无限倾斜填土非竖直墙背条件下地震主动土压力计算

Analysis of seismic active earth pressure of backfill with infinite inclined surface behind non-vertical retaining wall

计算地震条件下主动土压力的大小是挡土墙设计的重要内容之一,为了进一步拓展经典朗肯土压力适用范围,基于拟静力法和经典朗肯土压力分析思想,依据挡土墙后面无限倾斜填土受力状态,选取菱形微小单元体为研究对象,采用应力摩尔圆对单元体进行应力状态分析,在此基础上推导了无限倾斜填土非竖直墙背条件下地震主动土压力计算公式。分析结果表明,经典的朗肯土压力公式和倾斜填土面黏性土朗肯主动土压力公式只是该公式在静力条件下的特例;与现有多种地震主动土压力计算公式的结果进行了对比分析,发现该公式与Mononobe-Okabe公式的计算结果基本一致,与其他几种方法的最大差值不超过10%。此外,还分析了填土内摩擦角、黏聚力和竖向地震系数对地震主动土压力系数的影响规律。

Analysis of active earth pressure under seismic condition is one of important contents in the anti-seismic design of retaining walls. In order to expand the applicability of classic Rankine earth pressure theory, diamond unit body is investigated according to the mechanical characteristics of inclined backfill. On basis of Rankine＇s conjugate stress concept, the formulation of seismic active earth pressure considering cohesive soil and backfill slope is proposed based on Rankine classic earth pressure theory and Mohr-Coulomb yield criterion. The results show that the formulas of classic Rankine active earth pressure and Rankine active earth pressure of cohesive soil considering backfill slope are special cases of the proposed formulation. The proposed formulation yields comparable results to several existing calculation formulations for cohesive soil. The maximum error caused by different calculation methods does not exceed 10%. In addition, the vertical seismic coefficient and values of cohesion and soil internal friction angles have also been explored.