Study On Key Construction Technology Of Guiyang Metro Under Complicated Geological Conditions

YCK36+300-Youzha-Street station interval,Youzha-Street station belongs to the 2nd Line project of the Guiyang City Metro.There is the complex geological conditions and construction risk in the construction project because of the following:(1)The Guiyang subway is a typical karst stratigraphic horizon,geological conditions are very complex,there is mud and water bursting risk of the construction when the subway through the karst formation;(2)Guiyang subway crossing the Nanming River and Tuanpo bridge,where exists the Nanming River thrust faults full of the crushed rock and developed karst.the minimum depth of the subway is about 5m when crossing the Nanming river and there are significant risks in construction;(3)The subway station belongs to the large span shallow tunnel,and the minimum depth is about 10 m and overburden layer is about 8m where the bad geology is the red clay and karst.The initial Arch cover excavation construction is used for the station,and the roof risk fall exists in the construction of the station.In this paper the studies on the difficulties in the construction is carried out,and the specific content is as follows:(1)The supporting forms of interval metro tunnel in the different position are studied.And the corresponding supporting schemes and the corresponding supporting design parameters are given.(2)In view of excavation of the subway station,14 parts is divided into in the construction.And the support scheme and construction scheme of the station are mainly studied in this paper.(3)According to the characteristics of the rock section of Guiyang,the blasting construction schemes of Guiyang subway are studied,and the blasting parameters are determined.Through comparison of the non-blasting constructions,the roadheader construction is selected.And the roadheader is converted more suitablely for the cold excavation in Guiyang subway,forthermore the roadheader construction parameters and construction technology are given.(4)According to the Karst topography of Guiyang metro,this paper puts forward the construction method of the Karst cave which is exposed near the arch,side and bottom of the tunnel,and the specific construction parameters are given.(5)For subway tunnel crossing the Nanming River and the reverse faults,the comprehensive construction schemes are used,such as the geological prediction,riverbed temporary paving,advance support,full section curtain grouting,and the corresponding construction parameters are also given.The above research on the construction of the Guiyang subway system under complex geological conditions,can provide support for the metro construction,and accumulate the experience of the subway construction under the karst conditions,but also provide a reference for similar construction.