基于统计损伤理论的邓肯—张修正模型研究

Study on statistical damage theory-based modified Duncan-Chang model

由于邓肯—张EB模型没有考虑颗粒破碎损伤对材料变形及强度的影响,不能模拟堆石料应变软化的缺陷,故将统计损伤理论引入邓肯—张双曲线模型。通过探讨堆石料应力—应变曲线不同阶段损伤变量的规律,描述堆石料的损伤破碎过程,考虑其损伤阈值的影响,建立了邓肯—张修正模型表达式,该模型参数能通过试验数据拟合得出。经过验证,邓肯张修正模型在高围压下能较好的模拟堆石料破碎损伤的全过程,低围压下退化为常规邓肯—张模型。与传统邓肯—张模型、统计损伤模型、弹塑性模型及试验结果相比较,其形式简单、参数少。研究成果可应用于底部围压较大的高堆石坝分析,为堆石坝的设计计算提供参考。

As the impact from grain crushing damage on deformation and strength of materials is not considered, Duncan-Chang EB model cannot simulate the strain softening defect of the rockfill materials, the statistical damage theory is introduced into Dun- can-Chang hyperbolic model. Through discussion on the law of the damage variables of the different phases of the stress-strain curve of the rockfill materials, description of the damage crushing process of the rockfill and consideration of the impact from the damage threshold of the rockfill materials, the modified Duncan-Chang model is established; for which the parameters can be obtained from the fitting of testing data. Through verification, the modified Duncan-Chang model can better simulate the full process of the crushing damage of rockfill materials under high surrounding pressure, and regress to the conventional Duncan-Chang model under lower surrounding pressure. Compared with the conventional Duncan-Chang model, the statistical damage model and the elastic-plastic model, the model has the merits of simple form and few parameters. The study result can be applied to the high rockfill dam with large bottom surrounding pressure, thus provide a reference for the design calculation of rockfill dam.