矿井瞬变电磁法低阻体的全空间响应影响研究

基于矿井瞬变电磁法全空间效应会增加低阻体空间定位的难度,易误判地质异常发育的位置,为提高解释精度,准确得出地质异常发育的位置,基于电磁场扩散理论,建立井下瞬变电磁场正演模型,采用9点扇形探测法,研究了矿井低阻体对电磁场全空间分布的影响规律,提出了全空间地质体校正系数,并在祁东煤矿进行了试验。结果表明：当顶底板均有低阻体时最大感应电位的数量级达107,比底板单有低阻体时高1个数量级,此时单支曲线尾支衰减更平缓,可得到校正系数0.2～0.6;底板探测低阻区域视电阻率为10Ω.m,经校正后升至25Ω.m,呈高阻反映,钻孔验证无水,证明该区域不存在低阻异常发育。

Study on Mine Transient Electromagnetic Method Affected to Full Space Response of Low Resistance Body

The full space effect of the minetransient electromagnetic method would increase the space positioning difficulty of the low resistance geological mass and would misjudge the location of the geological abnormal development.In order to improve the explanation accuracy and accurately obtain the location of the geological abnormal development,based on the diffusion theory of the electromagnetic field,a forward model of the mine transient electromagnetic field was established.A nine sector detection method was applied to study the influence law of the mine low resistance mass to the full space distribution of the electromagnetic field.The correction coefficient of the full space geological mass was provided and the test was conducted in Qidong Mine.The results showed that when the roof and floor both had the low resistance mass,the magnitude order of the max induced potential was 107 and would be one magnitude order higher than the floor with the low resistance mass only.At this moment,the decay of the single curve tailrace would be more gently and the correction coefficient would be 0.2~0.6.The apparent resistivity of the low resistance region detected in the floor was 10 Ω·m and could increase to 25 Ω·m after the correction.The apparent resistivity would be high resistance in reflection.The borehole was no water as confirmed and there was no low resistance abnormal development in the region.