考虑循环弱化的饱和黏土简化非线性模型

Simplified nonlinear model considering cyclic degradation of saturated clay

随着海洋工程建设的快速发展,海洋环境中的地基稳定性逐渐成为学者和工程师关注的热点问题,建立一个简化的饱和黏土循环加载模型对于长期循环荷载下海上构筑物的设计具有重要意义。针对饱和黏土的循环弱化特性,在Hardin-Drnevich等效非线性模型的基础上,建立了考虑循环弱化的饱和黏土简化非线性模型来描述循环加载下饱和黏土的应力-应变关系,模型中引入了由循环加载期间产生的累积塑性变形控制的强度和模量衰减比公式。通过参数分析,说明了形状参数?与n以及残余衰减比与衰减系数等参数的意义和作用。通过对文献中单向循环试验和双向循环试验结果的模拟,验证了该简化模型可以较好地描述循环加载时饱和黏土应力应变滞回圈的演变规律以及循环加载后饱和黏土的强度和刚度弱化现象。简化模型大大提高了计算效率,与传统的土体弹塑性模型相比更加便于工程应用。

With the development of offshore engineering in recent years, foundation stability in ocean environment has become a hot topic for scholars and engineers. It is important to set up a simple saturated clay cyclic model for design of offshore structures under long-term cyclic loading. According to cyclic degradation behavior of saturated clay, a simple nonlinear model considering cyclic degradation of saturated clay is developed based on Hardin-Drnevich equivalent nonlinear model. This model can be adopted to describe the cyclic hysteretic characteristic of saturated clay, in which a degradation law for strength and stiffness with accumulated plastic strain as a variable is introduced. The physical interpretations of shape parameters ? and n, as well as residual ratio and damping factor are illustrated through parameter analysis. This model is proved to be able to describe the stress-strain hysteresis loops of different shapes and different degradation laws for strength and stiffness of saturated clay well by simulating the results of one-way cyclic triaxial tests and two-way cyclic triaxial tests in the literatures. With higher calculation efficiency, this simple model will be more suitable for engineering application comparing with the traditional elastoplastic models of soils.