地震作用下滨海岛礁吹填砂地层液化规律及隧道动力响应特性

Study on Liquefaction Law of Backfill Sand Stratum in Coastal Island Reef and Tunnel Dynamic Response Characteristics Under Earthquake Action

以厦门地铁3号线工程为依托,通过FLAC 3D软件结合反映混凝土损伤的弹塑性模型建立土-盾构隧道相互作用模型,探究地震作用下吹填砂地层的液化发展规律及盾构隧道动力响应特征。结果表明:在地震荷载作用下,远离盾构隧道处孔隙水压力、有效应力均逐步上升最后趋于稳定,而在盾构隧道附近处有效应力先减小后增大,超孔隙水压力先增大后减小;地震结束时刻管片损伤最大值在拱腰至拱脚之间,但远小于混凝土的破坏限值;地震引起的损伤增量在拱顶与拱底处最小,在拱腰与拱脚附近最大,故拱腰至拱脚处为隧道衬砌结构抗震最不利部分。

Based on the Xiamen Metro Line 3 project,a soil-shield tunnel interaction model was established using FLAC 3D software combined with an elastic-plastic model reflecting concrete damage model.The liquefaction development law of backfill sand stratum under earthquake action and the dynamic response characteristics of shield tunnels were explored.The results show that under seismic loads,the pore water pressure and effective stress at the locations far away from the shield tunnel gradually increase and eventually stabilize,while the effective stress first decreases and then increases near the shield tunnel,and the excess pore water pressure first increases and then decreases.At the end of the earthquake,the maximum damage value of the pipe segment is between the arch waist and the arch foot,however,it is far less than the damage limit of the concrete.The damage increment caused by earthquakes is the smallest at the top and bottom of the arch,and the largest near the waist and foot of the arch.Therefore,the section from the waist to the foot of the arch is the most unfavorable part of the seismic resistance of the tunnel lining structure.