循环加卸载过程中灰岩微细观损伤特征的试验研究OA北大核心CSTPCD
Experimental study of microscopic and mesoscopic damage features of limestone under cyclic loading and unloading
岩石的动力学性质是影响岩质边坡地震动力稳定性的关键内因.地震产生的循环往复作用会造成岩石损伤和破坏,劣化岩石性能,降低岩质边坡的稳定性.为了深入研究岩石在动力荷载下的损伤特征,以某岩质斜坡出露的二叠系灰岩为研究对象,联合单轴循环加卸载试验和微细观试验,从微细观角度研究了岩样在循环加卸载过程中的损伤特征和损伤演化规律,分析了不同加载条件对微细观损伤的影响,开展了宏观和微细观参数的关联分析.研究结果表明:岩样内部的损伤是一个渐进性过程,在破坏前,随着应力幅值和循环周次的增加,表现为以小孔隙的生成、扩展和贯通为主,大孔隙的数量轻微增加且数量相对少得多;与变上限应力加载相比,变下限应力加载更有利于小孔隙的连通和大孔隙的形成,导致岩样内部微裂隙面积更大,在宏观上表现为平均弹性模量的降低;在变上限应力时,低应力幅值的循环荷载对岩石内部结构劣化效应比单轴压缩条件下的大,而高应力幅值的循环荷载反而可能对岩石内部孔隙有一定压密作用,导致孔隙度相对较小,劣化效应相对减弱;综合多种微细观损伤变量演化趋势,可判断岩样在循环加卸载下经历了一段裂纹稳定扩展的阶段,对应的上限应力和下限应力范围分别为(0.4～0.6)σf(σf为静态峰值强度)和(0.3～0.5)σf.研究成果有助于从微细观层次更好地理解岩石的动力学特性,为岩质斜坡在地震作用下的动力响应行为和灾害孕育及启动过程提供理论解释.
The dynamic property of rock is a crucial internal factor which influences the seismic stability of a rock slope.Cyclic loading induced by an earthquake can lead to rock damage,deterioration in rock performance,and a decrease in slope stability.To investigate the dynamic damage characteristics of rock in-depth,this study examines Permian limestone samples obtained from a rock slope.Uniaxial cyclic loading and unloading tests,combined with microscopic and mesoscopic analyses,are conducted to study the damage features and evolution rules of rock specimens.The effects of different loading conditions on the microscopic and mesoscopic damage of rock specimens are analyzed,and the correlation between macroscopic,microscopic and mesoscopic parameters is investigated.The results reveal that rock damage is progressive,primarily characterized by the generation,propagation,and connection of micropores,followed by a slight increase in macropores,which are present in smaller quantities.Compared to cyclic loading with a variable upper limit stress,loading with a variable lower limit stress promotes greater connectivity of micropores and the formation of macropores,resulting in a larger microfissure area in the rock specimen and a decrease in the average elastic modulus.Under loading with a variable upper limit stress,low stress amplitudes have a more significant degradation effect on the internal structure of the rock compared to uniaxial compression.Conversely,high stress amplitudes may compact the internal pores of the rock,leading to relatively low porosity and weakened deterioration effects.By considering the evolution trends of different microscopic damage variables,a steady crack development phase is observed,with the corresponding upper limit stress range being 0.4-0.6 times the static peak strength(σf),and the lower limit stress range being 0.3-0.5 times the static peak strength.These research findings enhance our understanding of the dynamic characteristics of rock at the micro-and meso-levels.They also provide theoretical explanations for the dynamic behavior of rock slopes and the initiation process of disasters under seismic conditions.
刘汉香;叶刁瑜;别鹏飞;朱星
成都理工大学环境与土木工程学院,四川成都 610059成都理工大学计算机与网络安全学院,四川成都 610059
土木建筑
灰岩微细观损伤单轴循环加卸载试验核磁共振试验电镜扫描试验
limestonemicroscopic and mesoscopic damageuniaxial cyclic loading and unloading testnuclear magnetic resonance testscanning electron microscopy test
《岩土力学》 2024 (003)
685-696 / 12
四川省科技计划(No.2021YFSY0036);国家重点研发计划(No.2022YFC3003205,No.2019YFC1509602).This work was supported by the Sichuan and Technology Program(2021YFSY0036)and the National Key Research and Development Program(2022YFC3003205,2019YFC1509602).
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