冻融循环作用下水泥改良土的力学性质研究  

Research on the Mechanical Properties of the Cement-Modified Soil under the Action of Freezing and Thawing Cycles

作　　者：王天亮[1,2] 刘建坤[1] 彭丽云[1] 田亚护[1] 

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]石家庄铁道大学土木工程学院,河北石家庄050043

出　　处：《中国铁道科学》2010年第6期7-13,共7页China Railway Science

基　　金：国家自然科学基金资助项目(50678020);铁道部科技研究开发计划项目(2006C011-B-2);北京交通大学校科技基金资助项目(2008RC041)

摘　　要：针对季节性冻土区的特殊环境,对冻融循环后的水泥改良土进行系列动静试验,研究土体的物理性状、力学特性与冻融次数、冷冻温度的关系。结果表明,反复冻融作用改变了土体的性状,这一改变过程是使土体内部结构从不稳定态向动态稳定平衡状态发展的过程;其应力—应变关系呈应变软化型,表现为脆性破坏,存在明显的剪切面;动荷载作用下,水泥改良土试样存在一临界状态,其破坏过程分为3个阶段:微裂纹出现、裂纹扩展和整体错动;经历3次冻融作用后,其临界动应力随冻融次数下降趋势变缓;动应力和冻融作用对水泥改良土的回弹应变影响显著;回弹模量存在一临界值,其值随冷冻温度的降低而降低。According to the special environment existed in the seasonal permafrost areas,a series of dynamic and static tests on the cement-modified soil subjected to freezing and thawing cycles were conducted. The relationship between the physical properties,the mechanical characteristics and the number of freezing-thawing cycles,the cooling temperature was deeply researched.The results show that the repeated freezing-thawing action has changed the physical characteristics of the soil,which is a process of the development from an unstable state to a dynamical stable state.The stress-strain relationship of the cementmodified soil is work-softening.Cement-modified soil is mainly in a brittle failure and existing obvious shear plane.The cement-modified soil sample has a critical state under the dynamic load,and its failure process covers three stages,including the micro crack,crack propagation and shear plane.The tendency of the critical dynamic stress reducing rate becomes very slow after three freezing-thawing cycles.The dynamic stress and the freezing-thawing cycles have significantly affected the resilient strain of the cement soil.There is a critical value in the resilient modulus,which is going down with the cooling temperature.

关 键 词：路基 水泥改良土 冻融循环 动力特性 静力特性 

分 类 号：TU411.8[建筑科学—岩土工程] P642.16[建筑科学—土工工程]