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综合采用现场测试及数值计算方法,对深圳市南坪快速II期双洞八车道小净距隧道施工中二衬受力分布规律,以及不同间距下近邻隧道施工后行洞对先行洞二衬结构受力的影响进行研究。研究结果表明:二衬各点轴力和弯矩值均较小;拱顶处、远离中岩柱侧的边墙和中岩柱侧拱脚部位有可能出现较小拉力,应注意防止混凝土开裂;Ⅳ级围岩、30 m净距条件下,后行洞开挖对先行洞支护受力的影响范围为掌子面后方40 m内,围岩越好,影响范围越小;仅拱顶处主应力表现为受拉,其余部位表现为受压,其中左、右拱脚处主应力压力值最大。随着净距的逐渐增大,拉应力与压应力值变化很小,没有一致增大或减小的趋势,净距变化对支护的应力影响不明显。
Based on field test and numerical calculation method, the distribution rule of the second lining force in the construction of the small clear distance tunnel with two lanes and two lanes in Nanping Rapid Shenzhen II tunnel, The impact of stress research. The results show that the axial force and bending moment are small at each point of the two linings. There is a possibility that there will be less tension at the vaults, the side walls away from the middle rock columns and the side arch feet in the middle rock columns, so as to prevent cracking of the concrete ; Ⅳ grade rock, under the condition of 30 m clear distance, the influence scope of the backhole excavation on the force of the first cave support is within 40 m of the back of the face; the better the surrounding rock is, the smaller the influence scope is; The main stress is tensile, while the other parts are under compression, of which the main stress is the largest at the left and right arches. With the gradual increase of the clearance, the tensile stress and compressive stress change little, there is no consistent increase or decrease the trend of net spacing changes on the impact of stress is not obvious.