利民堡深埋红粘土隧洞的新奥法施工

粘土地层特别是在地下水位以下进行隧洞开挖时，随着洞周应力的释放将产生较大的收敛变形，极易导致围岩失稳并造成塌方，对于在埋深较大的塑性粘土地层中开挖隧洞，其施工难度就更大。作为一个典型工程实例，引黄南干５＾＃洞利民堡洞段粘土覆盖层厚度深达１８０ｍ，围岩应力高达３．６ＭＰａ，但由于合理运用了新奥法施工，包括采用分步开挖断面、适当预留收敛变形量、缩短开挖循环进尺、加密格栅拱架和及时喷混凝土支护等综合措施，因而顺利贯通。

New Austro Tunnel Method construction in deep buried red clay tunnel section in Liminbu of the Wanjiazhai Yellow River Diversion Project

When excavate within clay stratum,particularly construction should have to take place under ground water level,it is easy to lead to unstable of surrounding rock and cause collapse with the release of surrounding stress,a higher convergence deformation will happen.If construction have to take place in deep buried plastic clay stratum,the difficulty of construction will be much higher.As typical example,the cover deepness of clay of tunnel 5 of Liminbu tunnel section of south main of the Yellow River Diversion Project reach to 180 meters and stress of surrounding rock reach to 3 5 MPa higher.But for the successful use of new method construction,which includes excavate in step,appropriate pre expect convergence deformation amount,short the advance progress,and use stiffened arched girder,as well as shotcret for support in time and so on.It is smoothly got through now.