瞬变电磁拟MT深度反演方法精细解释煤矿岩层富水性研究

采用瞬变电磁方法探测煤矿水害问题时，经常发现对异常的深度解释不准，很难与实际情况吻合，为解决这一问题，根据瞬变电磁（TEM）延迟时间与大地电磁（MT）周期的对应关系，将实测的TEM数据转化为MT数据，在此基础上，引入了用MT“正演改正法”反演深度的方法。在反演计算的过程中，利用Bostick反演构造初始模型，通过比较初始模型视电阻率与实测视电阻率曲线，依次改正每一个电性层的电阻率和厚度。因为将地下介质划分成与观测时间道数一样多的电性层，在纵向上它能最大限度地反映观测资料所能反映电性层的分辨能力。在MT固有的等值性范围内，“正演改正法”能正确恢复各电性层的电阻率和厚度。通过对理论模型计算和煤矿水害实测资料处理，证明该方法是一种较为精确快速、稳定收敛和实用的方法。

Research on fine interpretation for water containment of coal mine rock strata by MT imitated TEM depth inversion method

When TEM method is applied to detect water problem for coal mines，the interpreted anomaly depth is usually appeared to be inaccurate，which is hardly identical with the actual situation.In order to solve this problem，the measured TEM data was transferred into MT data according to the correspondence relationship between TEM’s delay time and MT’s periods.Based on this，a depth inversion method by MT “forward correction” was introduced in this paper.In the processes of inversion calculation，Bostick inversion was used to build the initial model，then the resistivity and thickness of every electrical layers were corrected successively by comparing the resistivity of initial model and resistivity curve obtained from actual measurement.Since the underground medium was divided into electrical layers in the same number of measurement time channels，it can maximally represents the resolution of electrical layers reflected by the measured data.In the range of MT’s intrinsic equivalence property，“forward correction” is able to recover the resistivity and thickness of each electrical layers.According to analytical model calculation and processing of actual data from coal mine，the method is proved to be an accurate，stable convergence，and practical method.