摘要
为研究运行期填埋场深度填埋条件下偶极子渗漏检测和漏洞定位的可行性,通过系统分析运行期填埋场的结构特征和漏洞特征,建立了偶极子检测的概念模型、控制方程和定解条件;基于Comsol Multiphysics高仿真数值模拟软件对上述问题进行有限元求解,并根据现场实测数据对模拟结果进行验证,最后利用该模型讨论了运行期填埋场偶极子漏洞检测和定位的可行性及影响因素.结果表明:数值模型模拟的特征点(极大值点和极小值点)与实际测量点位的y坐标(电势差分值)相对误差最大为24.95%,x坐标(距离)相对误差最大为3.40%,表明模型及其求解方法合理,可用于模拟实际的偶极子检测.在深度填埋(堆体厚度最大15 m)条件下,堆体表面电势差分信号降至m V级别,超出传统铜电极+万用表的检出限.受填埋深度影响,堆体表面电势分布特征与库底电势分布特征差异较大,电势峰值点位置相差达8.0 m,偶极子装置虽可检测出库底漏洞的存在,但是不能准确对其定位(x方向偏移2.0 m,y方向偏移8.0 m).此外,堆体表面的地形起伏会形成伪漏洞信号,干扰漏洞识别;沿测线方向平行移动电极,测线上的漏洞信号也会同时移动,并且关于实际漏洞位置对称.研究显示,在运行期填埋场条件下,传统偶极子漏洞定位方法(即直接根据测线上的异常信号进行漏洞定位)不再适用,但可以通过平行移动地表电极位置,观察地表电极移动过程中疑似漏洞信号的对称中心来进行漏洞定位.
To demonstrate the feasibility of the dipole method in detecting and locating defects of the geomembrane in the bottom of an operating or closed landfill,we constructed a conceptualized model,governing equation and determinate condition of the dipole method for defect location in deeply landfilled sites,and solved the determinate problem using the Finite Element by Comsol Multiphysics software. The numerical model validated by field data was then used to analyze the feasibility of the dipole method in detecting leaks in landfills with several meters of waste, and the influencing factors. The results indicated that the simulated results by numerical model fit the measured data with the relative error of x coordinate smaller than 3.40% and y coordinate smaller than 24.95% ,which means that the model can be used to simulate the actual detection of dinole method and analyze the detection effect and accuracy. 2） In a case study with ten meters oflandfilling waste,the potential signal inland fill surface decreased with landfill depth to the mV level, leading to difficulty of traditional copper electrode and universal meter. The collected potential by the improved dipole devices, though reflecting the existence of the hole,could hardly locate it accurately with 2.0 m deviation in the x direction and 8.0 m deviation in the y direction due to the influence of the waste. In addition, the hypsography of the landfill surface produced pseudo leak signals, leading to interference in detecting and locating the actual defects by traditional dipole method. This research also found that the position of the defect signal in the measure line moved with the position of the surface electrode,and was exactly symmetrical in terms of the actual position. It is therefore suggested that testers move the surface electrode parallel to tile measure line,and locate the actual position of detects in geomembrane by observing the symmetry center of the suspected leak signal.
作者
能昌信
徐亚
刘景财
刘玉强
董路
NAI Changxin XU Ya LIU Jmgcal LIU Yuqiang DONG Lu(Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, Beijing 100012, China College of Water Science, Beijing Normal University, Beijing 100875, China)
出处
《环境科学研究》
EI
CAS
CSSCI
CSCD
北大核心
2016年第9期1344-1351,共8页
Research of Environmental Sciences
基金
国家科技支撑计划项目(2014BAL02B00)
国家环境保护公益性行业科研专项重点项目(201209022)
国家自然科学基金项目(61503219)
关键词
防渗层
土工膜
偶极子
定位
linear layer
gcomembrane
dipole method
leak
location
