Research On Leakage Location Method Of Landfill Based On Stress Wave Detection Technology

With the continuous expansion of China's urban scale,the number of urban domestic waste landfills has also increased year by year.In order to prevent the landfill leachate from causing secondary damage to the surrounding environment of the landfill,the landfill must establish a complete anti-seepage system.At present,the main material of the landfill anti-seepage layer is High Density Polyethylene(HDPE)film.However,due to the effects of virtual welding,leakage welding and geological changes in the soil layer around the landfill during the installation of HDPE film,leachate leakage will occur in the landfill during operation.Therefore,how to quickly and accurately locate the antiseepage layer of landfill has become a problem that researchers have to face.The leakage detection principle of the traditional landfill anti-seepage layer is that after the HDPE membrane leaks,the leachate will change the electrical parameters of the soil,and then the leakage point coordinates will be located by detecting the change of the conductivity of the soil layer under the membrane.Therefore,when the detection system finds a leak,the leachate has caused serious damage to the surrounding environment of the landfill.In this regard,this paper proposes a landfill leak detection method based on HDPE film rupture signal picking.The stress wave sensor can identify and extract the stress wave signal generated by the HDPE film rupture moment,which can realize the rupture of HDPE film.At one time,the damage point of the anti-seepage layer is positioned,thereby solving the problem of the traditional method of “contaminating first,then discovering”.The main research contents of the thesis are as follows:(1)The stress wave propagation principle and stress wave detection theory are analyzed.Combined with the HDPE film fracture mechanism research and the main frequency characteristics of HDPE film rupture signal,the landfill leakage location method based on HDPE film rupture signal pick-up is established.According to the HDPE membrane rupture mechanism and the relevant engineering requirements of landfill leakage detection,the method of arranging the stress wave sensor in the locating model is studied.(2)In detail,the simulation study on improving the performance of the leak detection system is studied in detail.For the signal strength resolution of the system,a stress wave signal preprocessing method based on the LMS adaptive filtering algorithm is used,and the filtering model can be known through simulation experiments.The performance is inversely proportional to the step factor and proportional to the order of the filter.At the same time,an improved model for picking up the stress wave from the first arrival of the stress wave method combined with the weighting factor correction method is proposed according to the system's requirements for time resolution,and experimental research is conducted.It was analyzed and verified..(3)The related hardware and software design of the landfill leakage detection system based on the stress wave detection technology is implemented to identify and extract the HDPE film rupture signal;and carry out the detection system based on the actual engineering situation The experimental verification shows that the maximum reference positioning errors of the positioning model in the X-axis and Y-axis directions are 0.32% and 0.58%,respectively,and all the errors meet the engineering requirements for leakage positioning.