地震荷载作用下双层填土的主动土压力计算

Seismic active earth pressure on retaining wall with two-layer of cohesive backfill

针对挡土墙后为成层黏性填土的情况,提出一种地震土压力计算方法.在Mononobe-Okabe理论的基本假定下,考虑了填土黏聚力及墙土接触面上的黏着力,推导出双层填土的地震主动土压力计算表达式.在单层无黏性填土条件下,该公式可以退化为Mononobe-Okabe公式.参数分析结果表明:地震主动土压力随水平地震加速度的增大而增大,随竖向地震加速度的增大而减小;水平向和竖向地震荷载对土压力值的影响显著.算例分析结果表明原有的分层法计算得到的地震土压力值是偏大的.

An advanced computation approach was presented to study the seismic active earth pressure on retaining wall with two-layer cohesive backfill.Based on the assumption of Mononobe-Okabe theory,the expression for the total seismic active earth pressure was derived.The cohesion force on the sliding plane and the adhesive force on the interface of backfill and retaining wall were considered in the analysis.The developed formula can be degenerated to Mononobe-Okabe earth pressure expression for the case of homogeneous cohesiveless soil backfill.The parametric study shows that the seismic active earth pressure increases with the increase of horizontal seismic acceleration coefficient,while it decreases with the increase of vertical seismic acceleration coefficient.Both horizontal and vertical seismic inertia forces have significant effect on the value of seismic active force.Compared with the results of other methods for calculating the seismic earth pressure,the value of seismic active force obtained from the present study is lower than that of the layer method for the same parameters.