堆石料状态相关弹塑性本构模型

State-dependent elastoplastic constitutive model for rockfill materials

堆石料的强度变形特性与初始孔隙及应力状态等因素相关。建立了能够预测不同初始孔隙与初始围压影响的堆石料弹塑性本构模型。在剑桥类本构模型框架内,模型能够反映随着孔隙与围压的增大,变形特性由剪胀趋于剪缩的规律。模型采用了基于颗粒体材料细观结构变化的屈服函数和非关联流动准则,提出了能够反映堆石料正常固结线不唯一的硬化参数。为了反映状态相关性,假定堆石料存在唯一的临界状态面,探讨了考虑状态相关性需要满足的数学条件,从而对剪胀方程与硬化参数进行了修正。提出了基于粒子群优化算法的模型参数快速确定方法,将某筑坝堆石料不同初始孔隙比与围压条件下模型预测结果与三轴试验结果对比,验证了模型的合理性。

The strength and deformation characteristics of rockfill materials are related to the initial void ratio and confining pressure. In this study,an elastoplastic constitutive model for rockfill materials is established to predict the mechanical response of rockfill materials under different confining pressures and initial densities.Based on the framework of the Cambridge-type models,the proposed model can account for the transition from dilation to contraction shear response of rockfill materials as the void ratio or the confining pressure increases.The proposed model adopts a micromechanically-based yield function to characterize the evolution of the microstructure with the non-associative flow.A new hardening parameter is derived based on the fact that the virgin compression curves are not unique for rockfill materials.To characterize the state-dependent behavior,a unique critical state surface of rockfill material is assumed.The mathematic requirements for a general Cambridge-type constitutive model are summarized by considering the state dependence;furthermore,both the dilatancy equation and the hardening parameter are modified.A particle swarm optimization method is established to determine the model parameters,and the performance of the proposed constitutive model is verified by comparing with experimental results.