静动载下共面非贯通裂隙贯通机制分析

共面非贯通裂隙的贯通机制对于确定外载下岩质边坡的滑动面位置及滑动面综合抗剪强度至关重要。采用预制共面非贯通裂隙石膏模型试样单轴静动载对比试验，对不同裂隙倾角共面排列裂隙的扩展、贯通过程进行了观测，研究显示：共面非贯通裂隙不同倾角下的贯通模式存在较大差异，裂隙倾角为0o～35o时以裂隙面发生闭合变形为主；45o～65o时裂隙间较易出现剪切型破坏模式；75o～90o预制裂隙面较难产生滑动，裂隙试样主要产生劈裂形式的破坏。动载下预制裂隙试样裂尖翼裂纹及次生共面裂纹起裂后易朝原起裂方向快速发展；易在两预制裂隙内端部产生直接贯通，这与静载下岩桥处的贯通常通过分支裂纹拐折扩展、相连不同。含共面非贯通裂隙试样在裂隙倾角为35o左右时强度呈现最小值，这与贯通性裂隙试样裂隙倾角为60o左右呈现最小值相差较大，这是因为裂隙面摩擦强度没来得及发挥作用所致。因此，含非贯通节理裂隙岩体的综合抗剪强度公式应引入强度发挥系数，以充分考虑岩桥胶结强度与裂隙面摩擦强度不能同步发挥作用的破坏本质。

Analysis of coalescence mechanism of coplanar intermittent flaws under static and dynamic loading

The coalescence mechanism of coplanar intermittent flaws under static and dynamic loading is important in determining the position and shear strength of sliding face of rock slope. The process of the fracture propagation and coalescence between two coplanar intermittent flaws is studied under uniaxial static and dynamic loading. The specimens made of sandstone-like modeling material contain two pre-existing coplanar flaws with different flaw angles from 0o to 90o. The result indicates that the coalescence modes are different for different flaw angles. When the flaw angles are between 0o and 35o, the flaw surfaces produce close deformation mostly; when the flaw angles are between 45o and 65o, the fractures coalesce in shear modes; when the flaw angles are between 75o and 90o, the splitting failures are prone to appear. Moreover, the growth of the wing fracture and secondary co-planar fracture tends to the original propagation direction, and the immediate coalescence is taken place easily between two pre-existing flaws. But the fracture coalescence path is winding under static loading, which is different from dynamic loading. Additionally, the lowest strength is observed when the flaw angle is 35o for specimens containing intermittent flaws, which is different from specimens containing persistent flaws whose lowest strength is observed at 60o. The reason is that the strength of fracture surface is not mobilized when the specimen fails. Because the rock bridge’s strength and fracture surface’s friction can’t be mobilized simultaneously, the shear strength formula for rock mass containing intermittent flaws should introduce a strength mobilization factor.