石英含量及方解石脉倾角对页岩破坏特征影响数值模拟

Numerical Simulation of Effects of Quartz Content and Calcite Vein Dip on Shale Damage Characteristics

应用数值分析软件RFPA2D-DIP对不同石英含量及方解石脉倾角页岩试样在单轴压缩下的力学特征及裂缝扩展规律进行研究,分析了石英含量与方解石脉倾角α对试样抗压强度、应力-应变曲线、破裂模式和分形维数的影响。结果表明,在石英含量相同的情况下,α=0°、α=15°和α=90°时,抗压强度较高;α从15°至30°时,试样的抗压强度大幅降低;当α在30°~75°时,受到的滑移作用较明显,试样的抗压强度较低。α=0°时,试样的抗压强度随着石英含量的增加而增加;但将α增加到30°后,相同倾角下试样的抗压强度随石英含量增加而减小。α=0°、α=15°、α=30°和α=90°的试样破坏模式较为复杂,对应的分形维数较大,便于裂缝在试样中扩展,促进复杂缝网的形成。

RFPA2D-DIP was applied to study the mechanical characteristics and crack extension patterns of shale specimens with different quartz contents and calcite vein inclinations under uniaxial compression,and the effects of calcite vein inclinationαand quartz content on the specimens'compressive strengths,stress-strain curves,rupture modes and fractal dimensions were analysed.The results showed that in the same quartz content,the fracture mode and fractal dimension of the specimens were not affected.The results show that under the same quartz content,the compressive strength is higher whenα=0°,α=15°andα=90°;the compressive strength of the specimens decreases sharply whenαranges from 15°to 30°;when aαranges between 30°and 75°,the slipping effect is more obvious,and the compressive strength of the specimens is lower.α=0°,the compressive strength of the specimens increases with the increase of the quartz content;however,after the increase ofαto 30°,the compressive strength of the specimens under the same inclination angle is lower than that under the same inclination angle.However,after increasingαto 30°,the compressive strength of the specimens with the same inclination angle decreases with the increase of quartz content.α=0°,α=15°,α=30°,andα=90°have more complex damage modes,which correspond to larger fractal dimensions,which facilitates the expansion of cracks and promotes the formation of complex seam networks in the specimens.