单轴压缩荷载下红砂岩不同张开度三维通透裂隙扩展机理研究

Propagation mechanism of 3D through fracture with different width under uniaxial load

采用自制的模具在圆柱体红砂岩标准试件上分别加工了不同张开度的通透裂隙,通过单轴压缩试验和数值模拟的方法,系统分析了不同张开度条件下岩石裂隙的扩展机理。试验结果显示,含裂隙试件的峰值强度、起裂强度以及弹性模量等力学参数随裂隙张开度的增大均呈线性减小的趋势,其中峰值强度的变化幅度较小,而起裂强度与弹性模量受裂隙张开度变化的影响较明显;不同张开度裂隙的初始起裂均在裂尖位置以翼裂纹的形式展开,扩展至峰值状态前后,受张开度的影响出现了明显差异。数值模拟结果显示,加载过程中裂隙尖端拉应力集中区域随裂隙张开度的增大逐渐增大,但始终未到达试件边界,而剪应力集中的范围比较稳定基本不随裂隙张开度的变化而改变。

The uniaxial compression test and numerical simulation are employed to systematically analyze through fractures with different widths processed by homemade mold on standard specimens. Test and numerical results are obtained as follows：mechanical parameters such as peak strength, splitting strength and elasticity modulus of specimens with fractures show a liner decrease trend with the enlarge of frac- ture apertures, change of fracture apertures has small effect on peak strength and it has obvious effect on splitting strength and elasticity modulus ; fractures with different widths start at crack-tip and extend in the form of wing cracks, and there has an obvious difference affected by width when it extends before and after peak state;during the load process, tensile stress concentration area at crack tips would enlarge along with the enlarge of fracture apertures, but never reach the specimen border, and the range of shear stress concentration is relatively stable, which would not change along with the change of fracture apertures.