贯通型标准JRC双节理剪切力学及声发射特性研究

Shear mechanics and acoustic emission characteristics of penetrating standard JRC double joints

节理岩体的抗剪性能是影响工程岩体强度及稳定性的关键因素。基于3D打印技术制作标准JRC节理面模具和固定夹板,采取一体化浇筑方式制备不同节理面间距和不同粗糙度的双节理试样,结合声发射(acousticemission,AE)技术探究不同法向应力条件下粗糙双节理岩体剪切力学特性和破坏演化特征。结果表明:剪切应力-剪切位移曲线形态受节理粗糙度和法向应力共同影响。随JRC和法向应力的增加,剪切应力软化程度加重;法向应力较大时,峰后阶段剪切应力存在多次突降现象,突降值随法向应力的增加而增大。峰值剪切强度出现在双节理间岩石夹层断裂时刻,随JRC和法向应力的增加呈增大趋势,随节理面间距增加呈减小趋势。AE结果表明:岩石夹层断裂时刻AE能量大幅突增,AE能量峰值稍滞后于剪切应力峰值,随法向应力的增加,AE能量峰值和累积AE能量值增大;AE定位点空间上集中于岩石夹层部分,时间上频发于200~600 s内,随节理面间距的增加,AE定位点的集中范围扩大。

The anti-shear performance of rock joints is a significant factor that affects the strength and stability of engineering rock mass.In this study,the standard joint surface mold and fixed splints are produced based on the 3D printing technology,and the double-joint specimens with different joint spacings and roughnesses are prepared by adopting the integrated pouring method,and then the acoustic emission technology is combined to explore the shear mechanical properties and failure evolution characteristics of the rough double-joint rock mass under different normal stress conditions.The results indicate that the patterns of shear stress displacement curves are affected by the joint roughness and normal stress.With the increase of the JRC and normal stress,the degree of softening of the shear stress increases;when the normal stress is larger,there are multiple sudden drops in the shear stress at the post-peak stage,and the sudden descending value increases with the normal stress.The peak shear intensity appeares at the fracture of the rock sandwich between two joints,showing an increasing trend with the increase of the JRC and normal stress and decreasing with the increase of the joint spacing.The AE results show that the AE energy increases sharply at the fracture moment of the interlayer,and the peak value of AE energy slightly lags behind the peak value of shear stress.With the increase of the normal stress,the peak value of AE energy and the cumulative AE energy value increase.The AE positioning points are concentrated in the rock interlayer,occurring frequently within the range of 200~600 s,and with the increase of the joint spacing,the concentration range of the AE positioning point expands.