磁共振方法在堤坝渗漏探测中的实验

为精确定位堤坝渗漏点位置，介绍了一种能直接定量探测水的地球物理方法--磁共振法。通过阐述磁共振方法的基本原理和反演算法，确定适用于堤坝渗漏探测的线圈类型和测量方式。采用吉林大学自主研制的JLMRS型磁共振探水仪，在辽宁桓仁崔家街堤坝坝顶铺设4匝边长为12.5 m的正方形线圈，连续测量15个点，测量深度达35 m。经过数据处理和反演解释，得到坝体二维含水量剖面图，为消除上游水体对实验结果的影响提出了修正方法，进而得到坝体二维相对含水量剖面。实验结果表明:崔家街大坝存在3个渗漏点（距溢洪道140、180和240 m处）和2个渗透区（距溢洪道100～150 m和170～250 m处）;深度为-20~-10 m，为砾卵石层渗漏，与工程地质资料和下游渗水情况相符。

Experiment on Dam Leakage Detection with Magnetic Resonance Sounding

To detect the hidden leakage problem of a dam body accurately,a new geophysical method,magnetic resonance sounding(MRS),is introduced,which can directly detect water molecules and quantitatively measure them.The basic principle and inversion method of MRS is research to determine the coil type and measurement mode for dam leakage problem.Field experiment of dam leakage detection was performed on Cuijiajie dam in Huanren,Liaoning Province,using JLMRS system developed by Jilin University.15 points on the dam crest were measured with a 4-rurn square coil of 12.5 m side length for maximum depth 35 m.By data processing and inversing,the water content profile of the dam body in 2D is achieved.Furthermore,for eliminating the effect of upstream water,a correction method is used and the relative water content in 2D is updated.The interpretation results show that there are three leakage points(140 m,180 m and 240 m away from the spillway,respectively) and two infiltration areas(rang of 100 m to 150 m and 170 m to 250 m) at depth of-20 m to-10 m inside Cuijiajie dam,which are gravel layer leakage.The measurement result is confirmed consistent with the engineering geology and downstream water percolation.