Study On Forward And Inversion Of Resistivity Method For Monitoring Pollution Diffusion In Hazardous Waste Landfills

Leakage in hazardous waste landfills will pose an indelible threat to the surrounding ecology and human health.In China,there is still no effective monitoring and investigation of hazardous waste landfills.With the continuous improvement of people’s awareness of environmental protection,more and more scholars focus on the field of the monitoring of hazardous waste landfills’ pollution diffusion sites.The resistivity method is a very impor-tant branch in the geophysical exploration field.It has been widely used in the fields of hydrology,environment,oil and gas exploration,and mineral survey due to its advantages such as nondestructive,high spatial and temporal resolution,and low environmental impact Because the leachate usually contains a variety of ions,heavy metals,and other toxic and harmful substances in the landfill pollution diffusion,which will cause a difference in the re-sistivity of the contaminated area,the resistivity method can be used to observe and explain the distribution law of man-made electric field to carry out pollution diffusion monitoring of hazardous waste landfill sites.This paper aims to improve the calculation accuracy of the traditional forward and inverse resistivity method,monitor the pollution diffusion in time and control the pollution in the budBased on the above analysis,the forward and inverse method of resistivity method based on the finite element method and Gauss-Newton inversion is proposed in this paper,and study the feasibility of the algorithm.It was verified at a hazardous waste landfill site in Yancheng from the field scale to realize the monitoring work of pollution diffusion.The main work of this paper includes:(1)The variational problem of the three-dimensional stable current field is deduced,the hexahedral element is used to divide the research area,and the linear equations of the three-dimensional finite element method.The generalized minimum residual algorithm(GMRES)is used to avoid the storage and direct solution of the large sparse linear equa-tions in the three-dimensional finite element method,which reduces the calculation cost and improves the calculation accuracy(2)The theoretical basis of the inversion algorithm for linearizing nonlinear problems is studied deeply,Gaussian-Newton method is used to optimize the inversion of model parameters,and constraints such as regularization parameters and smooth constraint matrix are added to the objective function to improve the inversion accuracy.The Jacobian-free Krylov subspace technique is used to calculate the Jacobian matrix,which greatly reduces the time needed to generate and solve the Jacobian matrix(3)The detection electrode was laid outside the flexible vertical anti-seepage curtain of the hazardous waste landfill in Yancheng and sampled regularly.The sampling data was used for resistivity inversion imaging to analyze the pollution diffusion and is verified by AGI inversion software.Verifying from the field scale proves that the algorithm is effective in monitoring the pollution diffusion of hazardous waste landfillsThe research in this paper shows that the resistivity forward and reverse method has high accuracy in the field of hazardous waste landfill pollution diffusion,which provides some reference experience for future research.