利用综合物探方法探察山区河床地质条件

河流河床地下空间地质条件是地下管道等隐伏工程跨河段施工的关键,必须对其下伏岩层条件及其含水性、岩层破碎特征等进行超前探察与判断。基于并行电法探察技术,构建河床地质条件计算模型,利用正反演方法得出河床模型地断面的电性特征,并利用瑞雷面波辅助实施综合探察。通过现场工程应用,综合探察取得了良好的应用效果,试验区内岩层受河流侵蚀比较明显,河流的渗流范围大,宽30 m、深度在20 m左右,测区内破碎带呈条带状分布,范围较大,厚度不一,深度在10~15 m的范围内,物探解释与钻孔揭示地层条件对应一致性好。研究结果表明,综合物探方法能够有效探察山区河床地层的分层性、层厚、分布范围、河流的渗透范围等地质条件,为河床下伏工程施工技术措施制定提供依据。

Comprehensive geophysical prospecting method to explore the geological conditions of the river bed in mountainous area

Based on the exploration technique of parallel electrical method， the calculation model for geological condition under riverbed is established herein， and then the electric characteristics of the geoelectric cross-section of the riverbed model are obtained with forward and inversion methods， while the comprehensive exploration is carried out with the assistance of Rayleigh wave technique. Through the in situ engineering application， better application effect is got from the comprehensive exploration. The exploration indicates that within the experimental area， the erosion of the rock-stratum from river is more obvious and the range of the seepage from river is larger with the width of 30 m and depth of about 20 m， while the fracture zone with a depth in a range of 10~15 m presents a belted distribution therein with larger range and various thicknesses， for which better consistency between the formation conditions revealed by both the geophysical interpretation and the drilling hole exploration is obtained. The study result shows that the comprehensive geophysical prospecting method can effectively explore the geological conditions of the strata under riverbed within mountain area， i.e. stratification， stratum thickness， distribution area， seepage range of river， etc.， and thus provide a basis for making the technical measures for the construction of the project under river bed.