铁路客运专线明挖大断面隧道施工监测分析

Construction Monitoring Analysis for Large Cross-section Tunnel Excavation of Passenger Dedicated Railway

通过对海南东环铁路美兰机场明挖隧道试验段施工跟踪监测,获得了围护结构变形与内力变化的一些规律.监测表明:1)围护结构水平位移随工期的延续而增加,基坑开挖完成后逐渐趋于稳定,最大位移值大约出现在开挖深度的三分之一处;2)锚索拉力随基坑施工工况不同而变化,基坑开挖中漏水、涌砂等情况对锚索拉力也有较大影响;3)钢支撑轴力控制标准较为严格,承载能力还有一定潜力,轴力变化平稳,略有波动.

A field monitoring programme was carried out for the cut and cover railway tunnel near Meilan Airfield in Hainan province,and varied laws on deflections and internal forces of excavation retaining and protecting were obtained. There are several monitoring on clusions as follows： 1） The horizontal displacements of retaining structure increases with the construction duration and tends to be stable gradually after the foundation pit excavation is completed. The largest displacement appears on about one third depth of the excavation. 2） The axial force of cables changes greatly during the excacation of the foundation pit,and sand and water effuse quickly between high-pressure rotating piles,which has great influence on the axial force of cables. 3） The steel supports adoptes strict control standards and has some potential bearing capacity. The axial force of steel support changes steadily and fluctuates very little.