Study On Settlement Mechanism And Control Technology Of Shield Under-passing Frame Bridge From High-speed Railway

The increasingly dense high-speed railway network will have a profound impact on Chinese and rewrite the economic territory, but also makes the construction of subway underpass the existing high-speed rail line difficult. It is necessary to ensure the safety of subway construction and prevent the high-speed rail have excessive settlement,which is very mportant to ensure the normal operation of high-speed railway. Due to the importance of high-speed railway, [2012]23 document published by the railway ministry clearly stipulates that when the high speed railway and highway crossing, priority should be given to the high-speed rail span highway plan. However, in most cases, the subway is laid along the urban main road, which has resulted in more and more underground rail bridges.In this paper, taking Chengdu Metro Line 4 through ChengmMianLe high speed railway frame bridge as engineering background,The simulation of shield tunneling is carried out by using FLAC3D finite difference software, analyzed the settlement law of subway underpass the High-speed rail frame bridge and the settlement influence of different excavation sequence, different buried depth and different line spacing. The application of grouting lifting method in this project is introduced in detail and The main contents are as follows:(1) According to the related railway code and the zero settlement after construction, the control standard of maximum settlement of high-speed rail is no more than 3mm.(2) Based on the established Ballastless Track - high-speed frame bridge - the overall calculation model of foundation excavation,the research of shield excavation to distance high-speed rail frame bridge at different locations, settlement of high-speed rail and bridge frame bridge, analyzed and summarized at the edge of the frame bridge settlement process with the subway excavation process of law. The influence of ground pre grouting reinforcement on control settlement is analyzed and compared.(3) The influences of single and double track excavation, different buried depth and different line spacing on the settlement of high-speed rail track and frame bridge are compared and analyzed.(4) Grouting uplift technology is one of effective measures to achieve zero settlement after construction, this paper introduces the construction method of grouting uplift process,selection of grouting material,grouting and curtain grouting hole layout, grouting pressure calculation etc.