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土的动力非线性实验一般给出无量纲动力剪切模量G/G_(max)与剪应变γ的关系曲线以及滞回阻尼比λ与剪应变γ的关系曲线。同时,在地震工程主要关心的周期范围(例如0.1—10秒)内的地震荷载频率对以上两类经验曲线的影响不明显。为了获得一个与以上实验结果相一致的应力-应变关系,本文提出了一种具有粘性、弹性及塑件三种效应的应力-应变关系物理模型——粘-弹-塑模型(Visco-Elasto-Plastic Model),简称VEPM。这一模型能同时拟台G/G_(max)-γ和λ-γ两条实验曲线,且能很好地满足它们与加载频率无关的要求。本文还将VEPM与以往模型进行了对比,讨论了VEPM的物理意义。最后,给出了将VEPM应用于土层地震反应计算的两个实例。
The nonlinear dynamic experiment of soil generally gives the relationship between the non-dimensional dynamic shear modulus G/G max and shear strain γ, and the hysteretic damping ratio λ and shear strain γ. At the same time, the frequency of seismic loading within the period of the main concerns of seismic engineering (eg, 0.1-10 seconds) has no significant effect on the above two types of empirical curves. In order to obtain a stress-strain relationship consistent with the above experimental results, this paper proposes a physical model of stress-strain relationship with three effects of viscosity, elasticity and plastic parts—visco-elastic-plastic model (Visco-Elasto- Plastic Model), referred to as VEPM. This model can simultaneously formulate two experimental curves of G/G_(max)-γ and λ-γ, and can well meet the requirements of their independent loading frequency. This article also compares VEPM with previous models and discusses the physical meaning of VEPM. Finally, two examples of the application of VEPM to soil seismic response calculations are given.