南京工业大学学报（自然科学版）2025，Vol.47Issue(5)：543-550,569,9.DOI:10.3969/j.issn.1671-7627.2025.05.008
钙质砂剪切力学特性的粒组效应与颗粒破碎机制
Particle gradation and breakage mechanisms in the shear mechanics of calcareous sand
摘要
Abstract
Calcareous sand exhibits significant particle gradation in its mechanical behavior.Its inherent fragility under load changes the particle size distribution,further increasing the structural complexity of particle gradation.In this study,direct shear tests were conducted on three types of particle gradation under three levels of normal stress(100,200,and 400 kPa)using a high-precision acoustic emission(AE)system.The results show that,with increasing particle size,the stress-strain response transitions from strain softening to strain hardening,while the failure mode evolves from overall shear failure to localized shear or shear-compression failure.Influenced by the micro-mechanical behavior of particles in the shear band(interparticle slip and breakage,etc)and stress distribution,shear modulus,shear strength,and parameters such as apparent cohesion and internal friction angle first decrease and then increase with particle size.The relationship between the AE event rate and shear displacement showed good consistency with the shear stress-displacement relationship.Direct shear of calcareous sand under high normal stress and large particle gradation produces more AE events.The cumulative number of mid-to high-frequency AE events(＞100 kHz)shows a linear relationship with the relative potential for breakage(Br),providing a quantitative method for characterizing particle breakage.Particle grinding occurred throughout the entire direct shear process of calcareous sand.In the direct shear tests exhibiting strain-softening behavior,only a small number of particles underwent through-cracking or corner breakage,mostly around the peak stress.By contrast,in the tests exhibiting strain-hardening behavior,a larger number of particles experienced through-cracking and corner breakage,which persisted throughout the entire shear process.These findings offer theoretical and methodological support for understanding the mechanical behavior and failure mechanisms of calcareous sand.关键词
钙质砂/初始级配/颗粒破碎/声发射/剪切力学特性/频率响应Key words
calcareous sand/initial particle size distribution/particle breakage/acoustic emission(AE)/shear behavior/frequency response分类
建筑与水利引用本文复制引用
刘昂,何德祺,李迪,戴天宇,陈宇航,何家兴,林文丽..钙质砂剪切力学特性的粒组效应与颗粒破碎机制[J].南京工业大学学报（自然科学版）,2025,47(5):543-550,569,9.基金项目
国家自然科学基金(42472347) （42472347）
