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本文介绍单轴压缩圆柱状岩石试件内应力状态的一种轴对称有限元分析成果。由于采用了节理单元模拟试件端部的接触边界,可反映出变形过程中试件同接触材料的相对错动,因此得到的结果比前人的分析更合理。其次本文论证了直接在压力机的承压板间压缩试件必然导致不均匀的应力分布,即使减少试件端部的摩擦约束也无济于事。本文还证明了在压力机的承压板同试件间插入高径比不小于1.0的刚性垫块就能在试件内获得均匀应力分布。当试件端部接触边界上的切向刚度系数达到10~4kg/cm~3时,试件内轴向应力误差将小于1％,最大径向应力将小于轴向压应力的3％。本文最后给出了实现这一指标的技术途径和部份试验结果。
This paper describes the results of an axisymmetric finite element analysis of the internal stress state of a uniaxially compressed cylindrical rock specimen. The use of a joint element to simulate the contact boundary at the end of the test piece can reflect the relative misalignment of the test piece with the contact material during the deformation process, and therefore the results obtained are more reasonable than those of previous analysis. Second, this paper argues that compressing the specimen directly between the pressure plates of the press will inevitably lead to uneven stress distribution, even if reducing the frictional restraint at the end of the specimen does not help. This paper also proves that inserting a rigid spacer with an aspect ratio of not less than 1.0 between the bearing plate of the press and the test piece can obtain uniform stress distribution in the test piece. When the tangential stiffness coefficient at the end contact edge of the specimen reaches 10~4kg/cm~3, the axial stress error in the specimen will be less than 1%, and the maximum radial stress will be less than 3% of the axial compressive stress. At the end of this paper, the technical approach to achieve this indicator and some test results are given.