| Groundwater resources are scarce,and rainfall is the main supplement source in loess areas.Water content and matric suction of soil change with seepage flow during rainfall,which affects of loess slope stability.So rainfall is an important cause inducing landslides.Studying the infiltration mechanism of unsaturated loess and water transport characteristics can provide reference for the prevention and control of rainfall-induced landslides in the loess regions,and also provide basic theoretical support for water migration and distribution related to irrigation,groundwater recharge and so on.Soil is a typical three-phase material.Water is an important component of soil.As a connector of surface water and ground water,it plays an important part of the natural water cycle system.To understand the migration and infiltration process and characteristics of water in the soil,loess column infiltration tests were conducted based on high density electrical resistivity tomography(ERT),and WDJD-3multifunction digital DC exciter was adopt to measure the soil resistivity during infiltration.And the relationship between resistivity and water content is analyzed combined with volumetric water content obtained from the tests and water migration characteristics are quantitatively studied.The HYDRUS-1D software was applied to simulate the infiltration characteristics,and the applicability of high density resistivity tomography method in monitoring migration process of soil moisture was verified.The main results obtained in the paper are as follows:(1)The influence of variation in water content,pore fluid composition and dry density on the resistivity of remolded loess was studied by orthogonal tests and the main factors are analyzed.The expanded Archie formula was used to fit the measured resistivity values under different dry densities to analyze its applicability.(2)According to the experimental results,related variables were controlled,and infiltration tests of remolded loess column were conducted based on ERT.The variations characteristics of volumetric water content,matrix suction and resistivity,as well as the infiltration rate,cumulative infiltration and infiltration were analyzed,so that the infiltration characteristics of unsaturated remolded loess could be understood.Based on the experimental results and the G-A infiltration model,the two-step infiltration model of remolded loess is developed to calculate the deviation between the calculated and measured value is analyzed.Estimate the accuracy of infiltration model calculation.(3)The model between the measured apparent electrical resistivity,volumetric moisture content and matrix suction is established.Based on the apparent resistivity model-volume moisture content,volumetric moisture content profiles are obtained by SURFER11.0 software.The infiltration process of loess column in the experiments were simulated by HYDRUS-1D software to obtain the temporal and spatial characteristics of water content variations of the soil column.And the results are compared with the volumetric water content profiles obtained from ERT to verify the accuracy and applicability of ERT for monitoring the infiltration process. |
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