Hydro-mechanical behaviour of GMZ Ca-bentonite at high suctions

Gaomiaozi (GMZ) Ca-bentonite has obvious swelling and shrinkage characteristics. The change in suction can induce changes in water retention state and void ratio. Soil-water characteristics of GMZ Ca-bentonite at high suctions (3～287 MPa) are measured by the vapor equilibrium technique. The influential factors such as drying-wetting process, initial void ratio, stress loading history and pore structure are analyzed respectively on the soil-water characteristics and mechanical behaviour. The main conclusions are as follows: (1) the difference in void ratio during drying and wetting process can bring about hysteresis in volumetric water content and degree of saturation; (2) the relationship between degree of saturation and suction is mainly determined by the pore structure and void ratio, which has no direct relation with the experienced stress loading history; (3) the soil-water characteristic curve (SWCC) can reflect the deformation characteristics with suction. Moreover, the existence of suction in samples can produce suction stress. The suction stress increases nonlinearly with the increasing suction and reaches a certain value at higher suction; (4) the suction stress due to suction is affected by the factors such as suction path, initial void ratio and pore structure.