北京地铁十号线光华路站开挖群洞效应的数值模拟研究

Numerical simulation study on the multi-tunnel effect during excavation of the subway in Guanghua Road Station of Beijing metro line 10

结合北京地铁十号线一期光华路地铁站的工程和地质条件,运用FLAC3D软件对车站主体浅埋暗挖的五种不同施工顺序的方案进行模拟研究.在相同的地表荷载、固定约束和土体参数的情况下,模拟研究得出车站周围土体应力、塑性区和位移的基本变化规律,并确定群洞效应下开挖顺序的推荐方案.研究结果表明:(1)车站开挖过程中和完成后,破坏区主要集中在中洞与两侧洞之间的区域,即群洞之间部位,并从中洞两侧垂线以45°角向外扩散;(2)中洞的跨度对地表的沉降量有着明显的影响,对于群洞而言,先对左右洞室进行开挖可有效地减小开挖中洞的位移变化量;(3)中洞的拱形支撑能有效抑制地表的破坏区,考虑群洞效应时应先保证中洞洞顶部分的强度.

In this paper,based on Guanghua Road Station geometric materials,the numerical simulation of the station under five different excavation orders was carried out by FLAC3D software.Through the comparisons of different excavation orders with the same support parameters and the same loading condition,the regularities of soil-stress,plastic region and displacement transformation about the station were put forward.After analyzing,the recommending excavating order of the multi-tunneling construction was proposed.The results showed:(1) the plastic regions mainly exist in the areas between different holes,and along the line which presents 45° from the vertical direction of the middle hole;(2) the horizontal expansion of the section of the middle hole plays an important role in the downward displacement of the ground surface,but to the multi-tunnel construction,excavating the left and right hole firstly can reduce the displacement effectively;(3) the arch structure of the main hole plays an very important role in reducing the downward displacement of the ground surface.