With the 4th section of Malian shield tunnel on Guangzhou Metro Line 9 as an example, the land subsidence law caused by the adjacent construction of parallel shield tunnel is analyzed by using Plaxis 3D Tunnel finite element analysis software. The results show that the land subsidence is normally distributed and the horizontal displacement is distributed in a "butterfly pattern" when the right line passes alone; in the case of double lines, the distribution of the land subsidence is in a "W" pattern, the distribution of the horizontal displacement is the superposition of horizontal displacement generated by a single tunnel construction. With the increase of the layer loss rate, the maximum settlement and settlement range are increasing when the right line passes alone. When the layer loss rate of the right tunnel remains still, the central line of settling tank gradually approaches the axis position of the left tunnel, and the position where the maximum settlement of the settling tank appears will move with the increase of the layer loss rate of the left tunnel. The field monitoring data have verified the accuracy of the simulation results, indicating that the layer loss rate of the right line of Malian shield tunnel is 2.5％, and that of the left line is 2.4％.%以广州地铁9号线4标段马莲盾构隧道施工为例,利用Plaxis 3D Tunnel有限元分析软件分析了近距离平行盾构隧道施工引起的地面沉降规律.研究结果表明:右线单线穿越时,地面沉降呈正态分布,水平位移呈"蝶形"分布;双线穿越时,地面沉降呈"W"型分布,水平位移的分布是单个隧道施工产生的水平位移的叠加;随着地层损失率的增加,右线单线穿越时的最大沉降量和沉降范围均不断增大.在右线隧道体积损失率一定时,随着左线隧道体积损失率的增大,沉降槽中线逐渐接近左线隧道的轴线位置,沉降槽最大沉降量出现位置也随之移动.现场监测数据验证了模拟结果的准确性,也说明马莲盾构隧道右线地层损失率为2.5％,左线地层损失率为2.4％.
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