地下供水管线渗漏的探地雷达模拟探测试验分析

Simulated detection experiments of underground water supply pipeline leakage based on ground penetrating radar

地下供水管线作为城市基础设施的重要部分,由于年久失修、腐蚀、施工质量不佳等原因,常常发生管线渗漏及破裂问题。利用无损检测方法准确识别地下供水管线的渗漏位置及影响区域,对其早期预警和后续治理具有重要意义。本文利用探地雷达(GPR)方法对地下供水管线渗漏进行模拟探测试验与分析。首先,基于GeoStudio软件中的SEEP/W模块建立砂土中供水管线渗漏模型并计算其不同渗漏位置和渗漏时间的体积含水量,然后根据Topp公式和电导率与含水量的经验公式构建相应供水管线渗漏的相对介电常数和电导率模型。在此基础上,利用时域有限差分法(FDTD)对不同渗漏位置、不同渗漏时间的供水管线渗漏模型进行GPR模拟探测,并对模拟结果进行分析。最后,开展供水管线渗漏的GPR物理模拟探测试验,并与数值模拟结果进行对比分析。结果表明:与供水管线未渗漏的双曲线绕射波相比,上侧渗漏时,渗漏时间越长,渗漏区域越大,双曲线绕射波出现时间越早,能量越弱,其顶点水平位置保持不变;下侧渗漏时,出现2条分别向上和向下移动的双曲线绕射波,且渗漏时间越长,2条双曲线绕射波能量越弱且越分离,其顶点水平位置保持不变;左(右)侧渗漏时,渗漏时间越长,双曲线绕射波能量越弱,且顶点越向左(右)上偏移。模拟探测研究成果可为供水管线渗漏问题的早期预警和后期治理提供较为可靠的依据。

As an important part of urban infrastructure,underground water supply pipelines frequently leak or break due to disrepair,corrosion,and poor construction quality.It is of great significance to identify the leakage locations and affected areas of underground water supply pipelines using a non-destructive testing method for the purpose of early warning and follow-up treatment.This study conducted simulated detection experiments and analysis of underground water supply pipeline leakage using the ground penetrating radar(GPR)method.Firstly,this study established the leakage model of water supply pipelines in sandy soil using the SEEP/W module in the GeoStudio software and calculated the volumetric water content of different leakage locations and leakage times.Then,it established the relative dielectric constant and conductivity model for water supply pipeline leakage using the Topp equation and the empirical equations of electrical conductivity and water content.On this basis,this study conducted the GPR simulated detection of the water supply pipeline leakage model with different leakage locations and different leakage times using the finite difference time domain(FDTD)method and analyzed the simulation results.Finally,this study conducted the GPR-based physical simulated detection tests of water supply pipeline leakage and compared the test results with the numerical simulation results.The study results are as follows.Compared with the hyperbolic diffracted wave of the water supply pipelines without leakage,that of the water supply pipelines with leakage at different locations are stated as follows.For the leakage on the upper side,a longer leakage area and a larger leakage area were associated with an earlier present hyperbolic diffracted wave with weaker energy,while the horizontal position of the hyperbolic diffracted wave's vertex remained unchanged.For the leakage on the lower side,two hyperbolic diffracted waves appeared,which moved up and down individually.Moreover,a longer leakage time corresponded to two weaker and more separated hyperbolic diffracted waves.The horizontal positions of the hyperbolic diffracted waves'vertexes remained unchanged.For the leakage on the left(right)side,a longer leakage time was associated with a weaker hyperbolic diffracted wave,whose vertex deviated farther toward the upper left(right).The simulated detection results of this study can provide a reliable basis for early warning and follow-up treatment of water supply pipeline leakage.