考虑变形影响的重力式挡墙地震土压力分布

Distribution of seismic earth pressure on gravity retaining walls considering influence of deformation

利用汶川地震丰富的近场实震资料,分析总结了地震作用下挡墙的变形破坏模式,指出挡墙的变形模式与地基基础关系最为密切。位于岩质地基上的挡墙主要发生倾斜变形,位于土质地基上的挡墙则主要发生推移变形。在此基础上,基于温克勒地基模型,将土体看做是一系列弹簧和理想刚塑性体的组合体,分析得到了不同变形模式下挡墙地震土压力及其合力作用点的计算方法。结果表明:不同变形模式下挡墙的地震土压力分布特征各异,除平移模式外,其余变形模式下挡墙地震土压力随深度都呈非线性分布;位于岩质地基上的挡墙发生变形后地震土压力的合力作用点要比土质地基上的挡墙高。通过开展位于岩质地基和土质地基上挡墙的振动台模型试验,对文中提出的挡墙地震土压力计算方法进行了验证,发现试验结果和理论分析结果较相吻合。

The deformation failure modes of gravity retaining walls under earthquakes are investigated by using the near-field data in Wenchuan Earthquake. It is found that the deformation failure modes of the retaining wall more closely relate with the foundation. The wall on the rock foundation mainly exhibits inclination deformation, while the wall on the soil foundation mainly shows slip deformation. Based on the Winkler foundation model, the soil mass is viewed as the combination of a set of springs and ideal rigid plasticity objects, and the relevant methods for the seismic earth pressure and the point of resultant force for gravity retaining wall under different displacement modes are proposed. The results show that the distribution of seismic earth pressure can be expressed differently under different deformation failure modes, except the slip deformation, and that the distribution of seismic active earth pressure against retaining wall is nonlinear under the rest of the deformation failure modes. The point of resultant force for the gravity retaining walls on the rock foundation is higher than that of the walls on the rock foundation. Large-scale shaking table tests for gravity retaining walls on rock foundation and soil foundation are conducted to test the proposed theory. It is indicated that the experimental results are in accordance with the theoretical ones.