The Research On The Swelling Deformation Law And Constitutive Relationship Of Expansive Soils In Ning-Ming

The dilational srtain of expansive soils is one of the most difficult problem in the field of engineering geology and unsaturated soils mechanics. At present,many tests on dilatationgal strain and research on swelling constitutive relationships have been carried out. However the overwhelming majority is based on plenteous water supply, and law drawn is all about wether the initial water content is constant, the single relationship between the swelling strains and vertical pressure,or when the vertical pressure is constant, the single relationship between the swelling strains and initial water content. The swelling mechanism of expansive soils is complicated ,to find out the major factor and to establish reasonable and accurate swelling constitutive relationship is the key to expansive soils. Based on the laboratory swelling experiments, relationship between the swelling strain under load and the vertical pressure,relationship between the swelling strain under load and initial water content ,relationship between the swelling strain under free load and initial water content and relationship between the swelling pressure and initial water content are systematically studied in this thesis,and put forward to a swelling prediction formula which can be used to calculate the swelling strain under load when the initial water content and the vertical pressure vary at the same time;the relationship between the final water content and initial water content ,the relationship between the final water content and vertical pressure is also presented, and bring forward a formula which can be used to calculate the final water content;additional, that the relationship between the swelling process strain under load and process water content is linear is also verified. Based on the laboratory swelling experiments results, the additional compression modulus,the initial tangent modulus in 1D ,deformation modulus and volume deformation modulus in 3D of expansive soils in Ning-Ming are formulated.