Study On Electrical Resistivity Characteristics Of Dispersive Soil

Dispersive soil is one of the special soils,which has attracted much attention in Geotechnical engineering area in recent years,and it has low ability of erosion resistance and result in engineering damage easily.In view of the traditional judgment of dispersive soil test method is tedious,the results are often contradictory and have other shortcomings.This thesis based on soil mechanics,soil electrical,soil physics,soil chemistry and other theoretical knowledge.The TH2827 C precision LCR meter,pinhole test equipment,crumb test equipment,unconfined compressive strength test device and electron microscope scanning equipment had been investigated in different factors such as temperature,water content,porosity,the degree of saturation,quick lime content and curing age,so as to study their influence on dispersity,electrical resistivity,unconfined compressive strength and microstructure of soil.The main conclusions are as follows:(1)The electrical resistivity of non-dispersive clay and dispersive clay decreased in inverse proportional function relationship with the increase of temperature.The electrical resistivity of non-dispersive clay was significantly higher than dispersive clay with the same temperature,especially under the condition of low temperature(T< 10?).The electrical resistivity of clay could be taken as a basis for discriminating the dispersivity of clay.The resistivity decreased in power function relationship with the increase of water content and the degree of saturation,and increased in power function or linear function with the increase of porosity,but the change degrees were different.The reasons for the different resistivity characteristics of non-dispersive soils and dispersive soils had been analyzed,which mainly includes the dispersion mechanism,clay content and structural characteristics of dispersive soil.(2)With the increase of analytically pure quick lime content and curing age,the dispersity of soil decreased gradually and vanished finally.However,electrical resistivity of soil increased with the increase of analytically pure quick lime content but decreased with the extension of curing age.When the curing ages were uniform,the relationship between the unconfined compressive strength and electrical resistivity of modified soil was a positive linear correlation.And an electrical resistivity model of the dispersive soil modified with quick lime were established.(3)The analysis of scanning electron microscopy showed that,with the increase of the quick lime content and curing age,the particles of modified soil tended to be rounded from the flaky shape,and soil aggregates gradually became larger.The contacts between the soil skeleton units were from point-to-point contact and surface-to-surface contact to only surface-to-surface contact overhead pores in the skeleton of soils were gradually reduced,flocculus among the particles increased,and particle boundary became blurred,and contact areas were gradually increased,so that the interparticle junction was enhanced.In the view of macroscopic,the soils' water stability increased,the dispersive soil turned into non-dispersive soil and the electrical resistivity also changed.(4)Based on the quick lime modification mechanism and the soil's ternary conductive model of Mitchell,the reason for the change of electrical resistivity characteristics of dispersive soil modified with quick lime had been explained from the microstructure angle.