石灰岩抗拉强度的试样厚度效应试验研究

Analyzing Size Effect of Limestone Sample's Tensile Strength

岩石的抗拉强度是反映岩石力学性质的一个重要指标,也是矿山工程稳定性分析的重要依据。通过对厚度在25 mm、30 mm、50 mm的圆柱形石灰岩试样进行巴西劈裂试验,采用统计和回归的方法,分析了试样厚度对岩石劈裂强度和拉伸弹性模量的影响。研究结果表明,石灰岩劈裂强度以及拉伸弹性模量均随试样厚度的增加而减小,岩石劈裂时横向应变也受试样厚度的影响,并存在明显的应变尺寸效应。劈裂试验中,岩石试件的拉伸应力-应变曲线呈线性关系,曲线的斜率随着试件厚度增加而减小。岩石破坏形态主要沿加载直径劈裂破坏为两个半圆,且两加载端基本完整,试件的破坏面一般都是沿着轴向受载荷的方向。

In order to study the size effect caused by different splitting strength and tensile elastic modulus of the thickness rock sample, brazil split test is performed with cylindrical limestone specimens of three different types of rocks. The sample thickness are 25 ram, 30 mm and 50 mm respectively. Splitting strength of the rock is processed by the methods of statistics and regression. The research results show that the splitting strength and the tensile elastic modulus of the Limestone decrease with increasing sample thickness. The lateral strain is affected by the sample thickness during the rock cleavage with obvious size strain effect. In addition, the stress - strain curve and its failure pattern were analyzed. The curve apparently is demonstrated as linear relationship. The rock destruction mainly along the loading diameter splitting failure of two semicircles with integrating two load ends.