(1. Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources，Yangtze River Scientific
Research Institute，Wuhan，Hubei 430010，China；2. CCCC First Harbor Consultants Co.，Ltd.，Tianjin 300222，China)
Abstract：The mesoscopic numerical method for simulating unsaturated soil-rock mixture is presented based on its mesostructure features. This method includes the technique for generation of mesostructural model，master-slave contact surface algorithm，and seepage and strength theory of unsaturated soil. The feasibility and rationality of proposed method are validated by comparing the numerical results to the results obtained in laboratory experiments of unsaturated soil-rock mixture. The proposed method is then used to analyze the factors，such as the contact behaviours of soil-rock interface，rock block content and saturation degree，and their influences on the mechanical characteristics and failure mechanism of unsaturated soil-rock mixture. It is found that：(1) Under low confining pressure，unsaturated soil-rock mixture exhibits remarkable shear dilatancy，which are influenced significantly by rock block content and degree of saturation at this time. Under high confining pressure，unsaturated soil-rock mixture exhibits shear contraction. As rock block content increases，the deformation of shear contraction decreases；and the influence of saturation degree is small. (2) The peak strength and deformation modulus of soil-rock mixture increase nonlinearly as the friction coefficient of soil-rock interface increases. When friction coefficient is above 0.6，values of peak strength and deformation modulus tend to be stable. (3) The increase of rock block content will lead to the increases of peak strength and deformation modulus of unsaturated soil-rock mixture. Strain-hardening feature at this time becomes more remarkable. When rock block content exceeds 58%，values of peak strength and deformation modulus tend to be stable. Under low confining pressure，the increase of rock block content will lead to the increase of shear dilatancy deformation. Under high confining pressure，the increase of rock block content will lead to the decrease of shear contraction deformation. (4) The increase of saturation degree will lead to the decrease of matric suction and peak strength of soil-rock mixture but have little influence on deformation modulus.
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2012, Vol. 31 
