中文摘要：

以福州地铁一号线罗汉山站—福州火车站区间隧道为依托工程,对盾构隧道下穿铁路轨道群引起的路基沉降进行了三维有限元数值模拟分析。结果表明：（1）隧道盾构施工过程中,拱肩处塑性变形最为明显,轨道线正下方路基的最大沉降值出现在隧道正上方。双线开挖最大沉降值大于单独开挖隧道一侧所产生的最大沉降值,增长量在8.2%-10.1%之间。隧道开挖结束后,塑性范围仅分布在隧道上部周围土体中,高度约为6.2m,即约1倍隧道直径。（2）盾构掘进对工作面前方土体的影响范围在20 m内,对后方土体的影响范围在30 m内,总体影响范围约为隧道直径的6倍。对后方30m处影响达到最大累积沉降量;对前方20m开外（含20m）沉降几乎无影响。左、右隧道正上方地表的最大沉降值均出现在隧道中间正上方位置。（3）路基沉降监测值与计算结果虽存在一定差距,但整体规律基本一致。

英文摘要：

Based on an interval tunnel between Luohanshan Station and Fuzhou Station in First Line of Fuzhou Metro System as a backing engineering,a 3Dfinite element numerical simulation analysis was conducted on the subgrade settlement occurred by the railway track group passed through underneath of the shield tunnel.The results showed that（1） during the shield construction process of the tunnel,a plastic deformation at the arch spandrel was obvious and a max settlement value of the subgrade right under the rail line was appeared at the right above the tunnel.A max settlement value of the double track railway tunnel excavation would be higher than the max settlement value occurred at one side of the single excavated tunnel and the increased value would be between 8.2%-10.1%.After the excavation operation of the tunnel completed,the plastic scope only was distributed in the soil around the top of the tunnel and the height was about 6.2mand was about 1times of the tunnel diameter.（2）The shield tunneling would have a influence scope within 20 min the front soil of the tunneling face,would have a influence scope within 30 min the rear soil of the tunnel face and the general influence scopewould be about 6times than the tunnel diameter.At the 30 mof the rear part,the influence would reach a max accumulated settlement value.In the front of 20 m,there would be almost no influence of the settlement.The max settlement value of the surface ground just right above the left and right tunnels would appear the right top location of the tunnel center.（3）There was a certain difference between the settlement monitored and measured value of the subgrade and the calculated results and the completed law was the same basically.