干湿循环条件下广西南宁地区原状膨胀土的工程特性

Engineering properties of original state expansive soil in Nanning of Guangxi under the influencing of wetting-drying cyclic process

以广西南宁地区膨胀土为研究对象,考虑干湿循环作用的影响,通过室内试验对膨胀土的膨胀变形和强度特性进行测试。在试验中利用大环刀样模拟干湿循环过程,再转制小环刀样进行膨胀率和直剪试验,改善了试样制备中的尺寸效应。试验结果表明:干湿循环过程可有效降低土体的抗剪强度,对于新开挖膨胀土边坡需即时防护,可考虑采用结构措施部分限制土体的膨胀变形,从而有效降低干湿循环过程中土体强度的衰减,达到维持边坡稳定的目的。室内试验结果可为相关边坡设计中计算参数的选取提供参考。

Considering the influence of wetting-drying cyclic process to the expansive soil in Nanning of Guangxi,the swelling deformation and strength characteristics of the expansive soil are studied by the method of laboratory test.In the course of preparing samples,the common cutting ring is replaced by a large one.Then,the common cutting ring is used in the swelling tests and direct shear tests,which improve the size effects in the sample preparation.The test results show that the shear strength may decrease largely after the wetting-drying cycles.The new-cut slope should be protected immediately,and the structure measures could be used to restrain the expansion deformation partly,which may prevent the decrease of the shear strength to keep the slope stability.The test results also may provide the reference for the parameter selection in slope design.