浸水作用下重载铁路基床动回弹模量衰减规律  

Attenuation Law of Dynamic Resilient Modulus of Subgrade Bed for Heavy Haul Railway under Water Immersion

作　　者：冯怀平[1] 宋慧来 常建梅[1] 魏亚辉 FENG Huaiping;SONG Huilai;CHANG Jianmei;WEI Yahui(State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University,Shijiazhuang Hebei 050043,China;Engineering Management Center,China State Railway Group Co.,Ltd.,Beijing 100844,China)

机构地区：[1]石家庄铁道大学省部共建交通工程结构力学行为与系统安全国家重点实验室,河北石家庄050043 [2]中国国家铁路集团有限公司工程管理中心,北京100844

出　　处：《中国铁道科学》2020年第3期21-30,共10页China Railway Science

基　　金：国家自然科学基金资助项目(51478279);河北自然科学基金项目(E2019210137)。

摘　　要：以包神铁路某病害段土体为研究对象,制备不同压实系数、不同含水率的试样,利用GDS动三轴系统进行模拟浸水状态下的动力特性试验;使用自行研制的常水头马氏瓶模拟雨水自然浸入基床,构建动力湿化环境,研究浸水作用下重载铁路基床动回弹模量衰减规律及敏感影响因素。结果表明:浸水过程会打破土体的动力稳定状态,引发塑性应变的持续累积以及动回弹模量的持续衰减,累积程度和衰减规律受到压实系数的显著影响;压实系数为0.96的土体在浸水作用下循环加载至50000次时其累积塑性应变小于3%,而压实系数分别为0.9和0.93土体的累积塑性应变皆大于10%;压实系数越大的土体在浸水作用下动回弹模量衰减程度越大,压实系数分别为0.9,0.93和0.96的土体在浸水作用下其动回弹模量分别衰减22%,32%和42%;不同初始含水率土体的累积塑性应变和动回弹模量衰减规律相近。在试验数据基础上,提出了用动回弹模量构建的动力湿化作用下的土体软化模型,该模型体现了土体刚度受压实系数显著影响的特性,且具有较好的适用性。Taking the soil mass in a diseased section of Baoshen Railway as the research object,the samples with different compaction coefficients and different water contents were prepared.GDS dynamic triaxial system was used to simulate the dynamic characteristics under water immersion.The self-developed mariotte bottle with constant water head was used to simulate the natural submersion of rainwater into the subgrade bed to build a dynamic humidification environment.The attenuation law of dynamic resilient modulus and the sensitive influencing factors of the subgrade bed for heavy haul railway under water immersion were studied.Results show that the immersion process will break the dynamic stability of soil and cause the continuous accumulation of plastic strain and the continuous attenuation of dynamic resilient modulus.The accumulation degree and attenuation law are significantly affected by the compaction coefficient.Under the action of immersion,the cumulative plastic strain of soil with 0.96 compaction coefficient is less than 3%when it is cyclically loaded up to 50000 times,while the cumulative plastic strains of soils with the compaction coefficients of 0.9 and 0.93 respectively are greater than 10%.The larger the compaction coefficient,the greater the attenuation degree of the dynamic resilient modulus of the soil under the action of immersion.The dynamic resilient modulus of the soil with the compaction coefficients of 0.9,0.93,and 0.96,respectively,decreases by 22%,32%and 42%under the action of immersion.The attenuation laws of cumulative plastic strain and dynamic resilient modulus of soils with different initial moisture contents are similar.Based on the test data,a model of soil softening under dynamic wetting is proposed,which is constructed by dynamic resilient modulus.The model reflects the characteristic that the stiffness of soil is significantly affected by the compaction coefficient,and has good applicability.

关 键 词：重载铁路 基床 动力湿化 动回弹模量 软化模型 

分 类 号：TU411.8[建筑科学—岩土工程] TU433[建筑科学—土工工程]