土石坝渗漏的波速-电阻率联合成像诊断试验研究

采用模型试验对3种不同渗漏类型的病险土石坝分别进行了波速-电阻率联合成像诊断试验。试验结果表明,采用电阻率成像诊断坝体的渗漏范围具有较高的精度,但在圈定心墙的渗漏通道时,由成像获得的电阻率异常区域较实际渗漏通道大;采用波速成像诊断坝体的渗漏范围时,诊断效果取决于含水率的变化幅度,含水率变化较小的区域,精度较低,但在圈定心墙渗漏通道时,波速成像却具有较高的精度。因此在土石坝渗漏诊断中,采用单一的电阻率成像或波速成像都具有一定局限性,而联合电阻率和波速成像可以有效提高坝体渗漏区域和心墙渗漏通道的诊断精度。

Experimental study on velocity and resistivity combined tomography for diagnosing leakage in earth rock-fill dam

An experimental research on diagnosing leakage location of earth rock-fill dam is illustrated in this paper. The wave velocity and the resistivity tomographic technologies were applied in leakage diagnosis of earth rock-fill dam models with three kind of different leakage type. Based on the analysis of experimental results, some valuable conclusions are obtained. The resistivity is extremely sensitive to the variation of water content of the earth rock-fill dam, and the resistivity imaging has the high precision regarding the diagnosis of dam leakage scope. However, when diagnosing the leakage channel in the core wall, the anomalous region obtained by resistivity imaging is bigger than the actual leakage channel. The effect of wave velocity imaging in diagnosing dam leakage scope is depended on the rangeability of water content, the smaller the water content changes in a region, the lower the precision it is. While for detecting the leakage channel in the core wall, the wave velocity imaging has a higher precision. Therefore, in earth-rockfill dam leakage diagnosis, a single method of resistivity tomography or wave velocity tomography has some limitations, and that combined use of both resistivity and wave velocity tomography can solve the diagnosis problem of dam leakage and the core wall leakage channel well.