Abstract：Research purposes:Most of the multi － arch tunnels are the highway symmetrical multi － arch tunnel in China for over 30 years． There is little unsymmetrical multi － arch railway tunnel in China． Therefore，it is necessary to research the unsymmetrical multi － arch railway tunnel． In this paper，taking the Xinzuofang Tunnel of the newly － built Lazhou － Chongqing Railway as the engineering background，the construction processes of the unsymmetrical multi－arch railway tunnel with two kinds of the different construction procedures was simulated under the unsymmetrically loaded condition of the Grade 5 surrounding rock in order to obtain the loading bearing situation，the deformation feature，construction method and support system for the unsymmetrical multi － arch tunnel．
Research conclusions:From the analysis of the load bearing and deformation of key parts of the tunnel structure system during the excavation，it is concluded: (1) During excavation，the stress and deformation of the key positions of the left and right caverns and on the top of the middle partition wall follow the change regulation of the construction process．(2) The three bench of the middle pilot tunnel + right pilot tunnel + left tunnel is available for construction of such kind tunnel．(3) The unbalance support system should be used for the large span unsymmetrical multi － arch tunnel．(4) In order to solve the problem of water leakage on the top of the middle partition wall，the small pilot pipe should be installed and grouting should be conducted in the V area on its top． The rock on the top of the middle partition wall should be reinforced to improve its impermeability． The calculation result provides the reliable basis for the tunnel design and the reference to the similar works．
Lv Jianyun． Construction Technology for Shallow Doule － arch Tunnel with Bias Weak Rock ［J］．Journal of Railway Engineering Society ，2011(3) : 72－75．
［2］ 王晓放，李存德，宋玉香． 双跨连拱隧道侧导洞扩挖动力分析［J］． 石家庄铁道学院学报，2002 (S) :5－7．
Wang Xiaofang ，Li Cunde，Song Yuxiang． Analysis of the Blasting Vibration Effect for Enlargement of Double － arch Tunnel ［J］． Journal of Shijiazhuang Railway Institute，2002(S) : 5－7．
Wang Jun， Xia Caichu， Zhu Hehua， etc． Site Monitoring and Analysis of Non － Symmetrical Multi － Arch Highway Tunnel［J］． Chinese Journal of Rock Mechanics and Engineering，2004(2) : 267－271．
Deng Jian，Zhu Hehua，Ding Wenqi． Finite Element Simulation of Whole Excavation Operation of a Unequal － span Double － arch Tunnel ［J］． Rock and Soil Mechanics，2004(3) : 477－480．
Wang Wei，Huang Juan，Peng Limin，etc． Analysis on the Structure Stability of the Unsymmetrically Loaded and Connecting － arch Tunnel Caused by Different Construction Orders ［J］． West － china Exploration Engineering，2004(10) : 105－108．
［7］ 何川． 公路双联拱隧道［M］． 北京: 人民交通出版社， 2006．
He Chuan． Highway Arch Tunnel［M］． Beijing: China Communications Press，2006．
Shen Yusheng，Zhao Yuguang． Site Monitoring and Analysis Reseach on Surrounding Rock Deformation of a Biased Double － arch Tunnel［J］． Highway，2005 (4) :194－198．
2012, Vol. 29 
版权所有 © 2014 《铁道工程学报》编辑部