Tunnel Treasure Peak Tunnel in the Existing Railway Tunnel Construction Technology

Baofeng Tunnel total length is 7377m,it is the one of the key part between Kunyang and Yuxi of the railway which is from Kunming to Hekou.The exit zone(D2K17+615) is under-passing the Kunyu Railway,its tunnel front is 50m far from the railway and 27m high from subgrade of that.It is difficult to build up a tunnel under-pass an existing railway without affecting its normal operation.For ensuring both line safety and traffic safety and achieving the success of this tunnel construction,some key points the author points out as follow.Firstly,doing reinforcement in advanced.Secondly,have a reasonable construction technique during the whole construction.Thirdly,strengthen primary support.Finally,control the settlement strictly.