大型盾构隧道穿越铁路框架桥的影响分析

Analysis of the Influence of a Large Shield Tunnel Passing Under a Railway Frame Bridge

杭州环城北路隧道为双向4车道大型盾构隧道,施工中要下穿沪杭铁路三孔连续框架桥。文章对隧道施工中框架桥结构及铁路运行的安全性进行了评价,并提出了相应的安全控制措施。首先应用Peck公式预测了不同地层损失率下的铁路框架桥的沉降;其次采用ANSYS大型有限元软件,对铁路框架桥下土体不加固与加固两种工况下,盾构下穿掘进中造成的铁路框架桥的沉降及应力变化进行了分析。结果表明,铁路框架桥下土体加固后,可有效地减少盾构掘进造成的地层损失(在1%以内),框架桥的沉降及由此引起的附加应力满足安全要求,盾构施工对铁路框架桥运营的影响在安全范围内。

A large diameter shield tunnel （bi-directional and four-lane） on the north ring road of Hangzhou is to be constructed and will pass under a three-hole continuous frame bridge. The safety of the railway frame bridge and railway operation during tunnel construction is evaluated, and some control measures are put forward. The settlement of the railway frame bridge under different ground loss ratios is predicted by the Peck formula, and the settlement and stress variations of the railway frame bridge during shield tunneling is analyzed by ANSYS finite element considering the two cases of a reinforced and non-reinforced soil mass. The results show that drivinginduced ground loss can be effectively reduced （within 1%） and that the values of settlement and additional stress meet the safety requirements if the soil mass is reinforced.