深埋隧洞饱和原状Q_2黄土三轴剪切特性试验  

Test on triaxial shear properties of saturated undisturbed Q_2 loess in deep-buried tunnel

作　　者：江耀[1] 谌文武[1] 孙冠平[1] 刘小伟[1] 张帆宇[1] 

机构地区：[1]兰州大学土木工程与力学学院西部灾害与环境力学教育部重点实验室,兰州730000

出　　处：《兰州大学学报（自然科学版）》2012年第3期23-27,33,共6页Journal of Lanzhou University(Natural Sciences)

基　　金：国家科技支撑计划项目(2010BAK67B16-3)

摘　　要：为进一步探讨饱和原状Q2黄土在三轴应力状态下的变形，孔隙水压力变化以及强度特性，利用GDS多功能三轴仪，对甘肃引洮输水工程15#隧洞原状黄土进行了常规三轴不排水剪切试验．通过对试验数据的整理与分析发现：在常规三轴不排水剪切试验下，原状Q2黄土的应力一应变曲线呈应变软化型，表现为脆性破坏；随着围压的增大，曲线的软化性状减弱；在土的峰值强度出现前，变形几乎近似“弹性”．土在剪切过程中产生正孔隙水压力，曲线在低围压下具有峰值压力，变化似软化型；在高围压下孔隙水压力随着轴向应变的增加而增大．随着围压的增大，原状Q2黄土的破坏应力随之提高，有效应力路径曲线形态呈相似的直线形．With a GDS multifunctional triaxial apparatus, the conventional consolidated undrained triaxial shear tests were carried out to study the effects of deformation, changes of pore-water pressure and properties of strength of saturated undisturbed Q2 loess in the fifteenth tunnel of Yintao water transmission project in Gansu province. Based on scientific interpretation and analysis of test data, the stress-strain curve of saturated undisturbed Q2 loess under a conventional consolidated undrained triaxial shear test showed a strain softening, while the failure model displayed brittle failure. The softening behavior of the stress-strain curve had a trend of attenuation with the increase of confining pressure~ and the strain before the peak was approximately elastic. During the process of shear test, the pore-water pressure was positive. Under lower confining pressure, the pore- water pressure curve had peak value and the shape of pore-water pressure curve looked like softening. While the pore-water pressure under a larger confining pressure increased with an increasing axial strain. It was also shown that the strength of undisturbed Q2 loess would increase with the confining pressure and the breaking stress of loess would augment with it. The curve of the effective stress path had a similar linear shape.

关 键 词：土力学 Q2黄土 三轴剪切 应变软化 孔隙水压力 强度 

分 类 号：TU411.3[建筑科学—岩土工程]