不排水条件下轴向加卸载时结构性土的力学特性探讨  

Investigation on mechanical properties of structured soils subjected to axially loading-unloading under undrained conditions

作　　者：何淼[1,2] 刘恩龙[1,2] 陈亚军 唐勇[1,2] 

机构地区：[1]四川大学水力学与山区河流开发保护国家重点实验室,四川成都610065 [2]四川大学水利水电学院,四川成都610065 [3]中国电建集团昆明勘测设计研究院有限公司,云南昆明650000

出　　处：《岩石力学与工程学报》2017年第2期466-474,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51009103)~~

摘　　要：为研究结构性土在不排水条件下的力学特性,开展固结不排水条件下初始应力各向异性结构性土、各向同性结构性土及重塑土在25,50,100,200及400 k Pa共5种围压下的三轴加卸载试验,并利用二元介质概念对试验现象进行了分析。结果表明:结构性土在固结应力较低时结构性保持较好,存在明显的结构屈服强度,不同应力循环中平均模量无明显变化;固结应力较高时结构性减弱,表现为与重塑土相似的特性,受结构性减弱及正孔压等因素影响,平均模量随εa增加而减小;结构性土胶结元破损率与摩擦元中土颗粒间距随轴向应变增加而增大,卸载时体缩趋于明显。To study the mechanical properties of structured soils under undrained conditions,the triaxial compression tests on reconstituted soils and two kinds of structured soils with initial stress-induced anisotropy and isotropy were carried out under axially loading-unloading-reloading. The soils were tested under consolidationundrained（CU） conditions at the confining pressures of 25,50,100,200 and 400 k Pa,and the results of tests are analyzed with the binary-medium theory. It is found that the structured soils have stronger structures at lower consolidation stress. Meanwhile,Eave does not change significantly in different stress cycles. When the confining pressures are higher,the structures of soils are weakened,and their characteristics are similar to those of reconstituted soils. Because of the structure weakening and positive pore pressure,Eave decreases with the increase of εa. With the increase of the axial strain,the breakage rate of the bonded components and the soil particle spacing of friction components increase. In the meantime,the tendency of the volume contraction becomes more apparent when unloading.

关 键 词：土力学 结构性土 固结不排水条件 轴向加卸载试验 力学特性 

分 类 号：TU411[建筑科学—岩土工程]