压缩载荷作用下岩石类材料的断裂模式研究

Research on Fracture Mode of Rock-type Materials under Compressive Loading

为了解岩石类材料在压缩条件下的裂纹扩展规律,本文对含有内部倾斜裂纹的石膏板试件进行了双轴压缩实验。研究表明:在通常情况下岩石裂纹按I型张拉模式扩展,但随着裂纹表面摩擦系数μ和围压与纵向荷载比值λ的提高,翼裂纹扩展的偏转角随之减少。当裂纹表面摩擦系数和围压与纵向荷载比值足够大时,例如,μ=0.83和λ=0.315,岩石裂纹按Ⅱ型剪切模式扩展。然而,当裂纹表面摩擦系数和围压与纵向荷载比值进一步增加时,石膏板试件将发生强度破坏。本文提出了一个理论模型用以解释和描述这一实验现象。

In order to understand crack propagation mode in rock-type materials under compression, gypsum plates with inner oblique cracks were tested under biaxial compressive loading. Results show that, in general, a crack propagates in the tension mode Ⅰ. With the increase of friction coefficient μ between the crack surfaces and the increase of the ratio λ between the horizontal load and the vertical load, angle between the wing crack and the main crack decreases. When the friction coefficient and the load ratio are large enough, for example, μ=0.83 and λ=0. 315, the crack will extend in the shear mode Ⅱ. However, when the friction coefficient and the load ratio are increased further, the specimen breaks into pieces due to failure of strength. A theoretical model is proposed in this paper to describe and explain the experimental phenomena.