为分析软弱围岩隧道在不同开挖方法过程中稳定性以及拱顶沉降变化规律，以某隧道工程实例为背景，借助有限差分软件FLAC3D数值模拟并和实际监测数据对比分析，研究软弱围岩隧道在CD法和台阶法两种不同开挖方法施工过程中围岩变形、应力变化和围岩塑性区分布规律。实际监测数据和模拟计算结果均表明，采用CD法开挖断面关键点位移和应力明显小于台阶法，随开挖步影响范围也比台阶法要小。总之CD法较台阶法能更好控制围岩变形和应力发展，塑性区分布范围也明显小于台阶法。%Aiming at the analysis of the stability and the changing rule of the crown settlement in weak surrounding rock with different tunneling methods, the paper, with reference to a tunnel engineering case,analyzes rock deformation, stress variation and rock plastic zone distribution by means of the numerical simulation of finite difference software FLAC3D and the comparison with the actual monitoring data during the construction by two different excavation methods-CD method and benching method. The actual monitoring data and simulation results show that the cross-section key point displacement and the stress by CD method are less obviously than those by benching method and the same is true with the affecting range. In a word, CD method can better control rock deformation and stress development compared with benching method and the plastic zone distribution range of CD method is also small.
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