花岗岩损伤型黏弹性动态本构模型研究

Research on damage viscoelastic dynamic constitutive model of granite

采用恒应变率SHPB实验装置对花岗岩的动态力学性能进行测试。结果表明:花岗岩动态应力-应变曲线在初始加载段呈线弹性,屈服后具有显著的塑性变形特征,屈服应力、峰值应力和弹性模量均具有应变率相关性。基于花岗岩动态力学特性,将朱-王-唐(ZWT)模型本构方程推广到花岗岩材料并对其进行简化,同时考虑冲击荷载作用下损伤对花岗岩动态强度的影响,引入应变率型损伤演化方程,建立简明的损伤型ZWT动态本构模型。应用建立的动态本构模型对SHPB实验测得的应力-应变曲线进行拟合,两者具有较好的一致性,表明构建的动态本构模型能够较好地反映花岗岩在动载作用下的力学特性。

Dynamic mechanical properties of granite were tested by a split Hopkinson pressure bar system with constant strain rate.The initial loading stage of stress-strain curve of granite is linear elasticity,and the rock material has a significant plastic deformation after yielding.Yield strength,peak strength and elastic modulus are all rate dependent.Based on dynamic mechanical property of granite,the constitutive of Zhu-Wang-Tang model was simplified to apply on granite,and with consideration of the effect of damage on the dynamic strength of granite under impact load.The experimental data were fitted to the proposed model.The fitted stress-strain curves at different strain rates are in good agreement with the experimental ones.This demonstrates that the proposed dynamic constitutive model in this paper can accurately describe the dynamic mechanical properties of granite under the impact load.