology and equipment,production safety awareness,the improvement of the underground ventilation system,the rate of gas explosion accidents showing a downward trend year by year.However,the problem of coal mine water disaster is still one of the main problems which have to be solved.The huge loss of life and property caused by the mine water disaster seriously threatens the safety production of the coal enterprises.Transient electromagnetic method(TEM)has been recognized as one of the most effective methods for the detection of low resistivity in water bodies.But in the complex geological conditions,the traditional receiving device has gradually revealed its drawbacks.Multi-channel receiving method has become one of the main directions to study transient electromagnetic method.In this dissertation,the research status and existing problems of transient electromagnetic method at home and abroad are introduced.On the basis of this,the theoretical basis of the transient electromagnetic method on the ground half space is summarized by studying the generation principle of the secondary field in the transient electromagnetic detection process.By using the similarity between the half space and the whole space,The time depth conversion theory is derived.At the same time,the paper lists various kinds of interference factors and the main working methods used in underground detection.Secondly,this dissertation designs a small coil for multi-channel acquisition system.On the basis of its basic circuit model,through the multi-turn winding,matching resistance to achieve the critical damping state.The received signal is amplified by the terminal.After determining the parameters such as its volume,turns,winding mode and magnification,the basic performance of the multi-turn small coil is verified by the test.Considering the small coil as the core,the multi-channel acquisition system is assembled,the structure design method and the specific instrument parameters are given,and the data acquisition mode in the multi-channel mode is studied.The control software of the data acquisition system in the operation process;the problem of data processing,analysis of the data collected from the processing matters needed attention,expounds the concrete steps of using professional software BETEM and mapping software Surfer.Finally,to the Datong Coal Mine Group Sitai mine,Tashan mine,mountain coal group by Fang ore field detection,Verify its performance indicators.The experimental results show that the multi-channel receiver system has a significant improvement on the detection depth and accuracy compared with the single coil system.