基于尺寸效应的红砂岩点荷载强度试验研究

Experimental Study on Point Load Strength of Red Sandstone Based on Size Effect

以云南武定南华采石场的红砂岩为研究对象,制备不同尺寸的岩心样,利用自行研制的便携式点荷载仪进行点荷载轴向试验、径向试验,并结合单轴压缩试验,分析尺寸效应对规则岩心样点荷载强度的影响以及点荷载强度与单轴抗压强度的关系。试验结果表明:点荷载强度具有明显的尺寸效应,在不同试验方式下,试件直径和厚度对点荷载强度值的影响不同;分析了形状系数与点荷载强度的关系,并提出不同试验方式下形状系数的建议取值范围;获得云南武定地区红砂岩点荷载强度和单轴抗压强度之间的经验转换公式,以期为该地区的工程应用提供参考。

Taking the red sandstone of Nanhua quarry in Wuding County, Yunnan Province as the research object, the core samples with different sizes were prepared. The point load axial tests and radial tests were carried out by using the self-developed portable point load instrument. Combined with the uniaxial compression tests, the influence of size effect on the point load strength of regular core samples was analyzed, as well as the relationship between point load strength and uniaxial compressive strength. The test results show that the point load strength has an obvious size effect, and the influences of diameter and thickness of samples on the point load strength are different under different loading modes. The relationship between shape coefficient and point load strength was analyzed, and the recommended value range of shape coefficient under different loading modes was put forward. The empirical conversion formulas of point load strength and uniaxial compressive strength of red sandstone in this area were obtained, so as to provide a reference for engineering application in this area.