中部锁固岩桥三轴加卸荷力学特性及裂纹扩展研究

发布时间：2018-11-16 19:45

【摘要】：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。
[Abstract]:The failure mechanism of rock bridge in the locked high steep rock slope is complex. It is important to study the failure law of the locked section in the middle of the slope and the failure mechanism of the whole deformation of the slope. In order to characterize the fracture at the back edge of the landslide and the creeping failure of the leading edge, the prefabricated cracks at the end of the intact rock sample formed the middle rock bridge. The triaxial loading and triaxial loading tests were carried out for the specimens of three kinds of rock bridges of different lengths. The stress and strain characteristics, strength characteristics and crack propagation modes under two stress paths are analyzed, and the mechanism of crack growth is revealed from the point of view of fracture mechanics. The results show that with the increase of confining pressure and the length of rock bridge, the peak strength and the corresponding strain of the specimen increase, and the peak value and strain of triaxial loading are larger than that of triaxial loading. The stress-strain curve shows the phenomenon of "sudden failure" and "rise after peak", and some samples also show "double peak" characteristics. The rock bridge specimen shows five kinds of crack propagation modes: through the rock bridge, through the top end face of the specimen, to the outer circumferential failure, to the inner circumferential failure and to the bottom end surface of the perforated specimen. Tensile crack and shear crack are produced at the stress concentration of the lower joint tip of the rock bridge specimen, and most of the crack initiation angles are in the range of 40 掳~ 50 掳. The triaxial loading and unloading mechanical tests of the middle rock bridge show that the locking section of the slope is not a single shear failure, but may present a successive multistage failure mode. The crack propagation and failure mechanism of the rock bridge obtained in this study is obtained. It can provide theoretical support for the failure mechanism and deformation characteristics of rock slope excavation and unloading.
【作者单位】：成都理工大学地质灾害防治与地质环境保护国家重点实验室;
【基金】：国家自然科学基金资助项目(41572283,41521002,41130745)~~
【分类号】：TU45

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