Experimental Study On Influence Of Adsorbed Combined Water On Strength And Deformation Of High Liquid Limit Soil

The influence of adsorption combined water on the strength and deformation characteristics of high liquid limit soil has been a hot and difficult topic.In order to reveal the influence mechanism of adsorption combined water on the strength and deformation characteristics of high liquid limit soil and the change law of adsorption combined water form and content in high liquid limit soil under load.It is proved that the high liquid limit soil with high moisture content can be directly used as the filling of the lower embankment under the condition of reducing the compactness.In this paper,the high liquid limit soil of Hainan G360 National Highway and Hunan Hengyong Expressway is studied.Through a series of laboratory tests,the main results are as follows:(1)The soil samples were treated by different concentrations of salt solution.The cation in the salt solution reacted with the surface anion of the soil particles,and the combined water film became thinner,and the adsorption combined water content decreased,so as to control the initial adsorption combined water content of the soil samples.At the same time,the adsorption combined water content was determined by thermogravimetric analysis and volumetric flask method.It was found that with the increase of the concentration of the salt solution of the treated sample,the adsorption combined water content decreased,the strong combined water content was basically unchanged,and the temperature of the adsorption combined water began to desorb increased slightly.(2)The high liquid limit soil with the same initial moisture content and different initial adsorbed bound water content was configured by different concentrations of salt solution,and the compactness of the soil sample was reduced to 90%.The shear test and unconfined compressive strength test were carried out.The results show that the unconfined compressive strength,shear strength and cohesion of the specimens decrease with the decrease of the initial binding water content,while the internal friction angle increases slightly.(3)Through the consolidation test under static load and the permanent deformation test under dynamic load on the samples with different initial adsorbed bound water content,the research results show that with the decrease of the adsorbed bound water content in the sample,greater compression deformation will occur under static load,and greater permanent deformation will occur under dynamic load.The permanent deformation test under different deviatoric stress and confining pressure was carried out.The test results show that the high liquid limit soil with high water content and low pressure solidity can be used as the filling of the lower embankment,and the lower embankment may still be plastic stable under the most unfavorable conditions.(4)By comparing the plastic strain generated by the specimens under dynamic and static loads,it is found that the specimens under the same size of dynamic and static loads will have greater plastic deformation under dynamic loads.This is because the pores are compressed and free water is discharged under static loads,but the adsorbed bound water in the specimens will not be discharged,and the adsorbed bound water in the specimens will also be discharged under dynamic loads,resulting in greater plastic deformation of the specimens.