冻融作用下冻结黄土黏聚力长期强度变化规律  

Changing rule of long-term strength of frozen loess cohesion under impact of freeze-thaw cycle

作　　者：周泓[1,2,3] 张豫川[1,3] 张泽[2] 冯文杰[2] 周波[4] 武俊杰[2] 

机构地区：[1]兰州大学西部灾害与环境力学教育部重点实验室,兰州730000 [2]中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,兰州730000 [3]兰州大学土木工程与力学学院,甘肃兰州730000 [4]中国建筑材料工业地质勘查中心陕西总队,西安710003

出　　处：《岩土力学》2014年第8期2241-2246,2254,共7页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.41301070);中科院西部之光博士项目;教育部留学回国人员科研启动基金项目(第46批);青海省电力设计院自主立项课题(No.63-K2012-02)

摘　　要：以陕西富平重塑黄土为研究对象,使土样在封闭系统下经历不同次数的冻融循环作用,分析不同次数的冻融循环作用下土体黏聚力的变化规律。试验利用球形模板压入试验测定冻结黄土的相对瞬时强度和长期强度,结果表明,第4次冻融循环后冻结黄土的相对瞬时强度最大,之后在第6次大幅度降低,第8次又大幅度增加,但小于第4次,第10次之后逐渐趋于稳定。冻结黄土的长期强度在冻融循环第8次时最大,第6次和10次强度相近,处于中间水平,第4、50、100次时强度最低。相对瞬时强度的变化和其孔隙比、密度的变化整体上是相互对应的,这种变化规律与冻融过程中的水分迁移有着密切的关系。长期强度与物理性质的关系并不明显,它是土样内部结构、矿物成分以及物理性质的综合反映。Taking Shaanxi Fuping remolded loess as the object of study, soil samples gone through different numbers of freeze-thaw cycle under a closed system, and variations about mechanical index （cohesion） of soil at the different numbers of freeze-thaw cycle are analyzed. Experiment used spherical template into the determination of relative instantaneous strength and long-term strength of frozen loess. After 4 times, the relative instantaneous strength is the largest, but greatly reduces after 6 times. The relative instantaneous strength significantly increases at the eighth time （but less than the forth time）, and gradually becomes stable after 10 times. The largest long-term strength of frozen loess is at the eighth time. The long-term strength at the 6th time and 10th time is similar in the middle level. The lowest relative instantaneous strength is at the 4 th, 50 th and 100 th time. Void ratio and density changes are corresponding to relative instantaneous strength. This kind of change rule has the close relationship with moisture migration in the process of freeze-thaw. The relationship between long-term strength and physical properties is not obvious. It is a synthetical reflection of the internal structure, mineral composition and physical properties.

关 键 词：冻融循环 黏聚力 相对瞬时强度 长期强度 

分 类 号：TU4[建筑科学—土工工程]