膨胀土与结构物接触面的力学特性试验研究

桩周土的性质是影响桩侧摩阻力最直接的决定因素。膨胀土具有吸水软化的特性,膨胀土中桩侧摩阻力的发挥受膨胀土性质的影响很大。通过改进的直剪仪,对12种不同含水量、不同干密度的膨胀土与混凝土块接触面进行直剪试验,研究膨胀土性质对接触面特性的影响。结果表明:膨胀土与混凝土块接触面的剪切曲线均呈加工软化型,其峰值剪应力、残余剪应力符合Mohr-Coulomb准则,因此可将膨胀土与结构物接触面的剪切曲线简化为三折线曲线;接触面切向刚度系数不随垂直压力而变化,但与膨胀土的性质有关,随干密度的增加而增大,随含水量的增加而减小;接触面的强度指标也随干密度的增加而增大,随含水量的增加而降低。

Experimental Study on the Mechanical Characteristics of the Interface between Expansive Soil and Structure

The property of pile-side soil is the most direct determinant affecting the friction resistance to it,which is deeply influenced by the property of expansive soil to be softened upon absorbing water.This paper,by means of the improved direct shear apparatus,conducts the shear tests on 12 expansive soil-concrete interfaces,in which water content and dry density of the expansive soil are various.Results show that the shear curves of expansive soil-concrete interface display work softening type and both the ultimate shear stress and the residual shear stress accord with Mohr-Coulomb criterion.Therefore,the tangential curves of the interface between expansive soil and structure can be simplified as three-broken-line curves.The tangential stiffness coefficient of the interface is irrelevant to vertical stress,but relevant to the property of expansive soil.It increases with the increase of dry density and decreases with the increase,which is the same with the change in interface strength indices.