高吸力下高庙子钙基膨润土的土水–力学特性

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

高庙子钙基膨润：已具有明显的湿胀干缩特性，吸力变化会引起持水状态和孔隙比的变化。用蒸汽平衡法测得高吸力段（3-287MPa）高庙子钙基膨润士的士水特性和变形特性。分析比较了吸力路径、试样初始孔隙比、应力加载历史以及土体结构对土水特性、变形及吸力应力的影响。研究表明，脱湿和吸湿过程中孔隙比的差异会引起体积含水率和饱和度的滞回。饱和度与吸力间关系受试样初始孔隙比和孔隙结构影响较大，与应力加载历史无商接关系。由吸力引起的吸力应力随吸力的增大而非线性增大，并在较高吸力时趋向于一定值。吸力应力受吸力路径、初始孔隙比以及孔隙结构的影响。

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 （34287 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.