Study On Monitoring Water Content Of Loess Based On Geoelectric Field Detection

In this paper,the unsaturated loess in Heifangtai,Yongjing,Gansu Province is taken as the research object.Through the indoor one-dimensional resistivity test,the differences between two-phase electrode method and four phase electrode method,DC power supply and AC power supply are compared,the time characteristics of resistivity are analyzed,the ways to improve the accuracy of loess resistivity test are discussed,and the relationship between the Loess resistivity and its water content is obtained.On this basis,the high-density electrical method monitoring and sensor monitoring were carried out in Heifangtai,the continuous soil resistivity data and soil moisture data of the study section were obtained,and then the water content profile was obtained,and the influence of water content change on slope stability was discussed.The conclusions are as follows:(1)The results of the one-dimensional resistivity experiment show that with the increase of test time,the four phase electrode method is more reliable than the two-phase electrode method.Through reasonable control of charge and discharge time,DC test can get the same test results as AC resistivity test.(2)In the process of moisture absorption and dehumidification,the moisture content of loess has an exponential relationship with the resistivity,both of which have a good correlation.Under the same moisture content,the resistivity of moisture absorption process is larger than that of dehumidification process,and there is obvious hysteresis effect.(3)The high-density electrical method equipment suitable for long-term field monitoring is developed for field monitoring.Through reasonable arrangement of electrodes,the field resistivity can be continuously observed.(4)Before irrigation and rainfall,there is a large high resistance area in the front and middle parts of the surface and profile of the loess.After irrigation,with the increase of soil moisture content,the high resistance area decreases in large area.After irrigation and rainfall,the overall resistivity of the soil is higher in the upper part and lower part,and irrigation has a greater impact on the change of soil moisture than rainfall.