巴西劈裂法在层状岩体抗拉强度测试中的分析与讨论

为分析巴西圆盘劈裂法在层状岩体抗拉强度试验中的适用性，在以往层状岩体巴西圆盘劈裂试验成果分析基础上，选取层理砂岩为试验对象，设计并进行了考虑不同层理角度的砂岩巴西圆盘劈裂试验。分析结果表明，（1）层状岩体抗拉强度的各向异性特点非常明显，层理角度对各种层状岩体的劈裂抗拉强度的影响规律是基本类似的，只是影响程度不一样；（2）不同层理角度圆盘试样的破裂面形状差别较大，其破坏模式可以归纳为直线型、折线型和弧形型；（3）当层理角度0°＜β＜90°时，破裂面的发展规律不能严格满足巴西圆盘劈裂试验力学理论模型的假定，采用式（1）计算得到的劈裂抗拉强度只能是一个近似的值；（4）当圆盘试样加载线两侧的岩石材料、层理结构对称分布时，加载时圆盘内的应力分布可以较好地满足其理论计算模型，其试验结果比较准确。研究成果可为层状岩体抗拉强度的准确测定提供较好的参考。

Analysis and discussion on Brazilian tests on layered rock tensile strength

In order to analyze the applicability of Brazilian disc splitting method in tensile strength test of layered rock mass, by analyzing Brazilian splitting test results of the layered rock mass, selecting the bedded sandstone as test subjects, a kind of Brazilian disc split test considering sandstones’ different bedding angles has been designed and then carried out. The results show that：(1) The anisotropy of the tensile strength of layered rock is very obvious; and the influence of bedding angle on the splitting tensile strength of layered rock mass is substantially similar, but the degree of influence is different. (2) The difference of different bedding angle disc samples’ fracture surface shape is large; the failure modes can be summarized as linear，bent and arc. (3) When the bedding angle is in the range of 0°＜β＜90°，the development law of rupture surface can not strictly meet the assume of Brazilian splitting test disc mechanics model; the splitting tensile strength calculated by the equation (1) can only be an approximate value. (4) When the rock sample materials and bedding structure are symmetry distributed on both sides of the disc samples` load line, the stress distribution in the disk during the loading process can better satisfy its theoretical calculation model; the test results are more accurate. The research results can provide a good reference for the tensile strength’s accurate determination of the layered rock.