饱和黏性土异性固结三轴拉伸试验研究  

Experimental Study on Triaxial Extension Tests of Anisotropically Consolidated of Saturated Clay

作　　者：祝刘文[1] 代云霞[1] ZHU Liu-wen;DAI Yun-xia(Fourth Harbour Design and Investigation Engineering Company Limited,China Communications Construction Company,Guangzhou 510230,China)

机构地区：[1]中交第四航务工程勘察设计院有限公司,广州510230

出　　处：《武汉理工大学学报》2022年第10期87-92,101,共7页Journal of Wuhan University of Technology

摘　　要：通过应力控制式三轴仪对饱和黏性土进行了异性固结不排水拉伸和等向固结不排水压缩试验。结果表明:拉伸试验呈应变硬化破坏模式,试样首先发生轴向均匀伸长及径向收缩,随着应变局部化试样会产生一定颈缩而造成应力集中。拉伸过程中超孔隙水压力为负值,其绝对值随着应变的增大而增大,拉伸应力路径呈L型。异性固结不排水拉伸强度是等向固结不排水压缩强度的0.58倍,研究提出在无异性固结拉伸试验条件时,可通过常规等向固结不排水压缩试验换算拉伸强度。临界状态理论适用于异性固结三轴拉伸试验,临界孔隙比随平均主应力增大而减小,试样处于超固结状态时,其临界状态点高于拟合的临界状态线,进入正常固结状态后应力比趋于稳定,线性关系较好。A series of anisotropically consolidated undrained extension tests were carried out using the stress-controlled triaxial apparatus.The conventional isotropic consolidated undrained compression tests were performed simultaneously.The results show that the failure mode shows strain-hardening feature in extension test.The specimen firstly undergoes uniform axial extension and radial shrinkage during the test,when the strain localization is developed in the plane of weakness,however,the necking will result in concentration of stress.The excess pore water pressure is negative and its absolute increases with strain.The stress path of extension tests are letter L-type.The undrained extension strength of anisotropic is 0.58 of isotropic triaxial compression.It is concluded that the undrained extension strength of anisotropic can be calculated by isotropic consolidated compression result in the absence of extension tests.The critical state theory is applicable to triaxial extension test.The critical void ratio decreases with the increase of principal stress.The stress ratio shows a certain of nonlinearity when the sample is overconsolidated,and the critical state stress distribution is slightly higher than the fitted line.The stress ratio tends to be stable which satisfies a good linear relationship when the sample is normal consolidated.

关 键 词：异性固结 等向固结 三轴拉伸 不排水强度 临界孔隙比 临界应力比 

分 类 号：TU442[建筑科学—岩土工程]