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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。
When the moisture content changes, the volume of expansive soil will produce water-swelling or water-shrinkage, which is similar to the reaction of the general materials when the temperature changes. When the expansion and contraction of soil deformation constraints will produce stress, thus put forward the concept of wetting stress. Based on the theory of elastic mechanics and using the theory of elasticity, the deformation and deformation of soils are calculated by using the wetting stress, and a theoretical model of calculating the wetting stress by the change of water content is established. It is revealed that the mechanism of fissure generation is the difference of soil moisture loss rate at different burial depths, resulting in nonuniform shrinkage deformation. The critical wetting criterion of initial cracking of expansive soil is proposed, which is consistent with the measured results. Using this model, the initial development depth of the expansive soil under the condition of surface evaporation is deduced. The relationship between the deformation modulus and the expansion and contraction parameters of the soil is also discussed.