有限宽度填土挡墙主动土压力的普适解法

Generalized solution to active earth pressure exerted onto retaining wall with narrow backfills

利用有限元极限分析方法(FELA),揭示了平动模式下有限宽度填土主动破坏机理。结果发现,有限土体条件下,填土主要呈现多滑裂面破坏机理,并呈“反射式”发展;同时总结了不同工况下滑裂面数量。据此,将有限填土划分为上部未滑裂区与下部滑裂区,考虑墙后土拱效应及层间单元水平剪切力作用,引入弯曲微分单元概念,并用于求解非滑裂区主动土压力;进一步考虑任意数量滑裂面,采用滑楔体极限平衡法和有限差分理论,得到了下部滑裂区主动土压力解;同时给出了主动土压力合力及其作用点高度计算表达式,系统地建立了有限宽度填土挡墙主动土压力的普适解法。通过与已有研究对比验证了所提方法的合理性与准确性。此外,分析了填土宽高比、填土内摩擦角及墙-土界面摩擦角对主动土压力分布及其合力和作用点高度的影响。结果表明,滑裂面数量显著影响主动土压力分布规律,采用所提方法利于有限宽度填土挡墙经济性设计。

The finite element limit analysis(FELA)method is used to interpret the active failure mechanisms of retaining wall with narrow backfills under translation mode.It is found from the numerical results that multiple slip surfaces will be developed in the narrow backfills in rebounding form.Moreover,the numbers of slip surfaces in various cases are summarized.Afterwards,based on the active failure mechanisms,the backfills are divided into the upper non-sliding zone and the lower sliding zone.Considering the soil arching effects and the horizontal shearing between adjacent elements,the concept of curved soil-layer element is introduced to calculate the earth pressures in non-sliding zone.The sliding-wedge method and the finite difference theory are further used to estimate the active earth pressure taking the number of slip surface into account.Also,the solution to the active thrust and its application point are deduced.The proposed analytical solutions are validated through the comparisons against the previous studies.Finally,the parametric studies considering the effects of aspect ratio,soil friction angle and wall-soil friction angle are performed.The results show that the number of slip surface significantly affects the distribution of the active earth pressure,and using the proposed analytical solution is beneficial to an economic design of retaining wall with narrow backfills.