时域电性源地空电磁系统在煤炭采空积水区勘查中的应用

Application of time domain electrical source ground airborne electromagnetic system in goaf water exploration

为实现山区复杂地形条件下,对沁水盆地东南地区煤炭采空区及采空积水区的快速、精确勘查,采用时域电性源地空电磁法对上述区域进行地球物理勘查。时域地空电磁法采用地面发射空中接收的方式,在地面布设接地长导线源,利用大功率发射机向地下发射时域方波信号,在空中利用无人机搭载接收系统沿平行于发射源的预定航线进行飞行探测获取电磁信号和测点坐标信息,发射与接收的电磁数据通过GPS时钟进行同步。利用时域电性源地空电磁探测系统,采集到了信噪比高的电磁数据,同时开展了地空电磁基线校正方法、地空电磁噪声抑制方法及视电阻率成像方法的研究,进一步提升电磁数据的质量和成像分辨率。通过对时域电性源地空电磁数据和空间坐标信息进行处理获得反应测区地电信息时间的电性源地空电磁法视电阻率,结合已知地质信息进行解释,推断解释了煤炭采空区和采空积水区的空间分布特征。时域电性源地空电磁法在极大减少地面工作量的同时,兼顾了勘探深度,因此兼具航空电磁法快速高效和地面电磁法勘探深度大的特征。本次勘查表明:利用该系统开展地空电磁勘查,可以实现工作效率4~5倍的提升,且勘探效果与已知地质信息基本吻合,表明时域电性源地空电磁探测系统可以实现对煤炭采空区的快速、精确勘查。针对本次勘查的效果,可以预期时域电性源地空电磁探测系统将在复杂地形条件下的深部资源探测、环境、工程、灾害地质调查中发挥重要的作用。

In order to realize the fast and accurate exploration of coal mined-out area and goaf water in southeastern Qinshui Basin under complex terrain conditions in mountainous area,a geophysical exploration using time-domain electrical source ground airborne electromagnetic method was conducted in the area above.Time-domain ground airborne electromagnetic method adopts the method of ground launching while air receiving.The long wire source is laid on the ground.High power transmitter is used to transmit time-domain square wave signal to the underground while UAV is used to carry the receiving system along the predetermined route parallel to the launching source for the flight detection and acquisition of electromagnetic signal and coordinate information of measuring points.The electromagnetic data transmitted and received are synchronized by GPS clock.In this paper,the electromagnetic data with high signal-to-noise ratio are collected by using the time-domain electrical source ground airborne electromagnetic detection system.At the same time,the baseline correction method of ground airborne electromagnetic,the suppression method of ground-to-air electromagnetic noise and the apparent resistivity imaging method are used to further improve the quality of electromagnetic data and imaging resolution.The apparent resistivity of ground airborne electromagnetic is obtained by processing the time-domain electrical source electromagnetic data and spatial coordinate information,and the spatial distribution characteristics of mined-out area and goaf water area are deduced and explained by combining the known geological information.The time-domain electrical source ground airborne electromagnetic method not only greatly reduces the workload on the ground,but also takes into account the exploration depth.Therefore,it has the characteristics of fast and efficient airborne electromagnetic method and large exploration depth of surface electromagnetic method.The exploration shows that the system can improve the efficiency by 4-5 times,and the exploration effect is basically consistent with the known geological information.It shows that the time-domain electrical source ground airborne electromagnetic detection system can realize the rapid and accurate exploration of coal mined-out areas.In view of the effect of this exploration,it can be expected that the time-domain electrical source ground airborne elec-tromagnetic detection system will play an important role in deep resources exploration,environment,engineering and disaster geological survey under the complex terrain conditions.