大粒径卵石地层中盾构下穿既有铁路的影响分析

Analysis of the influence of shield tunneling construction under existing railways in large-size pebble stratum

为了研究在大粒径卵石地层中盾构下穿既有运营铁路引起的地层及轨面变形规律,以及对比不同隧道加固措施的效果,文章以洛阳市轨道交通2号线刘富村出入线区间盾构下穿焦柳铁路为工程背景,通过有限元软件进行了4种不同工况的模拟,包括无隧道保护措施的工况、采取路基提前注浆加固的工况、采取隧道洞内深孔注浆加固的工况以及同时采用路基注浆和洞内深孔注浆的工况。实际工程采用路基注浆和洞内深孔注浆2种加固措施,实际监测数据与模拟结果具有良好的一致性。结果表明:在大粒径卵石地层中盾构下穿施工会对既有铁路产生较大影响,最大沉降值发生在左线隧道正上方,右线隧道的开挖会对左线隧道产生较大扰动,是左线隧道工后沉降产生的主要原因。在同时采用2种加固措施后,地层和轨面沉降值均符合沉降控制标准要求。可见,同时采用2种加固措施后,可显著减少盾构下穿施工对既有铁路的影响,是保证盾构施工和铁路运营安全的有效加固措施。

In order to study the deformation law of the ground and rail surface caused by the shield tunneling under the existing operating railway in the large-size pebble stratum,and to compare the effect of different tunnel reinforcement measures,four different working conditions are simulated by the finite element software based on the engineering background of the shield tunneling under the Jiaozuo-Liuzhou railway in Liufu village access section of Luoyang rail transit line 2,including the working conditions without tunnel protection measures,the working conditions of subgrade grouting in advance,deep hole grouting in tunnel and subgrade grouting and deep hole grouting in tunnel at the same time.Two reinforcement measures,subgrade grouting and deep hole grouting,are adopted in the actual project,and the actual monitoring data are in good agreement with the simulation results.The results show that the shield tunneling will have a great impact on the existing railway in the large-size pebble stratum,the maximum settlement value occurs directly above the left line tunnel,and the excavation of the right line tunnel will cause a great disturbance to the left line tunnel,which is the main reason for the settlement after the construction of the left line tunnel.After two kinds of reinforcement measures are adopted at the same time,the settlement values of the stratum and the rail surface meet the requirements of the settlement control standard.It can be seen that two kinds of reinforcement measures can significantly reduce the impact of shield tunneling on the existing railway,which is an effective reinforcement measure to ensure the safety of shield construction and railway operation.