瞬变电磁法定量评估河流流域开采区富水性技术

为了查明河流下渗对露井联采采空区和回填区影响的范围及程度,采用瞬变电磁法对鄂尔多斯呼和乌素沟与乌兰木伦河附近井工开采采空区及露天开采回填区进行探测试验,根据距离河流的远近不同从"线、面、体"等角度全方位分析电性响应特征情况,并结合物探区域内钻探抽水试验结果,探讨瞬变电磁法定量探测富水性的可行性。结果表明:瞬变电磁法可精确勘查河流流域露井协采煤矿浅埋深地质异常体(埋深不超过150 m)富水范围及强度,河流附近不含水(或弱含水)采空区高阻特征明显,而河流附近含水回填区低阻特征明显;附近河流对回填区影响较大,横向可达500 m,回填区呈现明显的富水"漏斗",横向影响范围随深度增加缩小,富水强度随深度增加也减弱,基本与露天剥离回填空间范围相吻合,而附近河流对采空区及上部岩层影响较小,横向不超过80 m,纵向主要影响采空区上部含水层,对采空区补给较少,采空区基本不含水(或弱含水);尝试建立钻孔单位涌水量与视电阻率之间的关系式,并用瞬变电磁法定量探测区域单位涌水量从而确定富水性等级。

Quantitative assessment of water richness in mining area of river basin by transient electromagnetic method

In order to ascertain the scope and extent of the impact river infiltration on the exposed goaf and backfill area, we used the transient electromagnetic method to detect underground mining goaf and open-pit mining backfill near the Huhe Wusu Ditch and Ulan Moron in Ordos. According to the different distance from the river, the electrical response characteristics were analyzed from the unidimensional, planar, and three-dimensional perspectives. Combined with the results of drilling pumping test in the geophysical exploration area, the feasibility of quantitative detection of water richness by transient electromagnetic method was discussed. The results show that the transient electromagnetic method can accurately survey the water-rich range and intensity of geological anomalies at a shallow buried depth not exceeding 150 m in the river basin. The high-resistance characteristics of the non-aqueous (or weakly-water-bearing) goaf near the river are obvious while the low-resistance characteristics of the water-filled backfill near the river are also obvious. The nearby rivers had a great influence on the backfilling area, to the lateral distance up to 500 m. The backfilling area presented a clear water-rich "funnel". Both the lateral influence range and the water-rich intensity decreased with depth, which was basically consistent with the space scope of the open-air stripping backfill. And the nearby rivers had less impact on the goaf and the upper rock with the lateral distance less than 80 m, vertically mainly affecting the upper aquifer of the goaf, and the goaf was basically free of water, or weakly aquiferous. The relationship between the unit water inflow and the apparent resistivity of the drilling was established, and the use of transient electromagnetic method to quantitatively detect the unit water inflow and water-richness level was explored.