单轴压缩下岩石破坏后区的扰动状态概念分析

岩石的应力一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两个部分。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强度理论来描述。由于岩石破坏后区的力学特性对诸多岩石工程，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。基于扰动状态概念理论，通过定义相对完整状态、完全调整状态和扰动函数，建立了能反映岩石材料破坏后区特性的本构模型。采用RMT-150B型岩石力学试验系统，对5种岩石试样(湖北大悟的红花岗岩、四川雅安的大理岩、江西贵溪的红砂岩、河南焦作的砂岩和花岗岩)进行了单轴压缩破坏试验，得到了各种岩石的应力-应变全过程曲线；利用扰动状态概念分析了各岩样变形和破坏的力学机理。在提出的岩石材料扰动状态本构模型的基础上，对上述几种岩石破坏后区的应力-应变关系进行了数值计算，计算结果与试验结果较为一致。因此，建立的本构模型在一定程度上能描述岩石破坏后区的力学特性。

ANALYSIS ON POST-FAILURE BEHAVIORS OF ROCK IN UNIAXIAL COMPRESSION USING DISTURBED STATE CONCEPT THEORY

The complete stress-strain curve of rock could be divided into pre-failure and post-failure regions according to the peak stress. In general,the pre-failure region of rock shows stability in the mechanical response,which may be described by the classic strength theories,and the post-failure region of rock shows instability,which is difficult to be described by the classic strength theories. The post-failure mechanical characteristics of rock are corresponding to a good many rock engineering,such as underground excavation,pillar,rock burst and so on. Therefore,the research on the post-failure characteristics of rock is of important significance both in theory and in practice. Based on the disturbed state concept theory (Desai,2001),it is assumed that the relative intact state of rock is of hyperbolic form and the fully adjusted state of rock is the critical state of rock failure. A new constitutive model reflecting the post-failure behaviors of rock material is established through defining the expression of disturbance function. A series of uniaxial compressive failure tests about five kinds of rock specimens were performed by RMT-150B rock mechanics test system. The complete stress-strain curves of the five kinds of rock specimens were obtained. The mechanical mechanism of the deformation and failure in rocks is studied using the disturbed state concept. The proposed constitutive model is applied to simulate the post-failure behaviors of rock specimens. From correlative study and analysis,it is shown that the proposed constitutive model can predict,in a certain extent,the mechanical characteristics of rock in post-failure region.