摘要
为研究三轴循环加卸载条件下花岗岩破坏全过程的宏细观力学特性,采用颗粒流PFC3D方法确定了应力-应变曲线上的应力门槛值(σ_(ci)起裂应力、σ_(cd)裂隙损伤应力和σ_f峰值强度),分析了宏观参数随塑性剪切应变的变化规律,并结合微裂纹数目及微裂纹发展变化过程,揭示了微裂纹损伤演化规律。结果表明:宏观上,不同围压下相应的σ_(ci)/σ_f分别为49.59%、49.7%、36.3%,σ_(cd)/σ_f分别为91.74%、95%、96.2%;应力门槛值和弹性模量随塑性剪切应变的增加先快速减小后趋于稳定,泊松比随塑性剪切应变的增加先快速增大后趋于稳定。细观上,微裂纹数目最大增量发生在应变软化阶段;试样内部微裂纹的发展是通过其自身扩展实现的,且微裂纹的扩展同时受试样结构和试样内主应力方向的影响;不同围压下试样均在残余变形阶段发生剪切破坏。研究结果很好地揭示了试样在循环荷载作用下破裂的全过程。
In order to study the macro-micro mechanical properties of granite failure under triaxial cyclic loading and unloading,the critical thresholds(the crack initiation stressσci,the crack damage stressσcdand the peak stressσf)on stress-strain curves were determined,the variation law of macroscopic parameters with the plastic shear strain was analyzed,and the damage evolution law of micro-cracks was revealed by combining the number of micro-cracks and the process of micro-cracks propagation based on PFC3D method.The results showed that,from macro perspective,the correspondingσci/σf under different confining pressures was 49.59%,49.7%,36.3%,respectively,andσcd/σf was 91.74%,95%and 96.2%,respectively.With the increase of plastic shear strain,the critical thresholds stress and elastic modulus decreased rapidly and then tended to be stable,while the Poisson’s ratio increased rapidly and then tended to be stable.From micro perspective,the maximum increment of the number of micro-cracks occurred during the strain softening stage.The development of the microcracks was realized by its own expansion,which was affected by both the specimen structure and the principal stress direction in the specimen.Moreover,the shear failure occurred in the residual deformation stage under different confining pressures.The research results well revealed the whole process of specimen damage under cyclic loading.
作者
张英
丁忠岐
房铖
丛滨亭
ZHANG Ying;DING Zhongqi;FANG Cheng;CONG Binting(School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China;State Key Laboratory of the Education Ministry for High-Efficient Mining and Safety of Metal Mines,Beijing 100083,China;Sanshandao Gold Mine,Shandong Gold Mining Industry(Laizhou)Co.,Ltd,Laizhou,Shandong 261400,China)
出处
《矿业研究与开发》
CAS
北大核心
2019年第4期52-58,共7页
Mining Research and Development
基金
国家重点研发计划项目(2016YFC0600703
2017YFC0804101)
中央高校基本科研业务费专项资金资助项目(FRF-TP-16-017A3)
国家自然科学基金项目(51604017
51774022)
关键词
花岗岩
三轴循环加卸载
塑性剪切应变
微裂纹
颗粒流模拟
Granite
Triaxial cyclic loading and unloading
Plastic shear strain
Micro-crack
Particle flow simulation
