可控源音频大地电磁法电阻率与阻抗相位双参数综合判定煤矿双层采空区

Determining double-layer goafs in coal mines using CSAMT-derived apparent resistivity and impedance phase

地下煤层开采后形成的采空及塌陷会给周围生态环境造成破坏,但目前对于煤矿双层采空区,特别是第二层采空区的探测效果并不理想。针对这一难题,采用高效率可控源音频大地电磁仪采集数据,利用电阻率和阻抗相位双参数综合判断划定采空区:当含水采空区位于浅层时呈现低阻特征,电阻率会出现阴影效应,导致上层目标体的异常范围扩展,不利于下层高阻采空区的识别,而阻抗相位的阴影效应和静态效应均比较小,对于下层采空区的反映比较明显。理论模型测试结果表明,电阻率和阻抗相位双参数结合,可有效判定浅部含水采空区和深部未充水高阻采空区。采用该方法,对陕北侏罗纪煤田神府矿区的双层采空区进行了解释,结果表明该方法推断结果可靠,达到了预期勘查效果。该方法为可控源音频大地电磁法在煤矿双层采空区勘查中的应用提供了新思路,具有良好的技术推广价值和借鉴意义。

The goaf and subsidence areas formed ue to the mining of subsurface coal seams can cause damage to surrounding ecological environments.At present,the detection effects of double-layer goafs in coal mines,especially the second-layer goafs,are unsatisfactory.In response to this challenge,this study delineated goafs using apparent resistivity and impedance phase derived from the data acquired by an efficient controllable source audio-frequency magnetotelluric instrument.In the case of a shallow water-bearing goaf with low resistivity,the apparent resistivity displays shadow effects,leading to an extended abnormal range of the upper target,which is unfavorable to the identification of the lower high-resistivity goaf.In contrast,the impedance phase,exhibiting minor shadow and static effects,shows a significant response to the lower goaf.As indicated by the theoretical model testing results,the combination of apparent resistivity and impedance phase can effectively determine shallow water-bearing goafs and deep unfilled high-resistivity goafs.This combination method was employed to interpret the double-layer goaf in the Shenfu mining area of the Jurassic coal field in northern Shaanxi,achieving satisfactory results through the mutual verification of the two parameters.Engineering verification results indicate that this method demonstrates reliable inference and expected exploration effects.Overall,this method provides a new approach for CSAMT-based inference and interpretation in the exploration of double-layer goafs in coal mines,thus holding critical technical promotion and reference significance.