道岔区框架桥桥式盾构顶进施工技术

The Jacking Construction Techniques of a Frame-Bridge-Type Shield in the Switch Section

在繁忙运营线下采用桥式盾构法顶进大跨度框架桥,具有行车干扰小的优势;但该工法对地质条件、覆土厚度、顶进后背、盾构制作质量、反拉系统等的要求高,一直较难得到推广。详细介绍九江市琴湖大道下穿铜九、九炼专用线工程采用桥式盾构顶进框架穿越两组道岔的施工,综合利用下滑道、横向钢筋混凝土挡土梁、反拉系统的共同作用,有效地解决了在地质条件不良、穿越道岔群、大跨度框架等不利条件下,盾构顶进施工安全。并提出桥式盾构顶进法今后应向盾构结构模式化、反拉数据准确化、子盾构掘进系统机械化的方向发展。

Using a bridge-type shield to jack a large-span frame bridge under a busily-operating railway has the advantage of causing less effect on the normal operation of the railway above.However,the construction technique demands much in geological conditions,soil thickness,the roof into the shield back,the high quality of the shield,the counter-loop system,etc.,owing to which it is often difficult to popularize the technique.Even so,the project of the Qinhu Avenue in Jiujiang City,which undercrosses the Tong-Jiu and the Jiu-Lian Special Railways,uses a bridge-type shield successfully to jack a frame through two groups of switches,in which case comprehensive use is made of the lower slide,the transverse reinforced concrete retaining beams and the counter-loop systems.With all the above-mentioned techniques adopted for the project,the problem of the construction safety in shield-jacking under the adverse conditions of poor geology,crossing groups of switches and large-span frames is effectively solved.Upon the basis of the smooth completion of the project,it is advised that the techniques should progress towards the standardization of the shield structure,the accuracy of the counter-loop data and the mechanization of the tunneling by the sub-shield systems in the future.