基于直接位移的回填EPS混合土挡墙抗震设计方法

Seismic design method of retaining wall filled with EPS lightweight soil based on direct displacement

EPS混合土(EPSCS)是一种具有轻质、高强、环境友好等优良工程特性的土工材料,作为挡墙回填土可大大减小墙背所受到的侧向土压力。为更好的理解回填EPS混合土挡墙的抗震性能,针对EPS混合土的特点,从性态分析角度出发,基于直接位移的设计概念(direct displacement based design,简称DDBD)提出一种适合回填EPS混合土的挡墙抗震简化分析方法。结果显示,由抗震性态设计理论所得到的土压力和墙顶位移与试验结果吻合较好;土压力需求曲线可用于判断墙后土体是否达到主动极限平衡状态,较好地预测回填土裂缝的出现;挡墙的需求曲线与能力曲线的交点为挡墙发挥最佳性能的状态,可用于回填EPS混合土挡墙的性态抗震设计。

Expanded polystyrene composite soil(EPSCS)is a kind of geotechnical material with excellent engineering characteristics such as lightweight,high strength,and environmental friendliness.As a kind of backfilling material,EPSCS can significantly reduce the lateral earth pressure applied on the wall back.To better understand the seismic performance of retaining walls backfilled with EPSCS,in view of the characteristics of EPS mixed soil,a direct displacement based design(DDBD)is introduced to propose a suitable simplified seismic analysis method for retaining walls backfilled with EPSCS from the perspective of pefromance.The results show that the earth pressure and the displacement of wall top obtained by the seismic design theory based on DDBD proposed in this study are in good agreement with the experimental results.The earth pressure demand curve can well predict the occurrence of backfill cracks and can be used to judge whether the soil behind the wall reaches the active limit equilibrium state or not.The intersection point of the demand curve and capability curve of the retaining wall is the state that the retaining wall gives full play to its best performance.This study provides the reference for the seismic design of the retaining wall backfilled with EPSCS based on direct displacement.