中文摘要：

通过对3种厚度在20-50mm不等的圆柱形岩石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的影响，得出单轴抗压强度越大的岩石，巴西劈裂强度的尺寸效应越明显；不同岩石劈裂强度的尺寸效应各有不同，白色大理石劈裂强度随试样厚度增加呈线性减小，硅质砂岩劈裂强度随试样厚度增加呈线性增大，炭质泥岩劈裂强度随厚度增加呈指数增大．拟合这3种岩石劈裂强度与厚度关系的函数，相关系数都在0．99以上．试验结果还表明，不同岩石劈裂时横向应变和轴向应变也受试样厚度的影响，存在明显的应变尺寸效应．

英文摘要：

In order to study the size effect caused by different splitting strength of the thickness rock sample, brazil split test is carried out with cylindrical specimens of three different types of rocks, the sample thickness is 20 - 50 cm. Splitting strength of the rock is processed by the methods of statistics and regression, we find that the greater the uniaxial compressive strength of rock is, the more obvious of size effect of brazil splitting strength;The strength size effect of different lithologic rock is different, the splitting strength of white marble is linearly decreases with the increase in the thickness of the samples, the splitting strength of siliceous sandstone is increase linearly with the increase in thickness of the sample, the splitting strength of carbargilite increases exponentially with the increase in thickness of the sample. The function relationships of splitting strength and thickness of the three kinds of rock are fitted, the correlation coefficients are all greater than 0.99. And we found that the transverse strain and axial strain are also affected by the thickness of the samples, there are obvious strain size effects in the splitting test.