凌海花岗岩变形特点与脆性评价

以凌海花岗岩为研究对象，进行了一系列常规三轴高压试验，研究了花岗岩的变形特点及脆性演化规律。基于试验结果，分析了不同围压下的全应力-应变曲线，探讨了静态应变采集试验中花岗岩表面变形特点、峰前损伤规律及其与裂隙扩展的关系，总结了动态采集试验中典型的裂纹扩展模式，并基于改进的峰后能量平衡法评价岩石的脆性。研究结果表明：多应变片静态采集三轴试验中岩样不同位置变形规律差异明显，压缩应变较大的区域往往是裂隙产生、扩展的位置；动态应变采集三轴试验中识别了3种典型的裂隙扩展模式，且与应力加载方式存在一定联系；在70 MPa围压范围内，岩样都表现出明显的脆性破坏特征，其脆性指数随围压增加呈现出先减小后增加再减小的变化趋势。该研究成果对进一步开展其他硬岩的变形破坏机制研究和地下工程的稳定性分析具有一定参考价值。

Deformation behaviour and brittleness of Linghai granite

To investigate the deformation behaviour and the brittleness evolution characteristics of Linghai granite, a series of conventional triaxial compression tests was performed. Complete stress-strain curves under various confining pressures were analyzed in detail. The relation among the specimen surface deformation, damage law and microcrack propagation was discussed on the basis of static strain measurement data. Typical microcracking modes were captured dynamically. Based on the improved post-peak energy method, the brittleness of Linghai granite under triaxial loading conditions was evaluated. The results indicate that there are localised deformations that correspond to the positions of crack initiation and propagation, which are revealed from the multiple long strain gauges showing larger compressive strains in the strain-time curves. Several microcrack propagation modes at the post-peak failure stage, which are related to the stress-controlled loading type to some extent, are observed from dynamic strain monitoring results. Brittle failure of Linghai granite is observed at the confining pressure up to 70 MPa. As the confining pressures increase, the brittleness of the rock decreases initially, and then increases and finally decreases. Experimental results provide an insight into the study of rock failure mechanism and are useful for stability analysis of underground engineering structures.