大理岩应力脆性跌落系数的试验研究

EXPERIMENTAL STUDY ON COEFFICIENTS OF BRITTLE STRESS DROP OF MARBLE

岩石的应力–应变全过程曲线以峰值应力为界,通常分为破坏前区和破坏后区2个部分。由于岩石破坏后区的力学特性对诸多岩石类工程,如地下巷道、矿柱和岩爆等,具有重要的工程意义。因此,此方面的研究已受到理论界和工程界的重视。岩石的破坏后区一般处于非稳定状态,其力学响应难以用经典的应变软化模型来加以描述,而应采用脆塑性模型。使用RMT–150B型岩石力学试验系统,在轴向应变率保持为常数的条件下,对雅安大理岩进行常规三轴压缩破坏试验,得到不同围压下岩石的应力–应变全过程曲线。利用试验得到的应力–应变全过程曲线,获得大理岩的应力脆性跌落系数与围压的关系表达式,为采用非理想脆塑性模型对大理岩介质及其中的构筑物进行数值分析提供依据。

The complete stress-strain curve of rock could according to the peak stress. The post-failure mechanical engineering cases, such as underground excavation, pillar, be divided into pre-failure and post-failure regions characteristics of rock are important to many rock rock burst and so on. Therefore, the research on the post-failure characteristics of rock is of great significance to both theory and practice. In general, the post-failure region of rock shows instability in the mechanical response, which is difficult to be described by the strength softening model; and it should be described by the brittle-plastic model. Taking the axial strain rate as a constant, a series of triaxial conventional compress failure tests of Ya＇an marbles were performed by RMT - 150B rock mechanics test system; and the complete stress-strain curves of rock specimens under different confining pressurees were obtained. Utilizing the stress-strain curves, the relation functions between brittle stress drop and confining pressure of marble are obtained. The achieved results can provide references, when using brittle-plastic model, to the numerical analysis of marble and its structures as well.