直流电势法在探测堤防垂直土工膜埋深中的应用

摘要

垂直铺设土工膜是堤防防渗的重要措施,而土工膜埋设深度是保证堤防防渗的重要指标.但由于地质条件的复杂性及土工膜的隐蔽性,对施作后土工膜仍缺乏有效的无损检测方法.直流电势法基于土体电阻率较小而土工膜相对绝缘的电学特性,探测铺设土工膜土体的电流场和电势场.将双电极对称布置在土工膜两侧,给土体施加电场,测量土工膜两侧各测点的电压.利用COM-SOL数值仿真软件研究不同深度土工膜对电流场和电势场的影响,获得它们之间的规律,采用C语言编制了反演土工膜深度的程序.通过数值方法和室内试验验证,该算法获得土工膜埋深精度在7％范围内,满足工程测量中对土工膜埋设深度检测要求.%Vertical buried geomembrane is an important countermeasure for anti-seepage of levee;its buried depth is an important index to ensure seepage control of embankment.Effective nondestructive testing method for detecting depth of buried geomembrane is still lack due to the complexity of geological conditions and hidden nature of the project.This study is based on the fact that the soil has relatively extremely small resistivity comparing to geomembrane,DC electric potential method is used to detect current field and voltage field of soil with geomembrane.Two electrodes are arranged symmetrically on both sides of the geomembrane to apply electric field to the soill;and voltages on both sides of geomembrane are measured.The influence of geomembrane of different buried depths on electric field is numerically simulated by COMSOL software to get their relativeship;inversion analysis of geomembrane depth is programmed by C language.Through the numerical method and laboratory experiment,the method calculated error of the geomembrane buried depth is less than 5 ％,which meets the engineering requirements for detection of geomembrane buried depth.