基于时间域电磁法的地下采空区探测

Detection of underground goaf based on time-domain electromagnetic method

时间域电磁法基于电磁感应原理,向地下发送双极性方波电流,在双极性方波电流关断瞬间,利用线圈观测二次涡流场,通过分析处理二次场信号,就可以获得地下电阻率分布,从而获得地下介质信息。当地下局部煤层被采出形成采空区后,由于地下水的填充及地表水的渗漏,导致采空区与围岩电阻率形成明显差异,这就为利用时间域电磁法进行采空区探测提供了物理前提。本文在这个物理前提下,首先介绍了时间域电磁法发射系统关键技术,旨在说明双极性脉冲电流产生方法,然后通过设计采空区模型,利用理论计算进一步证明了利用时间域电磁法进行采空区探测的可行性。

Time domain according to the time-domain electromagnetic method on the basis of the principle of electromagnetic induction,the bipolar pulse current is sent into the underground.In a flash of turning the pulse current off,the secondary turbulence field can be observed by means of induction coil or grounding electrode.Then,by analyzing and processing the secondary signal,the distribution of underground resistivity can be gained,underground media information included.After partial coalseams are mined,goaf come into being.Since the goaf fill with underground percolating water,the goaf and the surrounding rocks are obviously different in resistivity,which makes it physically possible to detect underground goaf by adopting the time-domain electromagnetic method.The paper introduces the key technology of the time-domain electromagnetic emission system to explain the method of generating the bipolar pulse current and further to prove it is practicable to detect underground goaf using the-timedomain electromagnetic method by designing the goaf model and calculating theoretically.