摘要
在矿山深部开采过程中,高应力与高水压耦合作用导致岩石的力学特性演化机理更加复杂.为分析深部复杂条件下花岗岩的力学行为及破坏特征,利用低场核磁共振核技术(NMR)进行花岗岩初始孔隙率测量,借助岩石高温三轴流变系统开展应力–渗流耦合试验,引入耗能比实现花岗岩破坏过程的能量演化分析.研究结果表明:岩石的峰值强度、峰值应变随孔隙水压的增大呈线性减小且减小速率逐渐提升,随围压的增大呈线性增加且增大速率逐渐变缓;峰值渗透率随着孔隙水压的增大呈线性增大,随围压的增大呈线性减小;岩石破坏应变能表现出明显的围压效应和孔隙水压效应,峰值应力点为弹性能极值点,峰值点之后弹性能迅速转化为岩石损伤的耗散能,岩石耗能比整体呈现增大→减小→增加的“S”型变化规律;引入花岗岩初始孔隙率,将岩石视为固体骨架和孔隙两部分组成,综合考虑变形特征并构建应力–渗流耦合本构模型,与试验对比后认为该模型具有较高普适性.
In the deep mining process,the coupling effect of high stress and high water pressure results in a more complex evolution mechanism of rock mechanical properties.In this work,the degradation effect of granite under complicated conditions is analyzed for analysis and failure characteristics by Nuclear Magnetic Resonance granite initial porosity measurement.A high-temperature triaxial rheological rock system was used to conduct the stress–seepage coupling experiment,introducing energy consumption than energy evolution of granite failure process analysis,and this is combined with the accurate and basic characteristics of the granite building stress–seepage coupling damage constitutive model.The findings reveal that the main pore in granite is the main cause of porosity change,which directly impacts the porosity size and sample strength.Porosity size is associated with secondary pores and main pores,and the porosity is difficult to be affected by the proportion of micropores.The peak strength and peak strain of rock decrease linearly with increasing pore pressure as the decreasing rate gradually increases and increase linearly with increasing confining pressure as the increasing rate gradually decreases.The peak permeability increases linearly with increasing pore pressure but decreases linearly with increasing confining pressure.Rock failure strain energy exhibits an evident confining pressure effect and pore water pressure effect.The peak stress point is the extreme point of elastic energy.After the peak point,the elastic energy rapidly transforms into dissipated energy of rock damage.The energy dissipation ratio increases in the early stage and decreases in the late stage with increasing confining pressure and increases overall with increasing pore pressure.The initial porosity of granite is introduced,and the rock is considered as the solid skeleton and the pore,and the initial nonlinear deformation of rock is employed to build the stress–seepage coupling constitutive model based on the deformation characte
作者
张超
杜翠凤
宋卫东
付建新
ZHANG Chao;DU Cuifeng;SONG Weidong;FU Jianxin(School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of High-Efficient Mining and Safety of Metal Mines(Ministry of Education),Beijing 100083,China)
出处
《工程科学学报》
EI
CSCD
北大核心
2024年第4期600-613,共14页
Chinese Journal of Engineering
基金
国家重点研发计划资助项目(2022YFC2905003)
国家自然科学基金资助项目(52274109)。
关键词
应力–渗流耦合
低场核磁共振
本构模型
破裂特征
能量耗散
stress–seepage coupling
nuclear magnetic resonance
constitutive model
rupture characteristics
energy dissipation
