压缩和劈裂荷载作用下岩石最大伸长应变差异的试验研究

从力学机制上看,岩石破坏可分为剪切破坏和拉伸破坏两种基本形式,它们各自都有不同的破坏准则,其中最大正应变强度准则是一个应用相对比较简单的岩石破坏准则。最大正应变强度准则判据建立的关键是如何标定极限伸长应变Σ_0。岩石在压应力和拉应力作用下都有可能发生符合最大(伸长)正应变准则的破坏。根据弹性理论,岩石在受拉和受压时对应的最大正应变临界值是等价的。然而,由于岩石材料的复杂性,岩石实际受压与受拉导致最大正应变形式的破坏所对应的最大正应变会有较大的差别。通过试验,本文揭示了不同种类的岩石在受拉、受压破坏时最大伸长应变的差异以及受压和受拉条件下岩石最大拉伸应变的理论值和试验值之间的差异。

EXPERIMENTAL RESEARCH ON THE DIFFERNENCE BETWEEN MAXIMUM TENSILE STRAINS OF DIFFERENT ROCK SPECIMENS UNDER UNIAXIAL COMPRESSINGAND SPLITTING LADS

In mechanism, there are two basic forms of rock failure, i.e., shear failure and tensile failure. Relative to different failure forms, different failure criteria can be set up. Among various rock failure criteria, the maximum tensile strain criterion based on tensile failure mechanism is the simplest one. The key problem about the maximum tensile strain criterion is how to calibrate the maximum tensile strainΣ_0. The rock failures coinciding with the maximum tensile strain criterion may occur both under compressing stress and under tensile stress. According to elasticity theory, the maximum tensile train under compressing stress is equal to the maximum tensile strain under tensile tress. In fact, however, because of the complexity of rock materials, the actual maximum tensile strains under compressing tress and tensile stress are quite different. By experiments, what are revealed in this paper are the differences between the maximum tensile strains of different rock specimens and the differences between the theoretical values and experimental values of maximum tensile strains of different rock specimens under compressing stress and tensile stress.