重塑膨胀土非线性强度特性及一维固结浸水膨胀应力-应变关系

采用南水北调中线工程南阳膨胀土和新乡膨胀岩重塑试样，开展一系列干湿循环后的强度试验和一维固结后的有荷浸水膨胀试验。试验结果表明，(1) 膨胀土强度随竖向应力增加表现出明显的两阶段特性，低应力状态与高应力状态下的强度指标差别很大；(2) 同一上覆压力下，膨胀土的有荷膨胀率随着初始含水率的增大而线性减小，随着初始干密度的增大而线性增大，分别给出考虑初始含水率、上覆压力双因素影响的膨胀率表达式和考虑初始干密度、上覆压力双因素影响的膨胀率表达式，给出膨胀土一维固结后有荷浸水膨胀的应力-应变关系。分析认为，(1) 膨胀土边坡多发生浅层滑动，应测定低应力状态下的强度参数用于边坡稳定分析；(2) 膨胀土边坡浅层部分和坡脚的压实度不宜过高。

Nonlinear strength property of remolded expansive soil and its stress-strain relationship for soaking after one-dimensional consolidation

A series of laboratory tests was conducted for investigating the swelling deformation characteristics after one-dimensional consolidation under different vertical pressures and the nonlinear strength properties after dry-wet cycles for remolded expansive soil/rock specimens, which were derived from the field test section in Nanyang and Xinxiang, where the Middle Line of Water Transfer Project from South to North China passes. The test results indicate that: (1) With the increment of vertical pressure, the shear strength of expansive soil obviously has two stages characteristics, that is to say, there is great difference between the strength parameters under low stress state and those under high stress state. (2) Under the same vertical pressure, swelling ratio of expansive soil decreases linearly with increment of original water content; while increases linearly with increment of original dry density. Swelling ratio expressions which simultaneously reflect the influences of original water content and vertical pressure, and the influences of original dry density and vertical pressure as well are presented, respectively. Moreover, a stress-strain relationship for soaking after one-dimensional consolidation is also presented. On the base of analysis, some suggestions are provided for expansive soil slope: (1) There are often shallow slides for slope of expansive soil, so strength parameters under low stress state should be measured and applied to its slope stability analysis. (2) High compaction degree for the shallow area of slope and toe of slope is inappropriate.