煤矿采空区积水瞬变电磁法探测方法优化

Optimization of transient electromagnetic method for detection of water accumulation in coal mine goaf

应用矿井瞬变电磁法进行含水异常体的探测效果明显,但容易受到巷道复杂工程地质条件和设备环境的干扰,需要进行针对性优化以提高矿井瞬变电磁法信号采集质量和解释精度。基于“烟圈”扩散理论,阐述了矿井瞬变电磁法探测原理及视电阻率纵向微分解释方法;通过对已知积水采空区进行瞬变电磁法探测试验,分析对比了主要采集参数对瞬变电磁法电场响应特征的影响;结合视电阻率纵向微分解释方法,提出了矿井瞬变电磁法采空区积水探测的数据采集与处理优化方案并对其进行了效果评价。结果表明:线圈与巷道围岩之间距离越近,两者耦合程度越高,且该距离存在合理范围,超出该范围线圈接收到的电压响应值过低,不满足数据对信噪比的要求;增加叠加次数可提高信噪比,并有效压制电压衰减曲线尾支畸变;适用于高家梁煤矿的合理距离范围为0~0.5 m,叠加次数为64次。

Mine transient electromagnetic method(MTEM)is a great method to detect abnormal water body,but it is easy to be disturbed by the complex engineering geological conditions of the roadway and the equipment environment.Therefore,targeted optimization is necessary to enhance the data acquisition quality and interpretation accuracy.Based on the“smoke ring”diffusion theory,the detection principle of transient electromagnetic method and the vertical differential interpretation method of apparent resistivity are expounded.The influence of the main acquisition parameters on the electric field response characteristics of TEM is analyzed and compared through the transient electromagnetic detection test of known water accumulation in goaf;combined with the vertical differential interpretation method of apparent resistivity,a data acquisition and processing optimization scheme of mine mined-out water detection by transient electromagnetic method is proposed and its effect is evaluated.The results show that the closer the distance between the coil and the roadway surrounding rock,the higher the coupling degree between them,and there is a reasonable range of the distance,beyond which the voltage response received by the coil is too low,which does not meet the requirements of the data on the signal-to-noise ratio.Increasing the stacking times can improve the signal-to-noise ratio and effectively suppress the distortion of the tail branch of the voltage attenuation curve.The reasonable distance range applicable to Gaojialiang Coal Mine is 0-0.5 m,and the stacking times are 64 times.