大直径盾构并行施工对邻近高铁桩板结构路基的影响程度兮区研究

Impact Degree Zoning of Large Shield Parallel Construction on Pile-plate Structure Roadbed of Adjacent High-speed Railway

[目的]大直径盾构在长距离、小净距并行邻近高铁施工时,对既有结构及周边环境的变形要求极为严格,需要根据影响程度分区,对可能受到较大影响的区域进行防护加固。[方法]依托上海市轨道交通市域线机场联络线盾构并行沪杭高铁路基段工程,通过FLAC3D有限差分软件建立模型,分析盾构并行施工对高铁桩板结构路基的变形影响,明确不同施工条件下隧道与既有高铁的安全距离,得到盾构并行施工的影响程度分区。[结果及结论]增大隧道埋深、高铁桩板结构桩长和隧道与路基的水平距离均能减小盾构并行施工引起的路基水平位移;增大隧道埋深会增加路基竖向位移,但受地质因素影响,出现增大隧道埋深,路基沉降减小的情况;得到不同施工条件下满足变形控制指标的安全距离及盾构并行既有高铁桩板结构路基的影响程度分区。

[Objective]When a large-diameter shield is used for parallel tunnel construction adjacent to high-speed railway with long and small clear distances,it has extremely strict requirements for the deformation of the existing structure and the surrounding environment.There is the need to zone the affected area according to the influence degree,protect and reinforce the area that may be greatly affected.[Method]Based on the shield construction project of Shanghai Airport Link running in parallel with the roadbed section of Shanghai-Hangzhou Highspeed Railway,a model is established by FLAC3D finite difference software to analyze the effect of parallel shield construction on the deformation of the pile-plate structure roadbed of the high-speed railway,determine the safe distances between the tunnel and the existing high-speed railway under different construction conditions,and zone the area based on the influence degree of parallel shield construction.[Result&Conclusion]Increasing the buried depth of the tunnel,the pile length of the high-speed railway pile-plate structure and the horizontal distance between the tunnel and the roadbed can reduce the horizontal displacement of the roadbed caused by the parallel construction.Increasing the tunnel buried depth will increase the vertical displacement of the roadbed,but the roadbed settlement may reduce as the buried depth of the tunnel increases under the influence of geological factors.The safety distance meeting the deformation control index under different construction conditions and the zoning of different influence degrees when shield tunnel runs in parallel with the existing high-speed railway pile-plate structure roadbed are obtained.