Mechanical Properties and Failure Characteristics of Granite Intersected with Single Fractures Under Uniaxial Compression
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摘要:
为研究含贯通单裂隙花岗岩的力学特性及破坏特征,以我国高放废物地质处置甘肃北山预选区完整花岗岩及含倾角30°、45° 和60° 贯通裂隙的花岗岩为研究对象,开展单轴压缩试验研究. 结果表明:裂隙倾角越大,试样的单轴抗压强度、损伤应力以及弹性模量越低;与完整岩石相比,倾角30°、45° 和60° 裂隙花岗岩的抗压强度分别下降7.97%、29.17%和71.68%,损伤应力分别下降9.35%、24.26%和69.79%,弹性模量分别下降5.89%、23.32%和60.49%. 裂隙倾角不同,试样的应力-应变曲线呈现出显著的差别;裂隙倾角越大,损伤应力至峰值应力之间的屈服阶段越明显,发生沿裂隙面滑移破坏特征越显著;裂隙倾角影响花岗岩的破坏模式,试样的破坏形式主要表现为穿裂隙面破坏(倾角30°)、穿裂隙面破坏和沿裂隙面滑移并存的复合破坏(倾角45°)以及沿裂隙面滑移破坏(倾角60°);倾角60° 的裂隙花岗岩的抗压强度与试验前后裂隙面的分形维数差符合幂函数增长关系.
Abstract:To investigate the mechanical properties and failure characteristics of granite intersected with single fractures, uniaxial compression tests were carried out on intact granite and granite intersected with fractures at inclined angles of 30°, 45°, and 60°, which were selected from the Beishan area for geological disposal of highly radioactive waste in Gansu Province of China. The results show that as the inclined angle of the fracture increases, the uniaxial compressive strength, damage stress, and elastic modulus of the specimens decrease. Compared with intact granite, the uniaxial compressive strength of fractured granite at inclined angles of 30°, 45°, and 60° decrease by 7.97%, 29.17%, and 71.68%, respectively, while the damage stress decreases by 9.35%, 24.26%, and 69.79%, respectively. In addition, the elastic modulus of the specimens decreases by 5.89%, 23.32%, and 60.49%, respectively. The stress–strain curves of the specimens show significant differences when the inclined angles of the fractures are different. The larger inclined angle of the fractures indicates a more obvious yield stage between the damage stress and the peak stress, representing more obvious slip failure characteristics along the fracture surface. The inclined angle of the fractures influences the failure mode of granite. The failure modes of the specimens can be divided into three types: failure with fractures intersecting the fracture surface (inclined angle of 30°), slip failure along the fracture surface (inclined angle of 60°), and the compound failure of the first two forms (inclined angle of 45°). Furthermore, the compressive strength of fractured granite at a inclined angle of 60° shows a power function growth relationship with the difference in fractal dimension of the fracture surface before and after the test.
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