地震作用下临近边坡的条形基础极限承载力研究

Seismic bearing capacity of strip footings adjacent to slopes

地震荷载对基础的极限承载力起着不利影响,但目前尚缺少系统的关于地震作用下的边坡地基极限承载力的研究。极限分析法是一种解决复杂岩土问题的严格分析方法,利用基于极限分析上限法的(discontinuity layout optimization(DLO))数值模拟技术,通过拟静力法考虑水平地震作用,对置放于边坡顶部条形基础的极限承载力进行研究,给出了地震荷载作用下临近边坡条形基础的极限承载力系数设计图,可用于地震荷载作用下边坡地基极限承载力的初步估算。研究表明,与水平地基不同,边坡地基的承载力研究同时涉及边坡稳定和极限承载力两类岩土工程问题,土体自重、内摩擦角及黏聚力均会对其产生耦合影响。已往研究中承载力系数的计算沿用水平地基研究方法对Nc,Nγ进行独立计算,并线性叠加计算极限承载力,未考虑边坡稳定问题对承载力研究带来的复杂性,对c–φ型边坡的极限承载力造成低估。

The seismic load has an adverse effect on the bearing capacity of the footings. However, few studies are performed to study its impact on the bearing capacity of slopes. In this study, a rigorous analysis in the framework of the upper-bound limit state plasticity, known as the discontinuity layout optimization(DLO), is adopted to investigate the performance of footings placed on the top of slopes considering the horizontal seismic action by the pseudo-static method. A set of design charts containing the horizontal seismic acceleration are presented for preliminary estimates. The results show the differences from the horizontal foundation, c, φ and γ of foundation soil will produce coupling actions for this problem. But in the existing researches, Nc and Nγ are calculated separately and linearly superposed without considering the complexity of slope projects, thus the bearing capacity of c–φ slope is underestimated.