挡土墙地震主动土压力拟静力法的集中与分散模式对比  

Comparison of Concentrated and Dispersed Action Modes of Pseudo-static Method for Seismic Active Earth Pressure on Retaining Walls

作　　者：郑涛 肖世国[2] ZHENG Tao;XIAO Shiguo(Department of Geological Engineering,Southwest Jiaotong University,Chengdu 610031,China;Key Laboratory of High-speed Railway Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学地质工程系,成都610031 [2]西南交通大学高速铁路线路工程教育部重点实验室,成都610031

出　　处：《铁道标准设计》2022年第12期20-26,共7页Railway Standard Design

基　　金：国家自然科学基金项目(51578466);中铁二院工程集团有限责任公司科研项目(KSNQ213011);四川省交通运输科技项目(2020-A-01)。

摘　　要：采用拟静力法计算刚性挡土墙地震主动土压力时,地震惯性力的施加分为分散于土体各处与集中于滑动土楔体质心两种模式。为确定两种施加模式的计算结果差异,针对墙背倾斜、层状填土、表面条形荷载等一般条件下地震主动土压力问题,采用平行于土面的斜向条分方法,基于极限平衡条件推导分散和集中模式下土压力递推计算公式,可确定土压力大小及分布模式。实例分析表明,本文算法与振动台模型试验、数值模拟的结果较为一致;两种模式的地震主动土压力合力大小相等,但二者分布模式及合力作用点位置存在明显差异;集中模式的土压力作用点高于分散模式结果,随着水平地震系数由零开始逐渐增大,二者差异先增大后减小,当水平地震系数取0.2时,集中模式与分散模式的主动土压力作用点高度比分别为0.7、0.48~0.56,二者相差达到最大值;对于墙体稳定性及地基承载力检算,集中模式比分散模式的计算结果均偏安全。When the pseudo-static method is used to calculate the seismic active earth pressure on rigid retaining walls,the applied seismic inertia forces can be assumed as two modes,namely,the dispersed action in the slide mass and the concentrated action at the centroid of the slide wedge.In order to determine the difference of calculation results between the two modes for the seismic active earth pressure under general conditions including wall back inclination,layered backfill and surface strip load,an oblique slice method with each slice parallel to the soil surface is adopted to obtain recursive calculation formulas of the earth pressure in the dispersed and concentrated action modes based on limit equilibrium conditions.The proposed method can attain the magnitude and distribution mode of the seismic active earth pressure.Case analysis shows that the proposed results are consistent with those using shake table test and numerical simulation method.The values of the resultant force of seismic active earth pressure in the two modes are equal,but there are obvious differences in the distribution mode and the position of application point of the resultant.The application point via the concentrated mode is higher than that via the dispersed one.The difference between them first increases and then decreases with the increase of horizontal seismic coefficient from zero.If the horizontal seismic coefficient is assumed as 0.2,the ratio of the height of application point of the active earth pressure over the wall height is about 0.7 and 0.48~0.56 respectively in concentrated and dispersed modes,and the correspondingdifference between the two modes reaches the maximum.As for the wall stability and bearing capacity of the foundation,calculation results in the concentrated mode are both safer than those in the dispersed mode.

关 键 词：挡土墙 地震主动土压力 拟静力法 地震惯性力 集中模式 分散模式 墙体稳定性 

分 类 号：U213.15[交通运输工程—道路与铁道工程]