单桩横向非线性动力响应的简化分析模型

A SIMPLIFIED MODEL FOR NONLINEAR RESPONSE ANALYSIS OF SINGLE PILES UNDER DYNAMIC LATERAL LOADS

根据迟滞非线性系统随机振动的基本理论,在动力Winkler地基梁模型的基础上,提出了一个新的研究单桩横向非线性动力响应的一维简化分析模型。其中,桩周土对单桩的横向非线性作用力由连续分布的非线性退化迟滞弹簧模拟,而运动过程中的能量耗散,则由与非线性弹簧并联的、频率相关的粘壶表示。该模型能够反映单桩非线性行为的主要特征,并可以揭示各种非线性因素,如,桩周土的迟滞效应、桩周土力学性能的退化、桩周土的屈服、桩土界面分离等,对单桩动力响应的影响。该模型采用的计算参数,可以由实际桩土系统的物理参数、被广泛采用的设计规范和经验公式加以确定。计算结果表明,该模型可以较好地模拟各种单桩土系统的横向非线性动力学响应。

According to the fundamental conception of random vibration of hysteretic system, a new one-dimensional simplified model is proposed to study the lateral nonlinear dynamic response of single piles. The beam-on-dynamic-winkler-foundation hypothesis is assumed in this paper. A series of distributed nonlinear hysteretic, degrading springs described by the Bouc-Wen model are combined with distributed viscous frequency-dependent dashpots placed in parallel. The lateral nonlinear action of the soil to the single pile can be simulated by the nonlinear springs and the energy dissipation in the motion is accounted for with the dashpots. It can capture the main characteristics of the nonlinear behavior of the single pile and reveal the important role of several nonlinear factors affecting the response of single pile with this model, such as effect of hysteresis, degradation and yielding of the soil surrounding the pile, and separation between soil and pile. The parameters of the proposed model are readily associated with the physical parameters governing the response of actual pile-soil system, and widely accepted code recommendations or empirical formulas are used for their estimation. The predictions of the model are in very good agreement with measured values from experiments.