考虑应变局部化的粗粒料剪切损伤力学机制  

Shear damage mechanism of coarse-grained materials considering strain localization

作　　者：赵顺利 杨之俊 傅旭东[1] 方正[1] ZHAO Shun-li;YANG Zhi-jun;FU Xu-dong;FANG Zheng(School of Civil Engineering,Wuhan University,Wuhan,Hubei 430072,China;Yellow River Engineering Consulting Co.,Ltd.,Zhengzhou,Henan 450003,China)

机构地区：[1]武汉大学土木建筑工程学院,湖北武汉430072 [2]黄河勘测规划设计研究院有限公司,河南郑州450003

出　　处：《岩土力学》2023年第1期31-42,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.51978540)。

摘　　要：针对粗粒料的应变软化、剪胀等力学特性,通过考虑以剪切带为标志的应变局部化现象,建立了具有广泛适用性的剪切损伤力学模型。损伤模型采用了包体理论中的剪切带数学简化,基于应变等价原理、Weibull分布,推导了粗粒料的应力-应变关系方程。从剪胀作用的机制出发,提出可以描述剪胀弱化的轴向塑性应变和体积塑性应变的非线性函数关系。结合粗粒料三轴压缩试验中的伺服过程,提出了基于遗传算法的损伤模型参数确定方法。通过开展不同围压下的粗粒料三轴压缩试验,对剪切损伤力学模型进行验证,进一步分析了参数演化对粗粒料强度和变形特征的影响。研究结果表明,考虑应变局部化特征的剪切损伤力学模型可以高精度的模拟粗粒料的应变软化和剪胀等特征,有效揭示剪切带内部变形对试样整体宏观变形的影响机制,模型中剪切带参数和围压的关系与粗粒料细观机制一致,计算得到强度组成与颗粒破碎、重组特征较为吻合。In view of the mechanical properties of coarse-grained materials, such as strain softening and dilatancy, a generalized shear damage mechanical model with wide applicability was established in this study by considering the strain localization phenomenon marked by shear band. This damage model adopted the mathematical simplification of shear band in the envelope theory, and the stress-strain relationship equation of coarse-grained material was derived based on the strain equivalence principle and Weibull distribution. A nonlinear functional relationship between axial and volumetric plastic strain was proposed to describe the weakening of dilatancy based on the mechanism of dilatancy. Combined with the servo process of coarse-grained materials in triaxial compression tests, a method to determine the parameters of damage model was proposed based on genetic algorithm. By conducting a series of triaxial compression tests under different confining pressures, the shear damage mechanical model was validated, and the effects of the evolution of shear band parameters on the strength and deformation characteristics of coarse-grained materials were further analyzed. The results indicate that the proposed shear damage mechanical model considering the strain localization characteristics can accurately simulate the strain-softening and dilatancy characteristics of coarse-grained materials, and effectively reveal the influence mechanism of the internal deformation of the shear band on the overall macroscopic deformation of the coarse-grained sample. The evolution of the shear band parameters with the surrounding confining pressures in the model was consistent with the mesoscopic mechanism of coarse-grained materials. The strength composition calculated by this model was in good agreement with the micro mechanism, such as the breakage and reorganization of coarse-grained particles.

关 键 词：粗粒料 剪切损伤 应力-应变关系 应变局部化 应变软化 剪胀 

分 类 号：TU411[建筑科学—岩土工程]