Study On The Key Problems Of Variable Section Conjugating Construction Between The Existed And New Tunnels

With the development of inter city underground rail transit and urban subway networked in china, many conjugation problem in metro struction will emerge undoubted. At present, there are not many conjugation problem in metro struction in china, while conjugation problem in tunneling at shallow depth is much fewer. So the solution of these problem will provide feasible experience on the similar problem in tunneling engineering. According to the engineering of the civil air joint stage of Xizhimen subway station, this paper makes a numerical simulation and field monitoring. The main research contents are as follows.1. By the background of the civil air joint stage of Xizhimen subway station, makes a numerical simulation on variable section conjugation engeneering under complicated condition. The main contents are summarized below.(1) The analysis on stress changes of transitional structure.(2) The analysis on stress changes of the existed tennel conjugation structure.(3) The analysis on crown settlement of new tunnel and the existed tennel, and the analysis on differential settlement between new tunnel and the existed tennel.2. It makes a field monitoring, the main projects of monitoring and studying content are as follows.(1)The monitoring on stress changes of the existed tennel conjugation structure. The monitoring instrument is XJM steel chord surface strain gauge. The main studying content is stress variation law of the existed tennel conjugation structure.(2) The monitoring on stress changes of initial grid and soil pressure bwteen initial grid and the rock around. The monitoring instruments are XJG-2 steel chord reinforce stress meter and XYJ-3 steel chord Pressure cell. The main studying content is stress variation law of variable section tunnel structure.(3) The monitoring on crown settlements of transitional stage and existed tennel. The main studying contents are deformation of transitional stage and differential settlement between new tunnel and the existed tennel.3. By conjugation experiment between new waterproofer and old waterproofer, we get the best plan on waterproof conjugation. It that choosing Waterproof Rolled Sheet Made of SBS Modified Asphalt as transitional material to link ECB waterproof roll and mixed waterproofer by glass fabic and asphalt.