Soil-water Properties And Prediction Of Unsaturated Permeability Coefficient Of Wide-graded Gravel Soi

Unsaturated soil exists in many geological disasters.The water phase,solid phase and gas phase in the soil are constantly changing in the process of rainfall.The change of unsaturated properties of soil also leads to the change of unsaturated strength,which finally affects the occurrence of geological disasters.Gravel soil,as a special soil,has the characteristics of wide range of particle size,large pores and small clay content,which is different from other soils.The unsaturated characteristics of gravel soil are also different from other soils.Therefore,the indoor soil-water characteristic experiments of wide-graded gravel soil are carried out in this paper,and the effect of porosity on the soil-water characteristic curve of wide-graded gravel soil is studied.Based on different soil-water characteristic curve models,the effect of porosity on unsaturated permeability coefficient is studied.Major progress has been made as follows:1.The physical properties of wide-graded gravel soil are carried out,and the specific gravity of wide-graded gravel soil and the range of water content under different porosity are obtained.2.78 groups of soil-water characteristic curves under four porosities were carried out,and the trend of matrix suction with water content under different porosity was obtained.The measured matrix suction increased gradually with the decrease of soil porosity under the same volume water content.3.Different soil-water characteristic curve models are obtained by fitting the experimental data.The expressions of soil-water characteristic curves with different porosity predicted by different models are obtained by establishing the relationship between different model parameters and porosity.Based on the verification experiment,the prediction results under different models are compared.The theoretical value of matrix suction calculated by the soil-water characteristic curve prediction formula based on G model is closer to the experimental value.Therefore,the G model can better describe the soil-water characteristic relationship of wide gravel soil.4.Based on the soil-water characteristic curve prediction formula established by G model,the unsaturated permeability coefficients of Jiangjiagou gravel soil,which is similar to the wide graded gravel soil gravel soil in this paper,are predicted by CCG model and Gardner model.The results show that the unsaturated permeability coefficient predicted by CCG model is closer to the experimental value.Therefore,based on the CCG model and the prediction formula of soil-water characteristic curve,the variation law of unsaturated permeability coefficient of wide graded gravel soil with different porosity is obtained.