间歇循环荷载下粉土路基动力特性及累积变形研究  

Study on Dynamic Characteristics and Accumulative Deformation of Silty Subgrade Soil Under Intermittent Cyclic Loading

作　　者：吴遥杰 周浩东 宫全美[1] Wu Yaojie;Zhou Haodong;Gong Quanmei(Key Laboratory of Road and Traffic Engineering,Ministry of Education,Tongji University,Shanghai 201804,China;School of Civil Engineering,Central South University,Changsha 410083,China)

机构地区：[1]同济大学道路与交通工程教育部重点实验室,上海201804 [2]中南大学土木学院,湖南长沙410083

出　　处：《华东交通大学学报》2022年第4期1-9,共9页Journal of East China Jiaotong University

基　　金：国家自然科学基金项目(51978523)。

摘　　要：重载铁路路基包含的细粒土填料在列车荷载反复作用下会产生较大变形,影响列车运行安全。以往的动三轴试验将列车荷载视为连续动荷载,忽略了间歇效应的影响。针对粉土路基开展间歇循环加载动三轴试验,研究不同动应力幅值、含水率、加载振次、间歇时长及其相对系数(间歇时长与加载时长之比)、排水条件下累积变形的影响规律,分析其动力特性。分析试验结果,提出一种利用“双线性”确定土体临界动应力和临界含水率的方法,发现临界动应力比(临界动应力与围压之比)随含水率线性变化;荷载间歇时间越长、加载振次越少、间歇加载相对系数越大,土体累积变形越小;随着试验排水条件的优化,土体累积塑性变形依次减少,强度依次增大。以上研究为重载铁路路基动力稳定性评价,合理选择列车间歇时间提供了理论参考。The fine soil filler contained in the subgrade of heavy haul railway will produce large deformation under the repeated action of train load, which will affect the safety of train operation. The train load is regarded as a continuous dynamic load in previous triaxial tests without considering the time intermittent effect. In order to investigate the accumulative plastic deformation and its dynamic and hydraulic characteristics of silty subgrade soil with different dynamic stress amplitude, water content, loading vibration times, intermittent time and relative coefficient(the ratio of intermittent time to loading time), drainage conditions, an intermittent cyclic loading dynamic triaxial test is carried out. Through the analysis of the test results, a method for determining the critical dynamic stress and critical moisture content of the soil by bilinear method is proposed, the critical dynamic stress ratio(the ratio of critical dynamic stress to confining pressure) changes linearly with the moisture content is found. It is found that the longer the loading interval time and the less the loading vibration times and the larger the relative coefficient, the smaller the accumulative deformation of the soil. And with the optimization of drainage conditions, the accumulative plastic deformation of the soil decreases in turn, the strength increases sequentially. The above research provides a theoretical reference for evaluation of hydrodynamic stability of heavy haul railway subgrade and rational selection of train interval time.

关 键 词：铁路路基 粉土 动三轴试验 间歇荷载 累积塑性应变 

分 类 号：U451.4[建筑科学—桥梁与隧道工程]