双线地铁盾构施工引起的地表沉降分析及施工控制

为了研究双线隧道盾构施工对周围土体的扰动规律及其控制措施,在讨论双孔平行隧道地表沉降计算公式在厦门地铁某区间隧道适用性的基础上,采用双孔平行隧道地表沉降计算公式、数值模拟及现场监测3种方法,揭示双线地铁隧道盾构施工引起的地表沉降分布规律和地表动态变形特性,分析影响地表沉降的施工控制参数的效果。结果表明:(1)双孔平行隧道地表沉降计算公式具有较好的适用性,双线隧道盾构施工完成后,地表形成非对称的"W"形沉降槽;(2)地表沉降本质上是盾构施工引起的土体损失累积造成的,在开挖面到达目标面时,实测地表沉降达到最终沉降值的45%;(3)设置合理的同步注浆、土舱压力和推进速度参数,可以有效控制地表沉降,建议增加同步注浆量作为控制地表沉降的首选措施。

Analysis of Ground Settlement Induced by Twin-tube Subway Tunnel Excavation and it's Construction Control

In order to study the disturbance law of the surrounding soil induced by shield construction of twin-tube metro tunnels and it's control measures, the applicability of the ground settlement calculation formula of twin-tube metro tunnels for a certain section of Xiamen subway was discussed. Then, the distribution law of ground settlement induced by shield construction and the features of surface dynamic deformation during the tunnel excavation were presented by using ground settlement calculation formula of twin-tube metro tunnels, numerical simulation and in-situ monitoring. And the effectiveness of construction control parameters that affecting surface settlement was analyzed. The results showed that:(1)The ground settlement calculation formula of twin-tube metro tunnels had a good applicability, and unsymmetrical "W"-shaped settlement trough was formed after the twin-tube subway tunnel shield construction completed;(2)The ground settlement is essentially caused by the accumulation of soil loss, and the observation ground settlement accounts for 45% of the final settlement when the shield excavation face passing the target section;(3)The ground settlement can be controlled effectively by setting reasonable synchronous grouting quantity, soil tank pressure and propulsion speed, it is suggested that increasing the synchronous grouting quantity should be the first choice to control the surface settlement.