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锁固型高陡岩质边坡内部岩桥破坏机制复杂,研究边坡中部锁固段的破坏规律及其对边坡整体变形破坏机制具有重要意义。为表征滑坡后缘拉裂缝和前缘蠕滑破坏,在完整岩样端部预制裂纹形成中部岩桥,开展3种不同长度岩桥试样的三轴加载和三轴加卸荷试验,分析2种应力路径下的应力–应变特征、强度特征和裂纹扩展模式,从断裂力学角度揭示了裂纹扩展机制。结果表明:随围压和岩桥长度的增加,试样峰值强度和对应的应变增大,且三轴加卸荷峰值和应变均大于三轴加载;应力–应变曲线呈现出“突发式破坏”和“峰后回升”现象,部分试样还表现出“双峰值”特征;岩桥试样呈现贯通岩桥、贯通试样上端面、向外环向破坏、向内环向破坏及贯通试样下端面等5类裂纹扩展模式;岩桥试样在下部节理尖端应力集中处产生张拉裂纹和剪切裂纹,大部分裂纹起裂角集中在40°~50°范围。中部岩桥三轴加卸载力学试验表明,边坡锁固段并非一次剪断破坏,可能呈现逐次多级破坏模式,本研究获得的岩桥裂纹扩展及破坏机制,可为锁固型岩质边坡开挖卸荷的破坏机制和变形特征提供理论支撑。
The failure mechanism of the rock bridge inside the locked high-steep rock slope is complicated, and it is of great significance to study the failure regularity of the locked section in the middle of the slope and its effect on the overall deformation and failure mechanism of the slope. To characterize the landslide trailing edge of the crack and the front edge of the creep rupture, the integrity of the rock specimen at the end of the central prefabricated rock bridge to carry out three different lengths of rock bridge specimen triaxial loading and triaxial unloading test, analysis 2 Stress-strain characteristics, strength characteristics and crack propagation modes under different kinds of stress paths, the mechanism of crack propagation is revealed from the point of view of fracture mechanics. The results show that with the increase of confining pressure and rock bridge length, the peak strength and corresponding strain increase, and the peak value and strain of triaxial unloading and unloading are larger than that of triaxial loading. The stress-strain curve shows a “ Some samples also showed the characteristic of ”double peak". The rock bridge specimen showed through the rock bridge, penetrated the upper end surface of the sample, outwardly and outwardly damaged, inward Ring fracture and penetrate the lower end of the specimen 5 types of crack growth mode; rock bridge specimen in the lower tip of the stress concentration stress cracks generated at the site and shear cracks, most of the crack initiation angle concentrated in the 40 ° ~ 50 ° range . The uniaxial loading and unloading tests show that the locked section of the slope is not a single shear failure and may show a successive multi-stage failure mode. The crack propagation and failure mechanism of the bridge in this study can be used for the locking rock slope Excavation unloading damage mechanism and deformation characteristics provide theoretical support.