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根据大变形锚杆的力学和变形特性,建立大变形锚杆–围岩相互作用结构模型,研究锚杆加固圆形隧道时的支护效应,并通过数值模拟验证了模型和求解方法的有效性。采用上述求解方法,定量分析了原岩应力、岩体强度以及大变形锚杆安装密度、长度和安装时间对其支护效果的影响规律。结果表明,在高应力或极软岩等恶劣地质条件下,围岩产生较大位移的情况下,大变形锚杆可以更好的发挥支护效应。大变形锚杆加固的主要作用在于限制塑性区围岩的变形,对塑性区边界的位置以及弹性区岩体变形的控制效果不明显。还通过改变安装锚杆时等效内支撑力的大小,揭示了锚杆安装时间对其支护效应的影响规律。研究结果可为大变形锚杆支护设计及参数优化提供基础理论依据。
According to the mechanics and deformation characteristics of the large deformation anchor rod, the interaction model between the large deformation anchor rod and the surrounding rock is established to study the support effect when the circular tunnel is reinforced with bolts. The effectiveness of the model and the solution method are verified by numerical simulation . The influence of the original rock stress, the strength of rock mass and the installation density, length and installation time of the large deformation bolt on the supporting effect are quantitatively analyzed by the above solving method. The results show that under the condition of high stress or extremely soft rock and other harsh geological conditions, the large deformation of the rock bolt can play a better supporting effect under the condition of large displacement of surrounding rock. The main function of the large deformation anchor reinforcement is to limit the deformation of surrounding rock in the plastic zone and to control the position of the plastic zone boundary and the deformation of the rock mass in the elastic zone is not obvious. By changing the equivalent internal support force when installing anchor, the influence law of anchor support time on its support effect is revealed. The research results can provide the basic theory basis for the design of large deformation bolt support and parameter optimization.