淤泥填海地层近距离交叠隧道施工影响及控制分析

摘要

针对淤泥填海地层中的近距离交叠隧道工程,利用三维有限元软件PLAXIS数值模拟,计算了新建盾构隧道施工对周边环境的影响.施工将引起的临近既有线上浮14 mm,造成地表沉降变形69 mm,无法满足盾构施工变形控制要求.为有效控制盾构施工对周边环境的影响,必须对淤泥填海地层进行加固.采用二维有限元法分析了不同加固范围对隧道附加变形的影响,提出了淤泥填海地层的针对性加固方案:隧道两侧3m范围内的淤泥填海地层采用高压旋喷桩全深度加固.经计算,加固条件下既有线上浮变形和地表沉降较未加固条件分别能减小44 %和86 %.由此可知,在淤泥填海地层中,提出的加固方案能有效控制施工引起的环境变形,减小施工影响.%Aiming at the short distance overlapped tunnel in silt reclamation stratum, this paper explored the ef-fects of the construction of the new shield tunnel on the surrounding environment by the 3D finite element soft-ware PLAXIS. The construction generated 14mm moving up for the existing tunnel, resulting in 69mm of surface settlement, which can not meet the deformation control of shield construction. In order to effectively control the impact of shield construction on the surrounding environment, the silt reclamation stratum must be reinforced. Then, the effects of different reinforcement range on the additional deformation of the tunnel were analyzed by 2D finite element method. A specific reinforcement scheme for the silt reclamation stratum was proposed. The silt reclamation stratum within 3m on both sides of the tunnel was reinforced with high-pressure rotary jet grout-ing pile in full depth.It was found that under the condition of reinforcement,the existing tunnel move-up defor-mation and surface settlement can be reduced by 44% and 86% compared with those without reinforcement. The research results show that in the silt reclamation stratum, the reinforcement scheme proposed can effectively control the environmental deformation caused by the tunnel construction and reduce the construction impact.