摘要
黄土是一种典型的非饱和土,在总结前人试验研究的基础上,以甘肃省永靖县黑方台非饱和黄土为研究对象,进行两种不同的直剪试验,即:利用改进后的非饱和直剪仪对研究区不扰动黄土进行控制基质吸力和净竖向压力为常数的固结慢剪试验,依据研究区土水特征曲线配置不同含水率以控制不同的基质吸力的黄土快速直剪试验。得到两种试验方法下不同基质吸力或含水率和净竖向压力下的非饱和黄土抗剪强度及其参数,探讨非饱和黄土抗剪强度及其参数与基质吸力的关系,并分析两种试验方法所得非饱和黄土抗剪强度及其参数的差异。试验结果表明:两种不同的试验方法下净竖向压力及基质吸力对于研究区非饱和黄土抗剪强度均呈线性增长关系,而抗剪强度参数—黏聚力与基质吸力二者呈线性关系,内摩擦角—基质吸力关系曲线近似成水平直线,其中不同含水率黄土直剪试验在相同基质吸力和竖向压力的条件下,其抗剪强度及内摩擦角略高于非饱和固结排水直剪试验,而其黏聚力略低于非饱和固结排水直剪试验所得黏聚力。
Loess is one kind of typical unsaturated soil.Based on the previous test results,we carried out two different direct shear tests by taking unsaturated loess of Heifangtai platforrm at Yongjing,Gansu province as the study object.One is the consolidated slow-shear test of controlling matric suction and vertical pressure on undisturbed loess in the study area by using improved unsaturated direct shear apparatus,and the other is loess fast direct shear test based on the SWCC configured with different moisture content to control different matric suction.As a result,the shear strength of unsaturated loess and its parameters under different matric suction or water content and net vertical pressure under the two different test methods are obtained.Moreover,the relationship between the shear strength of unsaturated loess and its parameters and matrix suction is discussed,and the differences of shear strength of unsaturated loess and its parameters obtained by two test methods are analyzed.All these provide a theoritical support for future control of loess landslides.The test results show,the net vertical pressure and the matrix suction under the two different test methods have a linear growth relationship with the shear strength of unsaturated loess in the study area.There is a linear relationship between cohesive force and matrix suction.The relationship curve between the internal friction angle and the matrix suction shows approximately a horizontal line.Under the condition of the same matrix suction and vertical pressure,the shear strength and the internal friction angle in the direct shear test of the loess with different water content are slightly higher than those in unsaturated consolidated drainage direct shear test,while the cohesive force from the former test is slightly lower than that of the latter.
作者
郭倩怡
谷天峰
谢婉丽
吴熠哲
Guo Qianyi;Gu Tianfeng;Xie Wanli;Wu Yizhe(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069,China)
出处
《防灾科技学院学报》
2018年第1期25-31,共7页
Journal of Institute of Disaster Prevention
基金
国家自然科学基金重点项目(41630639)
西北大学研究生创新人才培养项目(YZZ15017)
关键词
非饱和黄土
抗剪强度
基质吸力
unsaturated loess
shear strength
matric suction
