水平层理棱柱形灰岩抗压强度尺寸效应

Compressive Strength Size Effect of Horizontal Layered Prismatic Limestone

为研究得到棱柱形含水平层理岩石试样与标准圆柱形岩石试样在单轴压缩试验下物理力学性质变化规律及破坏形态之差别,制备9组不同高径比棱柱形灰岩试样进行室内单轴压缩试验,并基于灰色理论GM(1,1)模型对试验数据进行拟合。研究表明:水平层理棱柱形岩石试样破坏过程与圆柱形岩石试样破坏过程基本相同但破坏形式存在差异;当高径比小于2∶1时抗压强度、弹性模量随高径比的减小而减小,泊松比、峰值应变随高径比的减小而增大,破坏形式从简单的对顶锥型劈裂发展到对顶锥型劈裂+沿层面拉裂破坏;相反高径比大于2∶1时抗压强度、峰值应变随高径比的增大而显著减小,而弹性模量、泊松比减小微弱且破坏形式主要为贯通试样的劈裂破坏;研究结果可为非标准形试样及岩石加筋材料工程试验抗压强度换算提供依据。

In order to study the variation of physical and mechanical properties and the difference of failure modes between prismatic rock specimens with horizontal bedding and standard cylindrical rock specimens under uniaxial compression test,nine groups of prismatic limestone specimens with different aspect ratios were prepared for uniaxial compression test in laboratory,and the experimental data were fitted based on the grey theory GM( 1,1)model. The results show that the failure process of prismatic rock specimens with horizontal bedding is basically the same as that of cylindrical rock specimens,but the failure modes are different. When the aspect ratio is less than2∶ 1,the compressive strength and modulus of elasticity decrease with the decrease of aspect ratio,while Poisson’s ratio and peak strain increase with the decrease of aspect ratio. The failure mode develops from simple top-cone splitting to top-cone splitting + pull-out along the plane. On the contrary,when the aspect ratios is larger than 2∶ 1,the compressive strength and peak strain decrease significantly with the increase of aspect ratio,while the elastic modulus and Poisson’s ratio decrease slightly,and the main failure mode is the splitting failure of through specimens. The research results can provide a basis for converting the compressive strength of non-standard specimens and rock reinforced materials in engineering tests.