基于常规三轴循环加卸载压缩试验,分析了大理岩压缩变形过程中的变形特征、能量耗散及损伤演化规律。基于试验结果进行了大理岩弹塑性应变分离,试验结果表明随着轴向偏应力的增加,大理岩轴向弹性应变近似呈线性增加,而侧向弹性应变呈非线性增长。基于变泊松比的假定,建立了大理岩非线性弹性应力-应变本构关系,并据此分离辨识得到大理岩轴向和侧向塑性应变。采用等效应变理论,定义了大理岩损伤变量D,相应得到了大理岩三轴压缩变形破坏过程中的损伤演化特征,根据岩石损伤演化曲线可将大理岩三轴压缩变形过程分为3个阶段;分析了大理岩三轴压缩变形过程中的应变能特征,计算得到了大理岩压缩变形过程中的弹性应变能及耗散能,结果表明大理岩岩体单元耗散能与损伤变量增量ΔD之间呈较好的线性关系,二者均可用于描述大理岩压缩变形过程中的损伤破坏特征。
Abstract
The deformation characteristic, energy dissipation and damage evolution of marble during triaxial compression were studied via triaxial cyclic compression test. The axial strain of marble was separated into elastic strain and plastic strain. The axial elastic strain was in an approximate linear relation with axial stress, while the lateral elastic strain was in an evident nonlinear relation with axial stress. A nonlinear elastic constitutive relation between strain and the stress was proposed based on the assumption of changeable Poisson’s ratio, and on this basis the axial and lateral plastic strains during the whole loading process were identified. The damage variable D of marble was defined in line with the theory of equivalent strain, and accordingly, the damage evolution of marble during triaxial compressive deformation was acquired. The damage evolution was then divided into three stages according to the calculated damage values. Moreover, the elastic strain energy and dissipated energy in each loading-unloading cycle were calculated with finite simulate method. An obvious linear relation was found between the energy dissipation of rock quality unit and the damage increment ΔD, both of which could be used to describe the damage evolution during the whole loading process.
关键词
大理岩 /
三轴循环加卸载试验 /
非线性本构方程 /
损伤变量 /
岩体耗散能
Key words
marble /
triaxial cyclic compression /
nonlinear elastic constitutive relation /
damage variable /
energy dissipation
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基金
煤矿安全开采技术湖南省重点实验室开放基金资助项目(E21832)
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