基于瞬变电磁的采空区含水率评价探讨

Discussion and Evaluation of Goaf Water Ratio Based on Transient Electromagnetic Prospecting

为了利用瞬变电磁法对采空区含水率进行评价分析,采用快速汉克尔变换和Gaver-Stehfest逆拉普拉斯变换对不同深度不同含水率的采空区模型进行了一维正演,以无采空区时的感应电压为基准,计算了不同模型各个测道的感应电压增(降)幅,并拟合了感应电压增(降)幅最值-含水率关系曲线。结果表明深厚比相同时不同含水率采空区的瞬变电磁响应有较大的差异;同一深厚比不同含水率采空区模型的感应电压增(降)幅的最值随含水率单调增加,它们之间的关系可以采用二阶多项式拟合。华北某矿采空区超高水材料注浆治理前后的瞬变电磁响应变化与理论研究结果基本相符,初步验证了瞬变电磁法评价采空区含水率的可行性。

In order to analysis goaf water ratio by using transient electromagnetic prospecting,one dimension direct interpretation for goaf model with different water ration in different depth was proceeded,which faster Hankel transform and Gaver Stehfest inverse Laplace transform was used,it taking induced voltage as base with no goaf,induced voltage variation of all measuring channel of different model were calculated,also fitting the relationship curve between induced voltage variation and water ratio,the results showed that transient electromagnetic response of goaf with different water ratio appeared more difference as deep and thickness was same,the largest value of induced voltage variation at the same deep and thickness ratio appeared monotonically increase with water ratio.Its relation could be fit by second-order polynomial.Transient electromagnetic response variation before and after governing by grouting with ultrahigh water material in one coal mine of north China was conform to theoretical analysis results,its feasibility was verified.