摘要
为了探究冻融循环条件下水泥改良路基土的力学特性变化,设计正交试验方案进行相应冻融循环条件下的三轴压缩试验,得到强度影响因素的敏感性排序,找到最佳试样配合比,并引入破坏应变能密度的概念,从能量角度对宏观力学变化规律进行了探究。结果表明:不同试验条件下,水泥改良土经历1次冻融循环作用后强度降低明显,初始黏聚力最大降低49.4%;水泥改良土强度影响因素中龄期及压实度的敏感性较强;水泥改良土在不同围压下经历1次冻融循环,破坏应变能密度分别降低41.12%、38.84%、34.73%、37.80%;分析发现破坏应变能密度和宏观强度与冻融循环次数呈负相关,与围压呈正相关。
To explore the change of the mechanical properties of cement-improved subgrade soils under freeze-thaw cycles,laboratory mechanical tests were carried out to obtain the influencing factors of the strength of cement-improved soils and the range of the factors.Then an orthogonal test was designed to obtain the sensitivity ranking of each influencing factor.The optimal mixture ratio is used to explore the strength changes of the sample under the freeze-thaw cycles,and the concept of failure strain energy density was used to verify the law of macro-mechanical strength change from the energy point of view.The results show:the maximum dry density of the cement-improved soil decreases with the increase of cement content,and it is slightly less than the maximum dry density of undisturbed soil;The optimal moisture content increases with increasing of cement content;the selected factors affecting the strength of the cement-improved soil are curing age,compaction,cement content and moisture content;A variance and range analysis for the orthogonal test results shows that the strength is more sensitive to age and compactness;The best test plan is characterized as curing period 28 d,4%cement content,95%compaction,and 16%moisture content;After undergoing freeze-thaw cycles,the strength of cement-modified soils decreases significantly after the first freeze-thaw cycle,and the cohesion in the shear strength index decreases while the internal friction angle slightly fluctuates with the increase in the number of freeze-thaw cycles;After the first freeze-thaw cycle,the failure strain energy density decreases by 41.12%,38.84%,34.73%,37.80%under different confining pressures;Under the same freeze-thaw cycle,the failure strain energy density of the cement-modified soil increases with the increase of confining pressure;The failure strain energy density is negatively correlated with the number of freeze-thaw cycles,positive correlation with the confining pressure,and consistent with the macroscopic mechanical strength change law.
作者
崔宏环
张振寰
何静云
杨兴然
王伟浩
王小敬
CUI Hong-huan;ZHANG Zhen-huan;HE Jing-yun;YANG Xing-ran;WANG Wei-hao;WANG Xiao-jing(Hebei Innovation Center of Transportation Infrastructure in Cold Region,Hebei Institute of Construction Engineering,Zhangjiakou 075000,Hebei,China;Beiwang Construction Group Co.,Ltd.,Chengde 067000,Hebei,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2021年第5期1957-1963,共7页
Journal of Safety and Environment
基金
国家自然科学基金项目(51878242)
河北省教育厅重点项目(ZD2020325)
河北建筑工程学院校级创新基金项目(XB201916)
。
关键词
安全工程
破坏应变能密度
水泥改良土
冻融循环作用
正交试验
safety engineering
failure strain energy density
cement modified soil
freeze-thaw cycle
orthogonal test
