中文摘要：

研究了集中加载、加载板加载和平台加载3种不同加载方式对巴西圆盘的宏观力学行为、开裂过程以及材料的抗拉强度的影响。对于平台加载方式给出了不同平台加载角时抗拉强度的修正系数。在数值模拟中，采用了自主开发的连续-非连续方法，该方法将拉格朗日元、变形体离散元及虚拟裂纹模型耦合在一起，既可以很好地模拟弹性阶段的变形，又可以较好地模拟材料的真实开裂过程。研究发现，采用平台加载方式，有利于圆盘中心起裂，而采用集中加载和加载板加载方式，圆盘的加载部位容易发生剪破坏。在圆盘中心起裂时，集中加载方式的抗拉强度的数值解最接近于选取的抗拉强度，然后是加载板加载方式，最后是平台加载方式。无论对于哪种加载方式，在材料的抗拉强度较小时，圆盘易于中心起裂，否则圆盘的加载部位将发生剪破坏。圆盘中心起裂后，众多微裂纹汇聚成的裂纹带在垂直方向不断扩展，直至贯穿整个圆盘，同时伴有应力波产生并传播。

英文摘要：

Effects of three types of loading, i.e. concentrated loading, plate loading and flattened loading, on the macroscopically mechanical behaviors, tensile strength and cracking processes of Brazilian disks are numerically investigated. The effect of tensile strengths of materials is presented for three kinds of loading types. In addition, the modified coefficients of tensile strength at different loading angles are presented for the flattened Brazilian discs. A continuum-discontinuum method which combines the Lagrangian element method, the deformational discrete element method and the fictitious crack model is adopted. The method can be used to simulate the deformation in the elastic stage and actual cracking of materials. It is found that the flattened loading easily leads to a crack at the center of Brazilian disc, while the concentrated loading or plate loading most likely results in shear failure. When the disk failures at the center, the numerical solution of the concentrated loading is closest to the calculated tensile strength, followed by the plate loading mode, and finally the flattened loading. The materials with low tensile strength normally leads to cracking at the center of the disk for any loading type; otherwise, there is shear failure at two loading ends of the disc. After the disk centrally cracks, a great number of microeracks coalesce to form a band that continuously propagates along the loading direction, and meanwhile the failure is accompanied by stress wave generation and propagation.