黄土场地中桩—土动力相互作用机理及地震响应规律研究

为研究黄土地区桩-土相互作用机理及其对结构地震响应规律的影响,根据黄土非线性动力本构关系,构建可考虑桩-土界面滑移、分离和碰撞的简化理论模型,推导出理论模型中各特征指标的计算公式。结合桩-土动力相互作用基本原理,推导建立了桩-土-结构动力体系运动方程,对考虑桩-土相互作用和不考虑桩-土相互作用的黄土场地独柱式桥墩进行了地震响应分析。结果表明:桩-土相互作用力学模型正确与否是准确分析结构动力响应的关键;桩-土相互作用能够降低结构自振周期,改变结构动力特征,使得结构对低频地震波具有更高的敏感性,从而影响结构动力响应规律;桩-土相互作用也降低了结构抗侧移刚度,从而导致结构发生较大的位移响应,但同时也增强了结构的抗震消能能力。

Study on Dynamic Interaction Mechanism and Seismic Response of Pile-soil in Loess Site

In order to study the mechanism of pile - soil interaction in loess area and its influence on the seismic response of structure, according to the loess nonlinear dynamic constitutive relation, set up a considering interface slip pile - soil, separation and collision of simplified theoretical models, deriving the theoretical calculation formula of each characteristic index in the model. Based on the basic principle of pile-soil dynamic interaction, the kinetic equation of pile-soil-structure dynamic system is deduced, and analysis the seismic response of single pier with the consideration pile-soil interaction or not considering. The results show that the correctness of pile-soil interaction model is the key to accurately analyze the dynamic response of the structure. Pile-soil interaction can reduce the period of structural vibration and change the structural dynamic characteristics, which make the structure more sensitive to low frequency seismic waves, and the dynamic response irregular of the structure is affected. The pile-soil interaction also reduces the lateral stiffness of the structure, which results in a large displacement response, and also enhances the seismic energy dissipation capacity of the structure.