Study And Application Of NATM In The Tunnel Of Furong Mountain

The NATM is vast applied in tunnel engineering, but it is not good insome problems of complicate conditions. The main purpose ofdissertation is to research the designing and construction technique ofNATM in the unfavorable geological condition (such as fault, coal bedand karst cave). The complicated conditions of Furong mountain tunnelmain include as follow: first, because the tunneling is in the limestoneand carbonaceous limestone and the rainfall is abundant, so there is karstcave in limestone. It is possible to have water and mud bursing. Second,there is the coal—bed in the stratum, the coal bed mixes the carbonmonoxide formed in the istory, it is possible that it have the gas spillagein tunnel construction process. Moreover it must be good at the work ofaeration and checking the gas concentration, ensure the constructionsafety. Because the engineering geological condition of coal seam is bad,it must prevent from phenomenon of the coal seam outstanding, thecollapsing of wall rock, the motion of wall rock etc; Third, tunnelingmust cross three fault; Fourth, The groundwater is abundant, the tunnelround there is the rock cranny water growth in the rock, its hole is thewaterproof shale strata. The groundwater has resoluabity erosion to theconcrete.Based on principle of New Austria Tunneling Method, divided thewall rock of tunnel into three types, found a general former system.Because grade of wall rock is very low, for the sake of the constructionsafety and improving bearing capacity of wall rock, it must do advancedsupport for the wall rock. the form advanced support mainly contain shortgrit supporting shield, advanced anchor supporting, small ductulegrouting, advanced press grouting supporting. Run before the anchor manpole to pay to protect, the small pipe notes the syrup and prepares to pressto note the syrup to pay to protect. It can achieve effect of water seal bygrouting in area which groundwater is abundance. And then have soilnailing supporting after excavating, and then have second lining. In theprocess of construction, it can have the purpose of safety and economy by observation of the wall rock, and then analyzing the observation value. Italso provides basis for offering ameliorating supporting parameter andfounding early-warning system.