Application of TEM in Detecting Goaf of Coal Mine with High-resistivity and Shallow-layer

In detecting goaf of coal mine with high-resistivity and shallow-layer,the commonly used method is the high density resistivity method while is TEM is considered to be sensitive for low-resistivity and insensitive for high-resistivity.So the TEM is rarely used.But for Inner mongolia and Shanxi,gullies are well developed on surface,which means that these area do not have the conditions suitable for high density resistivity method.We propose a TEM working method with small coils,high frequency,and great current,which can clearly reflect high-resistivity objective underg round.For those area with changeable land form,the high density resistivity method is unsuitable while the small coil TEM can solve the problem,to a certain degree,of physical detecting in goaf without water.This paper gives a very applicable TEM method for objective,especially for goaf without water and with a shallow buried depth.The calculation of theor etical model is in agrement with actual situation,showing that this method is practical and effective.