膨胀土与改性膨胀土的动力特性试验研究

在成都绕城路膨胀土路基改性试验研究的基础上,利用动三轴试验研究膨胀土及改性膨胀土在重复荷载作用下的永久变形及动力特性。分析了不同围压下弹性应变、累积塑性应变和动应变与荷载重复作用次数之间的关系,在双对数坐标系中比在普通坐标系中能更好地区分累积塑性应变的3个阶段。当忽略第1和3阶段时,累积塑性应变与荷载作用次数之间在双对数坐标系中近似呈线性关系。膨胀土的动应变与荷载作用次数之间也有类似的关系。比较了膨胀土与改性膨胀土的动力特性(如动弹性模量、动粘聚力、动摩擦角、阻尼比等),表明经改性后膨胀土的力学特性得到了明显增强。

TESTING STUDY ON DYNAMIC PROPERTIES OF EXPANSIVE SOIL AND IMPROVED EXPANSIVE SOIL

Based on the improving tests of expansive soil roadbed of Chengdu Bypass Expressway,permanent deformation and dynamic properties of expansive soil and improved expansive soil under repeated loading are studied using dynamic triaxial test. Under the different confining pressures,the relationships among elastic strain, cumulative plastic strain,dynamic strain and the number of loading repetition are analyzed respectively. The three stages of cumulative plastic strain of expansive soil are easier to distinguish from log-log coordinate system than from common coordinate system. The log-log relationship between the cumulative plastic strain and the number of loading repetition is approximately linear when ignore the primary stage and the tertiary stage of material deformation. There is similar relationship between dynamic strain of expansive soil and the number of loading repetition. The dynamic properties,such as dynamic elastic modulus,dynamic cohesion,dynamic friction angle, damping ratio,of expansive soil and improved expansive soil are compared. The results show that the engineering characteristics and strength parameters of improved expansive soil are significantly improved.