一个基于细观结构的粗粒料弹塑性本构模型

Microstructure-based elastoplastic constitutive model for coarse-grained materials

针对粗粒料的剪胀特性和强度非线性,在经典弹塑性理论框架内,建立了一个基于细观结构的粗粒料弹塑性本构模型。模型采用基于颗粒材料细观结构变化推导得到的屈服函数,在此基础上由非相关联流动法则得到的剪胀方程,结合粗粒料典型的三轴压缩试验结果,引入一种无黏性土的压缩模式,构造了能够统一描述粗粒料剪胀、剪缩特性的硬化参数。阐述了由常规三轴试验和等向压缩试验确定模型全部7个参数的方法。对3种粗粒料三轴压缩试验结果进行了预测,预测结果与试验结果吻合良好,说明模型能够合理地反映粗粒料的应力变形特性。

Considering the nonlinear characteristics of dilatancy and strength of coarse-grained materials, an elastoplastic constitutive model based on microstructures is established within the framework of classic elastoplastic theory. In the model, a yield function derived from the microstructure of granular materials is adopted, and a stress-dilatancy relationship is developed from the yield function with the non-associated flow rule. Based on the typical trixial compression test results of coarse-grained materials, a hardening parameter is proposed by introducing a compression model for cohesionless soils, which can describe both the dilantancy and the contraction of coarse-grained materials. The proposed model has 7 parameters, which can be determined by the conventional trixial compression tests and the isotropic compression tests. The proposed model is calibrated by modeling the trixial compression tests on three rockfill materials. It is found that the calculated values are in good agreement with the experimental data, indicating that the proposed model can reflect the stress and deformation characteristics of coarse-grained materials reasonably.