摘要
为研究北京富水砂卵石地层冻结后的强度特性,以北京某地铁暗挖车站砂卵石为研究对象,进行不同温度(-5、-10、-15、-20℃),不同围压(0.0、0.3、0.8、1.3、2.0、3.0、4.0、8.0 MPa)条件下三轴压缩试验。试验结果表明:冻结砂卵石的应力-应变曲线以应变软化形态为主,高负温、高围压条件下,呈现理想塑性破坏形态;砂卵石强度、黏聚力和摩擦角均随温度降低而增大,其中强度呈指数分布,黏聚力和摩擦角呈线性分布;强度和弹性模量随围压增加而增大,但增大趋势逐渐减小,低围压压缩区强度满足线性Morh-Coulomb(简称M-C)准则;冻结砂卵石的破坏形态以破裂面始/终于试样侧面的剪切破坏为代表,张拉型破坏受冰影响显著,仅存在于低围压条件下,高围压、高负温时易出现体胀型破坏。
This paper investigates the strength characteristics of water-rich sandy gravel subjected to freezing, as this soil is often encountered in Beijing. A series of triaxial compression tests has been performed on sandy gravel samples obtained at mining station of Beijing Metro at different temperatures（-5℃,-10℃,-15℃,-20℃） and confining pressures（0.0、0.3、0.8、1.3、2.0、3.0、4.0 MPa and 8.0 MPa）.The results show that： the behavior of frozen sandy gravel is dominated by strain softening, and the ideal plastic failure mode occurs only when the soil experiences high negative temperature and confining pressure; the strength, cohesion and friction angle of the soil all increase with the decrease of temperature. The variation of strength with temperature satisfies an exponential distribution, while the changes in cohesion and friction angle follow a linear relationship; the strength and elastic modulus of frozen sandy gravel increase as the confining pressure increases, but the increasing rate descends gradually. The Mohr-Coulomb criterion can still be used effectively to characterize the soil’s compressive response at low confining pressure. The failure mode of frozen sandy gravel is represented by shear failure with diagonal fractures on the lateral sides of the specimen. Tensile failure occurs when the specimen is subjected to a low confining pressure, and it is influenced by the formation of ice significantly. The mechanism of volumetric inflation has been found when a high level of temperature and confining pressure is applied to the specimen.
作者
张晋勋
杨昊
单仁亮
隋顺猛
薛东朝
ZHANG Jin-xun;YANG Hao;SHAN Ren-liang;SUI Shun-meng;XUE Dong-chao(Postdoctoral Workstation,Beijing Urban Construction Group Co.Ltd,Beijing,100088,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Beijing,100083,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2018年第11期3993-4000,4016,共9页
Rock and Soil Mechanics
基金
北京市科学技术委员会资助项目(No.Z161100001116088)~~
关键词
冻土强度
冻结砂卵石
力学特性
三轴压缩试验
strength of frozen soil
frozen sandy gravel
mechanical properties
triaxial compression test
