岩石失稳破坏的理论研究

Theoretic study of rock unstable failure

建立了单轴压缩下岩石的本构关系,在此基础上研究了尺度对岩石全程位移 荷载曲线的影响.研究表明,岩石材料的破坏并不等同于岩石 试验机系统已发生失稳破坏,而是其发生失稳破坏的前兆.增大岩石的长度或减小其直径相当于降低了试验机的"有效刚度",从而使得岩石 试验机系统更容易发生失稳破坏.而后基于岩石三轴压缩状态下的剪切破坏模型,建立了岩石失稳破坏发生的条件.理论分析表明,尽管试验机本身的刚度足够大,但岩石 试验机系统仍会发生失稳破坏,其根源在于岩石材料本身的失稳破坏,岩石失稳破坏的发生与其长度及所加围压相关,增大岩石的长度或减小其围压,均能使岩石由稳定破坏转化为失稳破坏.图7,参11.

In this paper, the constitutive relation under uniaxial compression loading is constituted, and on the basis of the equation,the effect of scale on complete displacementload curve is studied. Study shows that the failure of rock material does not mean the unstable failure of rocktesting machine system, but the portent of the unstable failure occurrence. Increasing the diameter or decreasing the length of rock is equivalent to lowering the 'effect rigidity' of the testing machine, and so made the rocktesting machine system happen the unstable failure more easily. Then based on shear failure model after the peak value under the triaxial compression stress state, the condition of rock unstable failure occurrence was established. The theory analysis shows that rocktesting machine system still will happen the unstable failure although the stiffness of testing machine is enough large. The failure of rocktesting machine unstable failure results from the unstable failure of rock material. The occurrence of unstable failure of rock is related to the length of rock and the confining pressure, but no large relation with the diameter of rock. The increasing of the length of rock or decreasing of the confining pressure can all make the rock transform from stable failure to unstable failure.7figs.,11refs.