摘要
支护结构不可避免地修建在既有建筑物附近以保持有限土体稳定性。为研究墙后有限土体的被动土压力,使用有限元极限分析法探讨挡墙的破坏模式,为建立理论计算模型提供依据。以有限宽度黏土为研究对象,假定滑裂面为通过墙踵的直线形,且在绕墙底转动位移模式下,墙后土体形成圆弧形主应力拱。采用沿简化主应力迹线分层的方法,将挡墙后土体划分为若干倾斜薄层单元,考虑挡墙位移和单元上下界面应力分布不均匀性,提出一种计算绕墙底转动模式挡墙有限土体被动土压力计算方法,给出被动土压力合力及其作用点高度的解析解,并验证该方法的可靠性。研究结果表明,采用倾斜薄层单元法可以较好地考虑土体单元受力特征,更好地反映挡墙后有限土体在转动模式下的被动土压力变化规律;有限土体土压力沿深度呈单调递增的趋势,靠近墙底处土体土压力增幅增大。综合考虑土体黏聚力、内摩擦角、墙土摩擦角和填土宽高比B/H参与敏感性分析,当B/H<1.76时,随着宽高比的增加,被动土压力逐渐减小,合力作用点高度逐渐升高,减小土体内摩擦角φ以及土体黏聚力c都有助于挡墙被动土压力的减小;当B/H≥1.76时,被动土压力及合力作用点高度均趋于稳定,对于任意宽高比土体,减小宽高比B/H与黏聚力c,增大摩擦角φ和δ,都将降低被动土压力合力作用点高度。
Retaining structures are inevitably constructed near existing buildings to maintain the stability of limited soil masses.To investigate the passive earth pressure of the limited soil behind the retaining wall,the finite element limit analysis method was employed to explore the failure mode of the wall and provide a theoretical basis for model development.The study focused on finite-width clay,assuming a straight sliding surface through the heel of the wall.Under a rotational displacement mode around the wall base,the soil behind the wall was assumed to form a curved principal stress arch.A layering method along simplified principal stress traces was used to divide the soil behind the retaining wall into several tilted thin-layer units.Considering the wall displacement and the uneven stress distribution at the upper and lower interfaces of each unit,a method for calculating the passive earth pressure of limited soil under the rotation-around-wall-base mode was proposed.Analytical solutions for the resultant force of the passive earth pressure and its point of action were derived,and the reliability of the method was verified.The results showed that the tilted thin-layer unit method effectively captured the stress characteristics of soil elements and more accurately reflected the variation pattern of passive earth pressure in limited soil under rotational conditions.The passive earth pressure of limited soil increased monotonically with depth,with a sharper increase near the wall base.A sensitivity analysis was conducted considering soil cohesion,internal friction angle,wall-soil friction angle,and the aspect ratio B/H.When B/H was less than 1.76,increasing the aspect ratio resulted in a gradual decrease in passive earth pressure and a corresponding rise in the height of the resultant force point.Reducing the internal friction angleφand soil cohesion c also contributed to reducing the passive earth pressure acting on the retaining wall.When B/H was greater than or equal to 1.76,both the passive earth pressure and the height of its resultant force tended to stabilize.For soils of any aspect ratio,reducing the aspect ratio B/H and soil cohesion c,and increasing the friction angleφandδ,all help to lower the height of the resultant force point of passive earth pressure.
作者
李新军
LI Xinjun(China Railway Siyuan Survey and Design Group Co.,Ltd.,Wuhan 430063,China)
出处
《铁道标准设计》
北大核心
2025年第9期48-58,71,共12页
Railway Standard Design
基金
国家重点研发计划项目(2023YFC3009304)
中铁第四勘察设计院集团有限公司科技研究开发计划课题(KY2023024S)。
关键词
挡土墙
有限土体
被动土压力
主应力迹线
倾斜薄层单元
retaining wall
limited soil
passive earth pressure
principal stress trace
tilted thinlayer unit
