The fracture behaviour of layered rocks is strongly influenced by bedding planes, which usually have lower strength than rock matrix. In this study, experimental and numerical fracture toughness tests were conducted on cracked straight through Brazilian disc (CSTBD) specimens with a prefabricated crack to study the bedding plane properties on the fracture behaviour. Experimental studies were mainly focused on the influence of the bedding plane-loading angle on the fracture load, fracture toughness and fracture pattern. With increasing bedding plane-loading angle, the fracture load continuously increased, the main crack initiation position transformed from the prefabricated crack tip to a certain distance from the prefabricated crack tip, Mode I and effective fracture toughness continuously decreased, and Mode II fracture toughness first increased and then decreased when the prefabricated crack was parallel to the bedding plane. When the prefabricated crack was perpendicular to the bedding plane, the fracture load increased as a whole, the main crack initiation position transformed from a certain distance from the prefabricated crack tip to the prefabricated crack tip, the Mode I fracture toughness first slightly decreased and then continuously increased, the Mode II fracture toughness first increased and then decreased, and the effective fracture toughness increased as a whole with increasing bedding plane-loading angle. A numerical model based on cohesive elements was developed to reveal how the bedding plane strength primarily influences the fracture pattern, and the percentage of shear cracks and tensile cracks. When the prefabricated crack was parallel to the bedding plane, the main crack type was identical under each bedding plane strength. When the prefabricated crack was perpendicular to the bedding plane, the main crack initiation position transformed to the prefabricated crack tip with increasing bedding plane strength. With increasing bedding plane strength, the percentage of shear cracks decreased, and the corresponding percentage of tensile cracks increased as a whole for both position relations.

层状岩石的断裂行为受到层理面的强烈影响，层理面通常比岩石基体的强度低。在这项研究中，对带有预制裂纹的直通巴西圆盘​​（CSTBD）试样进行了实验和数值断裂韧性测试，以研究层理平面特性对断裂行为的影响。实验研究主要集中在层理平面加载角对断裂载荷，断裂韧性和断裂模式的影响上。随着垫层平面载荷角的增大，断裂载荷不断增大，主裂纹起始位置从预制裂纹尖端向预制裂纹尖端转变一定距离，I型和有效断裂韧性不断降低，当预制裂纹平行于层理平面时，II型断裂韧性先增加然后降低。当预制裂纹垂直于顺层平面时，断裂载荷整体上增加，主裂纹起始位置从预制裂纹尖端到预制裂纹尖端的一定距离发生转变，I型断裂韧性首先略微下降，然后下降连续增加，模式II的断裂韧度先增加然后减小，并且有效的断裂韧度总体上随垫层平面加载角的增加而增加。建立了基于粘性元素的数值模型，以揭示层理面强度如何主要影响断裂模式以及剪切裂缝和拉伸裂缝的百分比。当预制裂缝平行于层理平面时，在每个层理平面强度下，主要裂缝类型相同。当预制裂缝垂直于层理平面时，随着层理平面强度的增加，主裂缝起始位置转变为预制裂缝尖端。随着垫层平面强度的增加，两个位置关系中的剪切裂纹百分比均降低，而相应的拉伸裂纹百分比则总体上增加。