Application of TEM on Detecting Goaf of Coal Mine without Water in Complex Terrains

In view of the fact that while detect the coal mine goaf without water,high density direct current resistivity method has strict requirements for the terrain,for the coal area that surface condition is relatively complex and terrain undulating is large,the research and application of the TEM use special parameters which reflect the electrical characteristics of coal mine goaf without water have practical significance.Thus,starting from the basic principle of transient electromagnetic method,this paper introduces the basic formula of the transient electromagnetic method and modeling method at first.Then combining with the geophysical characteristics of the goaf without water,we designed the forward model.And then based on the results of calculation,we presented that in the area with complex terrain conditions and are not suitable for the construction the high density resistivity method,we can adopt the transient electromagnetic method,which with flyer frame,high firing frequency and large emission current,to detect the electrical characteristics of high resistance target of underground,so that we can inference the distribution of the goaf without water.Finally,combined with practical engineering to practice the transient electromagnetic method for detecting the coal mine goaf without water,and the conclusion is consistent with actual drilling results.The results of application show that the transient electromagnetic method can finish the detection for the coal mine goaf without water in a certain degree,and it plays a reference role for coal mine safety.