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本文叙述了用三点弯曲方法对大理岩、石灰岩、花岗片麻岩等五种岩石试件断裂韧度K_(IC)值的测定工作。指出了测定工作中岩石材料和金属材料表现出的不同特点。对其中临界荷载的选取、有无疲劳裂纹的差别以及裂纹长度和宽度的影响等进行了实验研究和理论分析。文中提出:由于岩石结构弱面的影响,有、无疲劳裂纹的试件的裂纹扩展机理不同,因而K_(IC)值有明显差别;随着裂纹宽度由0.02增至0.3毫米,其K_(IC)值反而下降;岩石的K_(IC)值与劈裂法测得的抗拉强度值线性相关。最后对岩石采用三点弯曲方法提出了一些建议。
This paper describes the determination of the fracture toughness K_(IC) values of five kinds of rock specimens such as marble, limestone and granite gneiss using the three-point bending method. Points out the different characteristics of rock materials and metal materials in the measurement work. The experimental research and theoretical analysis were carried out on the selection of critical load, the difference in the presence or absence of fatigue cracks, and the influence of crack length and width. The paper proposes that due to the influence of the weak surface of the rock structure, the crack propagation mechanisms of the specimens with and without fatigue cracks are different, and thus the K_(IC) values are significantly different; as the crack width increases from 0.02 to 0.3 mm, the K_(IC) The value of K(IC) decreases linearly with the measured tensile strength value of the splitting method. Finally, some suggestions on the three-point bending method for rock are put forward.