高边坡开挖应力路径下黄土变形和强度特性的试验研究

EXPERIMENTAL STUDY OF DEFORMATION AND STRENGTH PROPERTIES OF LOESS UNDER THE EXCAVATION STRESS PASS OF HIGH SLOPES

为了探究高边坡开挖路径下黄土的力学性质,首先采用线弹性有限元法模拟一高150m的人工边坡在开挖条件下,潜在破坏区黄土的应力路径。据此路径分别对天然和饱和试样做了三轴固结不排水试验,并做了相同固结应力的加载应力路径试验(CTC)。结果表明开挖应力路径下饱和试样的应力应变关系为应变软化,天然试样为应变硬化;CTC试验条件下,饱和试样应力应变也为应变软化,天然试样亦为应变硬化,但硬化比开挖应力路径明显。上述两种试验条件下,饱和试样的有效应力路径接近,强度包络线相同,有效强度参数相同;天然试样则不同,强度包络线近似平行,开挖应力路径下有效黏聚力c'高于CTC,有效内摩擦角φ'相差不大。实际工程中获取土体变形和强度性质时应考虑应力路径和含水率的影响。

To explore the mechanical behavior of loess under excavation of high slopes,the linear finite element method was first utilized to obtain the stress paths of loess on the potential failure zone of an artificial high slope of150 m in Huanneng Country,Huan Town,Qingyang City,Gansu Province. Based on the stress path above,undrained triaxial tests were then performed on soils with natural and saturate water content. By comparison,conventional loading stress path tests（ CTC） with the consolidation stress identical with the tests above were also performed. Results show that under the excavation condition,the stress-strain curves of saturate loess are strainsoften and those of soil with natural water content are slightly strain-harden. Under the conventional loading condition,the stress-strain curves of saturate samples have the same characteristic with the tests above. While the natural water content samples display great strain- harden characteristics. In the two types of tests,the effective stress paths,strength envelope and the effective strength parameters are almost the same for the saturate samples.But for the loess with natural water content,the strength envelops are paralleled with the effective internal frictionangle almost the same and the higher cohesion for the stress path tests.