基于声发射RA和AF的玄武岩水—力耦合破裂特征研究

Research on Hydraulic-Mechanical Coupling Fracture Characteristics of Basalt Based on RA and AF Acoustic Emission

以溪洛渡玄武岩为例,开展了水力耦合三轴试验与声发射测试,通过分析张拉占比α随声发射RA和AF比值k的变化规律,提出了一种张拉与剪切裂纹的判定方法,研究了玄武岩内部裂纹的破坏类型及变化规律。结果发现不同水压条件及不同破坏阶段的玄武岩内部裂纹均以剪切破坏裂纹占主导地位,张拉裂纹最大占比仅为9.3%。第Ⅲ、Ⅳ阶段的张拉裂纹占比均随水压增大而增大,而在同一水压条件下,从第Ⅲ阶段到第Ⅳ阶段,张拉裂纹占比呈下降趋势,且随水压增大,下降趋势越显著。这应与有压渗流进入压剪作用下的微裂纹内部产生的一系列影响有关。相关研究对水力耦合作用下岩石裂纹扩展模式和机制的认识具有一定的参考价值。

A hydraulically coupled triaxial test and acoustic emission test were carried out for the basalt of Xiluodu.By analyzing the change law of the tension ratioαwith the ratio k of acoustic emission RA and AF,a method for determining tensile and shear cracks was proposed.The failure type and change law of internal cracks in basalt were study.The results show that the internal cracks in basalt under different water pressure conditions and different failure stages are dominated by shear failure cracks,and the largest proportion of tensile cracks is only 9.3%.The proportion of tension cracks in the third and fourth stages increases with the increase of water pressure.Under the same water pressure,the proportion of tension cracks in the third stage to the fourth stage shows a downward trend,with increase of water pressure,the downward trend becomes more pronounced.This should be related to a series of influences caused by pressurized seepage into the microcracks under the action of compressive shear.Related researches have certain reference value for the understanding of rock crack propagation modes and mechanisms under hydraulic coupling.