中文摘要：

含水率变化时膨胀土体积会产生吸水膨胀或失水收缩,这与温度变化时一般材料的反应相似。当土体的胀缩变形受到约束时就会产生应力,据此提出了变湿应力的概念。借用温度应力理论分析思路,基于弹性力学理论,采用变湿应力来计算土体的胀缩变形,建立了用含水率变化计算变湿应力的理论模型。揭示了裂隙产生的机理是不同埋深处土体水分丧失速率的不同,产生了不均匀的收缩变形。提出了膨胀土初始开裂的临界变湿判据,经比较与实测结果较一致。利用该模型,推导了地表蒸发条件下膨胀土的裂隙初始开展深度,并对其与土体变形模量、胀缩特征参数等的关系进行了讨论。

英文摘要：

Water swelling and drying shrinkage due to moisture change is the expansive soil＇s characteristic which is similar to the thermal effect of material.Stress is generated by the swell-shrinking deformation constraints and the concept of moisture change stress is put forward.The moisture change stress is adopted to calculate swell-shrinking deformation based on the thermal stress and elasticity theory.A theoretical model which could calculate the moisture change stress resulted from moisture change is established.The mechanism of cracking is the different rates of water loss in different depths which caused the uneven shrinkage deformation.The critical value of moisture change for initial cracking is presented,which is consistent with measured result.The initial depth of expansive soil cracks is put forward by proposed model.The relationship between the depth of initial cracking and soil parameters such as deformation modulus,swell-shrinking characteristics,etc.are discussed in detail.