基于双电极法的土工膜缺陷探测数值模拟

利用电场与渗流场控制方程及边界条件相似的原理,对含缺陷的防渗土工膜上的电位分布进行有限元模拟,获得缺陷附近的电位分布特征,进而判断缺陷位置。此外,对电极埋设位置、施加电压值和探测间距等因素进行敏感性分析。计算结果表明:双电极法可有效确定土工膜缺陷位置,土工膜缺陷越靠近励磁电源电极,越有利于缺陷的准确探测;沿着缺陷中心线方向进行探测,可高效探测缺陷位置;移动探测仪的电极间距应以探测长度的5%~10%为宜。研究成果对双电极法用于土工膜缺陷探测有理论指导意义。

Numerical Simulation of Defect Detection of Geomembrane Based on Dual-electrode Method

In the light of the similarity of governing equation and boundary condition between electric field and seepage field, the potential distribution on the surface of defective impermeable geomembrane was simulated via finite element approach. The anomaly potential distributions in the vicinity of defect were obtained to determine the location of defect. In addition, sensitivity analysis of the buried position of electrode, excitation voltage, and dipole spacing were taken into account. The computed results demonstrate that the defect in the geomembrane can be accurately located by using pole-dipole electrical survey methods. The detection of defect is more effective for a closer distance between the defect and the electrode; the detection efficiency can be increased when the detective line is along the center line of defect. The results also show that the dipole spacing of 5%-10% of the length of survey line is appropriate for detecting the defect in geomembrane. The calculated results are of theoretical guiding significance for the application of pole-dipole electrical survey methods to the detection of geomembrane defect.