Research And Application Of High Density Resistivity Method In The Field Of Heavy Metal Water Pollution

With the improvement of human productivity,environmental problems become more and more prominent,especially the aggravation of air pollution and water pollution.As an important source of human drinking water,the importance of groundwater is self-evident.People pay more and more attention to the protection of groundwater.Geophysics is an interdisciplinary subject.It is a significant direction to use geophysics method to detect groundwater pollution and find pollution sources and paths.It has a broad prospect.As one of geophysical methods,high-density resistivity method has many advantages,such as simple operation,economy,nondestructive detection,reliability,accuracy and so on.High density resistivity method can be used to quickly find pollution sources and pollution paths,and long-term monitoring of pollution paths can be achieved.In order to apply the geophysical method to the treatment of groundwater pollution and the division of groundwater pollution scope,and to provide a better scheme for groundwater pollution treatment,numerical simulation experiment,physical simulation experiment and engineering example verification are carried out.In this paper,the high-density resistivity method is used to simulate the flow and resistivity characteristics of polluted groundwater.According to its principle,the high-density forward modeling software res2 dmod is used to carry out numerical simulation research on different underground models,and then the inversion software of high-density resistivity method is used to carry out inversion on various models,and the inversion map is obtained,and the groundwater flow situation of different strata is analyzed,and the law is obtained After summarizing the rules;on the basis of numerical simulation,the sandbox simulation experiment is carried out.Firstly,the sandbox is stratified.The first layer is crystal sand with a thickness of about 10 cm,the second layer is red clay with a thickness of about 5 cm,and the lowest layer is crystal sand.The main role of red clay is to simulate the isolation layer and fault.For sandbox of different strata,respectively add the pollution source simulated by saturated salt water,respectively measure,the measurement time is about 20 minutes,and then process the measured data,map and explain.Finally,through the detection of waste landfill in Gongxian County,Yibin,through the comparison with the experimental results,determine the high-density resistivity method in groundwater pollution The validity and reliability of dyeing application.The results of numerical simulation show that the flow direction of pollutants in different strata is not the same,and the intuitiveness is not the same.The more pollutants flow,the more intuitionistic the result graph is.The smaller the pollutants are,the more fuzzy the result graph is.For the flow of pollutants under fault conditions,the result chart is intuitive.The physical simulation experiment shows that,because the experimental site is a company,it is not allowed to use the polluted objects such as copper sulfate solution as the pollution source for the physical simulation experiment,so the saturated salt water is used as the pollutant to simulate,its effect is very poor,it can not be displayed on the inversion map intuitively and effectively,which proves that the selection of pollutants is not good.In the case of no problem in stratum stratification and sandbox,it is suggested to have Under the condition,copper sulfate solution and salt were chosen as the pollution source for physical simulation experiment.On the premise of numerical simulation and sandbox physical simulation experiment,a landfill in Gongxian County,Yibin was measured.There are 14 survey lines in the work area,among which L12 survey line cannot be used due to data problems.Firstly,the general trend of underground sewage in landfill is determined by survey lines L5,L6 and L7,then the trend of underground sewage continues to be detected by survey lines L1,L2,L3 and L4 with good effect,and then the trend of underground sewage is determined by survey lines L8,L9,L10,L11,L13 and L14.During the detection process,two flow paths of underground sewage are found,which are shown in the inversion diagram as follows: Low resistivity anomalies in two to three traps.The research results show that the numerical simulation experiment results are good,and the forward modeling results are consistent with the size,shape and resistivity value of the model;however,when the depth of simulated pollutants is large,the forward modeling does not reflect it,because the detection depth of high-density electrical method is limited.In the physical simulation experiment,when sodium chloride solution is added,the resistivity value of the first layer decreases,and the flow path of pollutants is from left to right regardless of whether there is a fault or not,which has a certain correspondence with the numerical simulation experiment.However,because the concentration of sodium chloride solution decreases rapidly after it is added into the sandbox,the experimental effect is not ideal.In the engineering example,each survey line covers the flow road strength of the underground sewage,and the result of inversion is very good.The scope of the underground sewage is clearly shown on the inversion diagram,which corresponds to the numerical simulation experiment.Comprehensive numerical simulation experiment,physical simulation experiment and engineering example,the research has certain significance,can provide theoretical basis and factual basis for the treatment of underground sewage,will save manpower and material resources for the treatment of underground sewage,among which the corresponding effect of numerical simulation and engineering example is the best,the flow path is clear,and the scope is well delineated;physical simulation experiment due to the selection of pollutants However,the effect is not obvious,and further improvement is needed.