挡土墙地震主动土压力及其分布形式研究

Study on seismic active earth pressure and its distribution of retaining wall

物部理论认为地震主动土压力呈线性分布，而且作用点位于墙底以上1／3高度处，与实测结果相差较大。基于库仑土压力理论的平面滑裂面假定，根据挡土墙后滑裂土体的力矩平衡，引入了土体对地震的放大效应，提出了地震主动土压力作用点位置的确定方法，给出了地震主动土压力强度的理论公式，并分析了地震放大系数对地震主动土压力及其分布的影响。结果表明，如果不考虑地震放大系数，地震主动土压力值与物部理论的计算结果基本相同，可见物部理论是本文方法的一种特例；地震主动土压力作用点都位于墙底以上0．40—0．50倍高度处，与试验结果比较吻合，说明物部理论有待进一步完善；地震主动土压力强度是一种作用等价的非线性分布，沿墙高的分布形式接近于抛物线，最大值也不再恒定于墙底，在挡土墙的稳定性设计时应予以重视。

In the theory of Mononobe and Okabe, the distribution of unit seismic active earth pressure is linear andthe location of application point of total seismic active earth pressure is at H/3 from the base of retaining wall,which is different from test results. Based on the assumption of planar sliding surface in Coulomb＇s earth pressuretheory and the moment equilibrium of sliding soil behind retaining wall, the seismic amplification factor is intro-duced, the method determining the application point of total seismic active earth pressure is presented, the effectiveformula of unit seismic active earth pressure is proposed and the effects of seismic amplification factor on seismic ac-tive earth pressure and its distribution are analyzed. The results show that the total seismic active earth pressurewithout seismic amplification factor is identical with those from Mononobe theory, which indicates that the latter is aspecial case of the proposed method; the location of application point of total seismic active earth pressure is at0. 40 H - 0.50 H from the base of retaining wall, which is identical with Sherif＇ s experiments and proves that theproposed method is a further supplement of Mononobe＇s theory ; the distribution of unit seismic active earth pressurealong the wall is non-linear and approaches to a parabola, and the maximum value is not at the base, which shallbe paid attention during the stability design of retaining wall.