考虑时间间歇效应的粉土动力特性  

Dynamic Characteristics of Silt Considering Time Intermittent Effect

作　　者：聂如松[1,2] 董俊利 梅慧浩[1] 冷伍明[1,2] 李亚峰 程龙虎 NIE Rusong;DONG Junli;MEI Huihao;LENG Wuming;LI Yafeng;CHENG Longhu(School of Civil Engineering,Central South University,Changsha 410075,China;MOE Key Laboratory of Engineering Structures of Heavy Haul Railway,Central South University,Changsha 410075,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学重载铁路工程结构教育部重点实验室,湖南长沙410075

出　　处：《西南交通大学学报》2021年第5期1125-1134,共10页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金(51878666,51678572);中国铁路总公司系统性重大项目(P2018X011)。

摘　　要：列车荷载是揭示路基真实动力响应特性的前提,以往的动三轴试验将列车荷载视为连续动荷载,忽略了追踪列车间隔时间对路基土体动力特性的影响.利用室内动三轴仪对粉土开展了连续加载和间歇加载(连续加载与间歇交替循环)的动三轴试验,分析了两种加载方式下粉土超孔隙水压力、回弹模量、累积塑性应变等的发展规律.研究结果表明:持续动荷载作用下累积的超孔隙水压力在间歇阶段会发生消散,轴向应变在间歇阶段得到一定程度恢复,进而提高了试样抵抗变形的能力;室内动三轴试验忽略间歇效应将高估列车动荷载作用下试样超孔压和塑性应变的累积量及发生破坏的可能性;间歇加载下试样的永久变形行为可依据安定理论划分为塑性安定、塑性蠕变和增量破坏.Train dynamic load is the premise to reveal the real dynamic response characteristics of subgrade.The train load is regarded as a continuous dynamic load in previous cyclic triaxial tests without considering the time intermittent effect.Dynamic triaxial tests of silt under continuous loading and intermittent loading(continuous loading and intermittent alternating circulation)were carried out by using indoor dynamic triaxial apparatus,and the development laws of excess pore water pressure,modulus of resilience and accumulated plastic strain of silt under two loading modes were analyzed.The accumulated excess pore water pressure under continuous dynamic load will dissipate in the intermittent stage,and the axial strain will be restored to a certain extent in the intermittent stage,thus improving the ability of the sample to resist deformation.Ignoring intermittent effect in indoor dynamic triaxial tests will overestimate the cumulative amount of excess pore pressure and plastic strain and the possibility of failure.The permanent deformation behavior of specimens under intermittent loading can be divided into plastic stability,plastic creep,and incremental failure according to stability theory.

关 键 词：列车动荷载 动三轴试验 时间间歇 超孔隙水压力 累积塑性应变 安定理论 

分 类 号：U213.1[交通运输工程—道路与铁道工程]