膨胀土膨胀模型及边坡工程应用研究

膨胀土吸湿膨胀往往会导致工程安全问题。以南阳中膨胀土为研究对象，通过改良试样进水控制系统、测量外体变等措施，实现三轴应力状态膨胀试验，研究充分吸湿引起的体积膨胀率、终了含水率与初始含水率、平均主应力之间的规律关系。试验发现：三轴应力状态下的体积膨胀率与终了含水率均随平均主应力的增大而减小，且在半对数坐标中均呈较好的线性关系，据此建立了三轴应力状态的膨胀模型。将该膨胀模型应用到数值计算中，分析了考虑膨胀变形对膨胀土边坡应力场分布的影响规律，比较了充分吸湿条件下不同膨胀等级的膨胀土边坡的塑性区发展特征，并针对不同厚度换填处理措施进行了效果验证。研究表明：该膨胀模型表达式简洁，参数求取简单，用于数值计算成果合理可靠，具有较强的实用性。

Expansion model of expansive soil and its application to slope engineering

Swelling deformation of expansive soil due to moisture absorption often leads to safety problems of engineering. Taking Nanyang mid-expansive soil as research object, the triaxial expansive experiment has been realized by improving the water inlet control system and the measurement of external volumetric strain. And the relationship between the volume expansion rate after sufficient moisture absorption, the final water content and the initial water content, the average principal stress has been obtained through the triaxial expansive test. Experimental results show that the volume expansion rate and final water content in different stress states decrease while the cover load or the average principal stress increases, which has a good linear relationship in semi-logarithmic coordinates. Through theoretical derivation, the unified relationship and expression of expansion models in different stress states are established. And applying the expansion model in the numerical calculation, law of stress field distribution of expansive soil slope considering swelling deformation is analyzed; plastic zone developing character of expansive soil slope with different expansion grades in the condition of sufficient moisture absorption is compared; effect of replacement measures with different treatment thicknesses is proved. Operation of this expansive experiment is simple, and the expression of this model is relatively concise, whose parameters are easily obtained. This model can be used in numerical calculation and simplified calculation, which has good practical value.