基坑开挖卸荷路径下饱和粉土强度特性研究  

On Strength Characteristics of Saturated Silt under Excavation Unloading Path

作　　者：周游 刘孙祥 王益楠 沈楠杰 蒋刚 ZHOU You;LIU Sunxiang;WANG Yinan;SHEN Nanjie;JIANG Gang(Shanghai Tunnel Engineering Co.,Ltd.,Shanghai 200032,China;College of Transportation Engineering,Nanjing Tech University,Nanjing 210009,China)

机构地区：[1]上海隧道工程有限公司,上海200032 [2]南京工业大学交通运输工程学院,南京210009

出　　处：《路基工程》2024年第5期91-95,共5页Subgrade Engineering

摘　　要：结合南京市福建路地铁站基坑工程,开展饱和粉土的常规剪切和一系列不同应力比下K0固结排水剪切三轴试验,研究粉土在不同卸荷路径下的强度特性。结果表明:饱和粉土的应力-应变特性与应力路径密切相关,侧向卸荷及双向卸荷应力比小于1时为压缩破坏,轴向卸荷及双向卸荷应力比大于1时为拉伸破坏;偏应力增加的压缩破坏和偏应力减小的拉伸破坏临界状态线不相同;在坑底轴向卸荷区,常规三轴试验测得的内摩擦角显著偏大,会导致坑底被动土压力计算值偏于不安全。In relation to the foundation pit engineering of Fujian Road Metro Station in Nanjing,conventional shear test on saturated silt and a series of K0 consolidated-drained triaxial shear tests under different stress ratio were carried out to study the strength characteristics of silt under different unloading paths.The result shows that,the stress-strain characteristics of saturated silt relates to the stress path closely,when the stress ratio of lateral unloading to bidirectional unloading is less than 1,there presents compression failure,when the stress ratio of axial unloading to bidirectional unloading is larger than 1,there presents tensile failure;the compression failure with increased deviatoric stress,and the tensile failure with decreased deviatoric stress,have different critical state lines;in the axial unloading zone at the bottom,the internal friction angle measured by the conventional triaxial test is significantly larger,causing the calculation value of the passive earth pressure at the bottom to be of unsafety.

关 键 词：粉土 应力路径 K0固结 卸荷应力比 应力应变 

分 类 号：TU411.7[建筑科学—岩土工程]