颗粒尺寸对岩石抗拉强度和断裂韧度影响的数值模拟

选取三种粒径(平均尺寸1.02,2.12,3 mm)花岗岩试样,利用自主开发的岩石破裂过程数值计算软件(RFPA-DIP细观版),进行带缺口试样三点弯曲试验.利用虚裂纹模型描述岩石试样达到峰值载荷前的断裂过程区,引入双线性应力分布模型,将试样内部平均颗粒尺寸与虚裂纹模型建立起联系,通过数值模拟可分别计算出不同颗粒尺寸花岗岩的抗拉强度和断裂韧度.通过引入分形维数概念来表达不同颗粒尺寸花岗岩试样内部颗粒分布的特征,得到结论:颗粒尺寸与分维值呈反比例关系,分维值较小的花岗岩试样其抗拉强度和断裂韧度相对较小.

Numerical Simulation for Calculating the Tensile Strength and Fracture Toughness Based on Different Grain Sizes

Three-point-bending tests on three kinds rock samples of grain sizes 1.02mm(fine grained)， 2.12mm (medium grained) and 3mm(coarse grained) with different notches are numerically performed by RFPA-DIP version to simulate the failure process compared with experimental results in laboratory. A simple fracture model is established， linking fictitious crack to the average aggregate size so that the rock specimen and fictitious crack formation can be considered together. Maximum loads of three-bending-point tests with different initial notches containing different tensile strength and fracture toughness are analyzed. The concept of fractal dimension is introduced to characterize the grain size distribution. It is concluded that the fractal dimension decreases with the increase of grain size， and the rock samples with smaller fractal dimension correspondingly have smaller tensile strength and fracture toughness.