北京地铁14号线高家园站-望京站区间单洞双线盾构临近穿越群桩的响应与防护

为减小盾构隧道施工对邻近群桩基础的影响,对10 m内径盾构穿越的机场快轨群桩响应进行数值模拟,分析盾构法隧道施工引起的群桩变形及内力变化情况。结果表明,开挖后桩身发生弯曲变形,桩身内力发生明显变化,前桩具有隔断作用,隧道施工对群桩中后桩的影响较小。群桩邻近盾构时采用复合锚杆桩作为隔断桩,复合锚杆桩加固桩侧土体的同时,可采用多排组合形成较大隔离刚度,套管施工可有效控制施工期间的环境影响。

Response of Existing Bridge Piles Induced by Shield Boring and Countermeasures: Case Study on Construction of Running Tunnel from Gaojiayuan Station to Wangjing Station on Line 14 of Beijing Metro

During the construction of the running tunnel from Gaojiayuan Station to Wangjing Station on Line 14 of Beijing Metro, the 10 m diameter shield passes close to the existing foundation piles of a bridge of the airport transit line. In this paper, the response of the existing bridge piles to the tunneling is simulated, the variation of the deformation and internal force of the existing piles caused by the tunneling are analyzed, so as to reduce the impact on the existing piles caused by shield tunneling. Results show that after the shield passes, the bending deformation and internal force of the existing piles have obvious changes. And the isolation mechanism of composite anchor piles is also studied. The result shows that the front piles have isolation effect, therefore the impact on the rear piles caused by the tunneling is not so serious. The following countermeasures are adopted: several rows of anchor piles are installed to achieve bigger isolation rigidity; grouting is made for the surrounding soils; casing is installed to reduce the impact on the environment.