南阳膨胀土变形与强度特性的三轴试验研究

对南阳膨胀土做了4种应力路径的三轴试验，即控制吸力的各向同性压缩试验、控制净平均应力的收缩试验、控制净平均应力的膨胀试验、同时控制净室压力和吸力的排水剪切试验，结果表明：膨胀土各向同性压缩屈服特性仍可用一般非饱和土的LC屈服线描述；不同围压下的收缩路径的屈服吸力随围压增大而减小，且屈服后的收缩指数接近各向同性压缩屈服后的压缩指数；非饱和状态下的内摩擦角近似等于饱和状态下的有效内摩擦角，总粘聚力随吸力增加而线性增大；在各向同性压缩试验和三轴剪切试验过程中，土样含水量随净平均应力的变化都近似为线性关系。

STUDY ON DEFORMATION AND STRENGTH CHARACTERISTIC OF EXPANSIVE SOIL WITH TRIAXIAL TESTS

The triaxial tests of Nanyang unsaturated expansive soil are carried out under four kinds of stress paths, that is isotropic loading tests at various controlled suction, shrinkage tests at various controlled net mean stress, swelling tests at various controlled net mean stress and drained shear tests under controlled cell pressure and suction. Many meaningfull results are obtained. The yield behaviour under isotropic loading of expansive soil can be described by the LC curve, The yield suction of shrinkage test decreases as the net mean stress increasing. The friction angle under unsaturated state is close to that under saturated condition. The total cohesion increases with suction. The water content changes linearly with the net mean stress at isotropic loading test and triaxial shear test. The relationship between water content and suction is also linear under shrinkage test and swelling test.