三轴试验下结构面倾角对制备岩样力学特性的影响

结构面倾角对岩样的力学特性有很大影响。人工制备了结构面倾角为15°、30°、45°、60°（水平面为0°面）的单贯通结构面岩样和完整样，并进行了单轴压缩试验和围压为100、200、300 kPa的三轴压缩试验来探讨结构面倾角对其力学和变形特性的影响。试验结果表明：①当倾角小于等于30°时，出现了岩样应力-应变曲线中典型的4个阶段。而当倾角等于45°和60°时，最后阶段变为先软化再硬化的特征；②结构面岩样均先体缩再体胀。随着围压增加，体缩最大值接近，而体胀呈明显减小趋势。随结构面倾角增加，体缩呈缓慢增长趋势，并在30°和45°时出现体缩突变。而体胀显著的减小。最后，指出了耶格尔单结构面判据的不足，并对其进行了修正，验证结果表明改进的耶格尔判据与试验结果吻合较好。

Influence of dip angle of structural planes on mechanical properties of artificial rock samples under triaxial test conditions

The dip angle of structural plane has great influences on mechanical properties of rock samples. In this study, the rock samples with structural planes of 15°, 30°, 45°, 60° (the structural plane of 0° is along the horizontal direction)and the intact rock samples are prepared. Uniaxial tests and triaxial tests with confining pressures of 100 kPa, 200 kPa and 300 kPa are performed to investigate the influence of dip angle of structural planes on their mechanical and deformation features. Test results demonstrate that: 1) the stress-strain curve exhibits the four typical stages, which are similar to those of rock samples when the dip angle is no more than 30°, but the last phase exhibits the characteristics of softening followed by hardening when the dip angle is equal to 45°or 60°, 2) for all the samples, the contractive volumetric strain is firstly shown, and then the dilative volumetric strain is followed. With the increasing confining pressure, the maximum value of contractive volumetric strain does not change much, but the dilative volumetric strain obviously decreases. With the increase of the dip angle, the contractive volumetric strain slowly increases, and the contractive volumetric strain suddenly changes when the dip angle increases from 30°to 45°. However, the dilative volumetric strain obviously decreases. Finally, the disadvantage of Jaeger’s single structural plane criterion is pointed out, and thus the criterion has been improved. The verification results denote that the improved Jaeger criterion is in good agreement with the experimental results.