岩石巴西圆盘试验中的空间拉应力分布

Spatial distribution of tensile stress in Brazilian disk test of rock

指出目前人们使用了40多年的岩石巴西圆盘试验拉伸强度公式来自二维弹性力学解答,该公式不适用于实际情况所对应的三维弹性力学问题。为了得到三维条件下试样内部的应力分布规律,采用三维有限元分析软件Marc对试样进行了弹性受力分析,结果表明,试样横截面上的拉应力分布规律与二维条件下的情况相类似,但横截面上的应力值沿试样厚度方向是有变化的,越靠近两端面,水平拉应力越大。分析发现,对于高径比为1、泊松比为0.25的巴西圆盘试样,按二维公式计算的抗拉强度比真实值小23.3%。

The authors pointed out that the formula existed for more than 40 years to calculate the tensile strength of rock in Brazilian test is based on 2D elastic theory; and the formula is not suitable for the practical condition which is a 3D problem. In order to obtain 3D stress distribution within the specimen, we adopted software package Marc to carry out a 3D finite element analysis. It is found that the tensile stress distribution at a cross-section of a solid specimen is similar to that of 2D disk. However, the tensile stress at a cross-section varies with the thickness of the specimen. The nearer the cross-section closes to the end of the specimen, the higher the horizontal tensile stress is. When the height-to-diameter ratio of the specimen is 1 and Poisson＇s ratio is 0.25, the tensile strength calculated by the classical 2D solution is 23.3% less than the real value.