多级支挡结构地震主动土压力的极限分析

多级组合支挡结构形式在高边坡防护工程中得到了广泛采用，但现有研究却较少涉及这种支挡结构形式的地震土压力计算问题。应用拟静力法和塑性极限分析上限定理，并且基于强度折减技术，推导了重力式挡墙与两级锚杆挡墙组合支挡结构形式的地震主动土压力及其系数的上限解。该上限解考虑了水平和竖向地震系数、墙背倾角、坡面形式及多级支护方式、土体黏聚力、土体与墙背的黏附力等诸多因素。二级锚杆挡墙实例分析表明：静力条件下主动土压力计算值与现有相关方法的计算结果一致，土的抗剪强度折减系数、上挡墙锚杆轴力等参数，对下挡墙地震主动土压力影响显著。二级组合支挡结构地震主动土压力影响参数敏感性分析表明：水平地震系数以及重力式挡墙墙高和倾角的敏感性较大，上挡墙锚杆的轴力和倾角等参数的敏感性相对较小

Limit analysis of seismic active earth pressure of multistage retaining structures

Multistage and combination retaining structures are employed widely in high slopes; but the seismic earth pressure calculation method of this kind of retaining structure is seldom studied. According to the pseudo-static method and the plastic limit analysis theory, the upper bound solutions are derived to calculate the seismic active earth pressure and its coefficient of three-stage retaining structures including gravity retaining wall and two-stage anchored retaining structures based on strength reduction technique. The following factors including horizontal and vertical seismic coefficients, the angle of the retaining wall back, slope surface shape and its multistage retaining structure, soil cohesion, adhesive strength between soil and retaining wall back are taken into account. The case study of two-step anchored retaining structures indicates that static active earth pressure agrees well with the available research; and the effects of the factors such as strength reduction coefficient and axial force of upper anchored retaining structure are significant on seismic active earth pressure of the lower. Sensibility analysis of seismic active earth pressure of gravity retaining wall combined with anchored retaining structure indicates that the sensibilities of horizontal seismic coefficient, height and angle of gravity retaining wall are significant; and the sensibilities of axial force and angle of upper anchored retaining structure are relative small.