军都山隧道黄土试验段垂直位移观测及分析

本文应用WRM-3型多点位移计在军都山大跨度浅埋黄土隧道施工中进行拱顶垂直位移监测并成功地预报了隧道大塌方。重点分析了2号孔位移全过程的实测结果。位移与施工,地中相对位移与地面下沉等的关系也进行了初步分析和讨论。认为在此种工程条件下垂直位移监测是确保隧道稳定安全施工的重要一环。得出了上部(约1/3洞高)开挖最大垂直位移量是在隧道开挖超过观测孔1.2倍洞径内发生,并且下部落底开挖垂直位移变化不大,仅相当于上部开挖最大位移量的30-40％的结论。

Measurement and Analysis of Vertical Displacements of Loess Test Section in Jundu Shan Tunnel

The Vertical displacements on the crown during excavation is monitored with WRM-3 type extensometer. Successful prediction of extensive coupes in a shallow buried loess tunnel with a large span is made. The emphasis of this paper is put on the interpretation of the whole measuring process at borehole 2. The relations between displacement and excavation of the tunnel, relative displacements in the ground and the surface subsidence are discussed tentatively. The results indicate that monitoring vertical displacements under this engineering condition is very important to ensure the stability and safe excavation of the tunnel. Finally, some conclusions are drawn that the largest vertical displacement during the excavation of top part (about 1/3 height ) of the tunnel occurred when the working surface was in the distance of 1.2 tunnel diameters from the measuring hole and that the change of vertical displacements was small during the excavation of the low part, which was equal to 30-40% of the largest one.