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岩体结构非平衡演化的有效应力原理及长期稳定性分析 预览 被引量:1

EFFECTIVE STRESS PRINCIPLE OF NON-EQUILIBRIUM EVOLUTION AND LONG TERM STABILITY ANALYSIS OF ROCK MASS STRUCTURE
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摘要 开挖卸荷后的天然岩体往往处于非平衡演化状态,将直接影响岩体工程结构的正常运行、长期稳定和安全.时效变形和损伤演化是岩体结构非平衡演化的核心.在赖斯(Rice)内变量热力学理论框架下,提出了岩体结构非平衡演化的有效应力原理,指出有效应力是总应力中能有效驱动结构演化的部分.将内变量率形式的非弹性应变率方程和能量耗散率函数表示为有效应力形式,并提出非弹性余能概念.给定具体的余能密度函数和内变量演化方程,得到了考虑损伤的内变量黏塑性应变率方程.通过相似材料加卸载蠕变试验结果进行参数辨识,并分别计算了内变量率形式和有效应力形式的黏塑性应变率、能量耗散率和非弹性余能,并对其进行比较分析.结果表明:在过渡蠕变和稳态蠕变阶段两种形式的方程计算的黏塑性应变率几乎相等,但在加速蠕变阶段两者相差较大;非弹性余能和能量耗散率全域积分分别从驱动结构非平衡演化的内在潜力和实际效果的角度表征了结构的非平衡演化状态和演化趋势,能量耗散率积分更合适用于评价岩体工程结构的长期稳定性.最后以深埋地下洞室作为工程算例,并对其长期稳定性进行分析. After excavation, the disturbed natural rock mass tends to be in non-equilibrium evolution state and affects the safety and stability of engineering structure. The time-dependent deformation and damage evolution are the cores of the non-equilibrium evolution process of rock mass structure. In this paper, the effective stress principle of non-equilibrium evolution is proposed within thermodynamics with internal state variables. The effective stress, which can really derive non-equilibrium evolution process, is only a portion of total stress. The rate of inelastic strain and energy dissipation rate can be expressed in form of effective stress, and concept of inelastic complementary energy is proposed. A creep constitutive equation with damage is derived through giving specific complementary energy density function and evolution function of internal state variables. Parameters identification of degraded one-dimension equation is conducted under one dimensional scene through uniaxial creep test of analogue material by load and unload method. Viscoplastic strain rate, rate of energy dissipation and inelastic complementary energy can be calculated, and the comparative discussion is illustrated. The results indicate that the difference between rates of inelastic strain is minor in primary and secondary creep stages but is major in tertiary stage because of theoretical error. The integral value of rate of energy dissipation in domain and inelastic complementary energy can characterize the non-equilibrium process of structure in actual effect and driving potential perspective respectively, and the latter is a more applicable one to assess the long-term stability of structure. At last, a case about deep buried tunnels is shown and its long-term stability is studied.
作者 张泷 刘耀儒 杨强 Zhang Long,Liu Yaoru,Yang Qiang(State Key Laboratory ofHydroscience and Engineering, Tsinghua University, Beijing 100084, China)
出处 《力学学报》 EI CSCD 北大核心 2015年第4期624-633,共10页 chinese journal of theoretical and applied mechanics
基金 国家自然科学基金项目(11172150,51279086) 水沙科学与水利水电工程国家重点实验室科研项目(2013-KY-2) 教育部新世纪优秀人才支持计划(NCET-13-0323)资助)
关键词 有效应力 内变量热力学 非弹性余能 能量耗散率 长期稳定性分析 effective stress thermodynamics with internal state Variable inelastic complementary energy energy dissi-pation rate long-term s
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