Mine-by试验洞开挖过程中围岩应力路径与破坏模式分析

发布时间：2018-11-03 10:30

【摘要】：地下洞室开挖过程中,围岩经历了复杂的应力路径,正确刻画围岩的应力路径及其影响是岩石地下工程中亟待解决的关键科学问题。基于起裂判据(CIC)、扰动应力比(n=σ_3/σ_1)和Lode参数等力学表征指标,采用FLAC~(3D)对Mine-by试验洞掌子面掘进过程中围岩的复杂应力路径和破坏模式进行探讨。研究表明:围岩应力场的扰动主要集中在掌子面前后一倍洞径范围内,围岩损伤受掌子面附近高度集中的偏应力和应力主轴旋转支配;随掌子面掘进,围岩顶部和底部偏应力集中程度加大,应力比n逐渐降低,逐步形成V型剥落,而隧洞边墙部位逐渐卸荷,损伤破裂转变为拉应力控制;原位岩体的应力路径涉及应力主轴旋转效应,远比实验室的单调加载路径复杂,Mine-by试验洞开挖过程中,在掌子面的顶部和底部,围岩大主应力方向几乎没有转动,而中主应力和小主应力旋转一定角度(35.2°)后回到初始方向,由于中主应力超过了岩体起裂强度(CIC1),其方向的旋转加剧了围岩的损伤程度。相关认识和结论具有一定的理论和工程意义。
[Abstract]:During the excavation of underground cavern, the surrounding rock has experienced a complex stress path. It is a key scientific problem to be solved in underground rock engineering to correctly depict the stress path of surrounding rock and its influence. Based on the mechanical characterizations of (CIC), disturbance stress ratio (n = 蟽 _ 3 / 蟽 _ 1) and Lode parameters, the complex stress paths and failure modes of surrounding rock in the driving process of Mine-by test tunnel face are discussed by FLAC~ (3D). The results show that the disturbance of surrounding rock stress field is mainly in the range of double diameter of tunnel before and after the face of the face, and the damage of surrounding rock is dominated by the highly concentrated deflection stress and the rotation of the principal axis of stress near the face of the palm. With the excavation of the face, the degree of stress concentration at the top and bottom of the surrounding rock increases, the stress ratio n decreases gradually, and the V type spalling is gradually formed, while the side wall of the tunnel gradually unloads, and the damage and rupture change to the control of tensile stress. The stress path of in-situ rock mass involves the rotation effect of stress spindle, which is much more complicated than the monotone loading path in laboratory. During the excavation of Mine-by test cave, the direction of large principal stress of surrounding rock almost does not rotate in the top and bottom of the face. However, the medium principal stress and small principal stress rotate at a certain angle (35.2 掳) and then return to the initial direction. Because the middle principal stress exceeds the fracture initiation strength (CIC1) of the rock mass, the rotation of the middle principal stress direction intensifies the damage degree of the surrounding rock. The related knowledge and conclusion have certain theoretical and engineering significance.
【作者单位】：中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室;中国科学院大学;长江勘测规划设计研究院;
【基金】：国家重点基础研究发展计划(973)项目(2015CB057905) NSFC 云南联合基金重点支持项目(U1402231)) 国家自然科学基金资助项目(51279202)~~
【分类号】：TU45

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