冻融循环作用下西藏东南冰碛土剪切力学特性试验研究  

Experimental Study on Shear Mechanical Properties of Moraine Soil in Southeast Tibet Subjected to Freeze-thaw Cycles

作　　者：邱恩喜 何巧玲 孙希望[3] 路建国 张蕊 万旭升[1] 渠孟飞 QIU Enxi;HE Qiaoling;SUN Xiwang;LU Jianguo;ZHANG Rui;WAN Xusheng;QU mengfei(School of Civil Engineering and Geomatics,Southwest Petroleum University,Chengdu 610500,China;State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(SKLGP),Chengdu 610059,China;China Railway Eryuan Engineering Group Co.,Ltd.,Chengdu 610031,China)

机构地区：[1]西南石油大学土木工程与测绘学院,四川成都610500 [2]地质灾害防治与地质环境保护国家重点实验室,四川成都610059 [3]中铁二院工程集团有限责任公司,四川成都610031

出　　处：《防灾减灾工程学报》2022年第6期1267-1279,共13页Journal of Disaster Prevention and Mitigation Engineering

基　　金：地质灾害防治与地质环境保护国家重点实验室开放基金(SKLGP2021K017);四川省高校工程研究中心开放课题(SC-FBHT2022-07);四川省科技厅项目(2020YJ0416);国家自然科学基金(42071087)资助。

摘　　要：西藏东南地区冰碛土堆积体广泛分布,冻融作用严重影响冰碛土堆积体稳定性。对西藏东南及川滇地区200组冰碛土粒径级配进行对比分析,并通过室内直剪试验研究了不同含水量和冻融循环作用下冰碛土剪切力学特性,结合试样体积变化及水分迁移规律分析黏聚力劣化机制。结果表明:(1)冰碛土粒径范围较广,相比川滇地区,西藏东南冰碛土细粒含量更多;(2)冻融循环后,黏聚力c呈负指数型函数降低,内摩擦角φ波动幅度-6.47%~+5.46%;(3)含水量越高、冻融循环次数越多、垂直应力越大的试样剪胀性越弱,剪缩性越强;冻融循环条件下,含水量越高的试样剪切带厚度变化范围越大;(4)冻融6次后,冰碛土体积无显著增长,水分迁移呈规律性,与黏聚力在冻融6次后劣化减缓相一致。Moraine soil accumulations are widely distributed in Southeast Tibet,and freeze-thaw cycles seriously affect the stability of moraine soil accumulations.In this research,the particle size distributions of 200 groups of moraine soils in southeast Tibet and Sichuan-Yunnan regions were compared and analyzed.The shear mechanical properties and deformation characteristics of moraine soil with different freeze-thaw cycles and moisture contents were carried out through the indoor direct shear test.The deterioration mechanism of cohesion was analyzed in combination with the change in sample volume and water migration.Results show that:(1)Moraine soil has a wide range of particle sizes.Compared with that in Sichuan-Yunnan region,the moraine soil in southeast Tibet has more fine particles.(2)After freeze-thaw cycles,the cohesion decreases as a negative exponential function,and the internal friction angle fluctuates from -6.47%~+5.46%.(3)The specimen with higher moisture content,more freeze-thaw cycles and greater vertical stress has weaker dilatancy and stronger shear shrinkage.Under the condition of freeze-thaw cycles,the variation range of shear band thickness increases with the increase of moisture content.(4)After 6 cycles of freezing and thawing,the volume of moraine soil does not increase significantly,and the water migration shows a regular pattern,which is consistent with the deterioration of cohesion after 6 cycles of freezing and thawing.

关 键 词：冰碛土 冻融循环 剪切特性 剪胀性 剪切带 黏聚力劣化 

分 类 号：TU43[建筑科学—岩土工程]