地震荷载作用下兰州地铁隧道结构动力响应

根据《兰州轨道交通1号线一期工程地震安全性评价报告》所给出的100年超越概率63%、10%和2%的场地基岩地震加速度时程,利用有限差分软件进行地下隧道硐室的地震反应分析。在模型底部施加基岩地震动,设置监测点监测衬砌结构的弯矩、轴力及剪力随时间的变化过程,得到100年超越概率63%、10%及2%工况下的隧道结构地震响应。结果表明:隧道衬砌结构最大弯矩位于拱顶处,最大轴力位于拱顶和拱底处,最大剪力位于上侧壁或下侧壁处;隧道结构内力随着超越概率的降低而增大;以超越概率63%的结构最大内力为基准值,在超越概率10%和2%时,弯矩分别增大1.2和1.7倍,轴力分别增大1.3和1.5倍,剪力分别增大1.5和2.9倍,增幅最大。这可能预示着隧道结构在强地震动作用下会发生剪切破坏。

Dynamic Response of the Lanzhou Subway Tunnel Structure under Seismic Load

Based on the local site bedrock earthquake acceleration time history for different exceedance probabilities of 63%, 10%, and 2% in 100 a given by The Report of Seismic Safety Evaluation for the First Project of Lanzhou City Rail Transit Line 1, the finite difference method was used to analyze the seismic response of the tunnel cavern. By applying bedrock seismic ground motion to the base of the model and by setting monitoring points to observe the lining structure''s bending moment, axial force, and shear force, the tunnel structure''s seismic response under working conditions at probabilities of exceedance of 63%, 10% and 2% was obtained. The results show that the maximum bending moment of the tunnel lining structure is located in the tunnel vault, the maximum axial forces are located in both the tunnel vault and at the bottom of the tunnel, and the maximum shear force is located in the upper or lower tunnel sidewalls. Tunnel structure''s internal forces were found to increase as the excess probability decreased. Using the structure''s internal forces at the probability of exceedance of 63% as a point of reference, when the excess probabilities were 10% and 2%, the maximum bending moment increased 1.2 and 1.7 times, respectively, the maximum axial force increased 1.3 and 1.5 times, respectively, maximum shear force increased 1.5 and 2.9 times, respectively. This indicates that the tunnel structure could experience shear failure with strong seismic ground motion.