摘要
为研究冰川泥石流物源区松散堆积体的剪切破坏行为及其剪切强度特性,选取帕隆藏布流域3条泥石流沟道内的冰碛土作为主要研究对象,进行室内常规三轴饱和状态下不排水剪切试验,获得冰碛土在不同应力状态下的剪切变形特征、孔隙水压力变化以及强度特性,分析不同泥石流沟内冰碛土孔隙水压力对土体破坏的作用机制.结果表明,冰碛土的应力-应变关系表现为应变软化型,呈脆性破坏特征,在较小轴向应变(<2%)下可达峰值强度;孔隙水压力与轴向应变增长到峰值后趋于稳定,两者呈无明显峰值点的非线性关系曲线;总应力路径近似直线,有效应力路径曲线在总应力路径的左侧,剪切过程中产生正孔隙水压力;有效固结围压增加,变形模量、峰值强度及其对应的轴向应变随之提高;孔隙水压力变化可间接反映土体剪切力学行为,但易受岩性、应力状态等因素影响.
The aim of this study is to fundamentally examine the undrained shear behavior for moraine soil, which was taken from the source areas of three debris flows in the Parlung Zangbo Basin. A series of conventional triaxial tests in a larger scale were used to detect the properties of moraine soils under differing effective confining pressures. Based on this, the mechanism of pore water pressure of moraine soil in three debris flow gullies on soil damage was further analyzed. The results showed that the stress-strain curves were featured by strain-softening and peak shear strength could be reached under a small axial strain(<2%), which indicated that the moraine soils failed by the brittle character. The relationship between the pore-water pressure and axial strain depicted the nonlinear characteristic as well, where the pore-water pressure gradually increased to the peak value and kept to a critical state during shearing. The total stress path curves showed an approximately straight line, whereas the effective stress path curve nonlinearly turned to the left due to the generation of a positive pore-water pressure during shearing. The parameters of the deformation modulus, peak shear strength and its corresponding strain were used to evaluate the shear strength properties, and these parameters increased with the effective consolidation confining pressure. The variation of pore water pressure indirectly reflected different shear mechanical behaviors, and the soil shear strength would be affected by mineral compositions of moraine soils.
作者
付宴菊
江耀
王姣
FU Yan-ju;JIANG Yao;WANG Jiao(Key Laboratory of Mountain Hazards and Surface Process,Chinese Academy of Sciences,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China;University of Chinese Academy of Sciences,Beijing 100049,China;Center for Excellence in Tibetan Plateau Earth Sciences,Chinese Academy of Sciences,Beijing 100101,China)
出处
《兰州大学学报（自然科学版）》
CAS
CSCD
北大核心
2021年第2期200-206,共7页
Journal of Lanzhou University(Natural Sciences)
基金
中国科学院前沿科学重点研究项目(QYZDY-SSW-DQC006)
中国科学院率先行动“百人计划”
国际自然基金委国际(地区)合作与交流项目(41520104002)
国家自然科学基金青年项目(41807278)。
关键词
三轴试验
冰碛土
剪切行为
孔隙水压力
强度特性
triaxial test
glacial till
shear behavior
pore-water pressure
strength property
