Study On The Status Evaluation And Control Standards Of The Existed Bridge Adjacent To Subway Constrution Site

Main Beijing subway lines cross the centeral district of city, where many viaducts and elevated pedestrian crossings have been built. Subway will inevitably cross at the sides of or under the foundations of municipal bridges. So soil displacement caused by subway construction will probably cause the settlement and additional stress of nearby bridge foundations. If the settlement and additional stress of nearby bridge foundations are greater than definite values, the bridges will be damaged, affecting the normal use or the safety of these bridges. To ensure the normal use of these nearby bridges, the status investigation and evaluation, the establishment of settlement control standard of these nearby bridges should be carried out in the construction. At the same time, the construction influence forecast with construction stages, special construction and protection methods should be adopted for the safe and economical construction. Now the basic procedure, contents and standards on subway construction nearby bridges are not sophisticated. To protect the surrounding enviroment and decrease the safety risk of surrounding enviroment, it is urgent to study the key technical problems of the influnce and control of subway construction nearby bridges.The status investigation and evaluation, the analysis and forecast of construction influence, the establishment of settlement control standards of nearby Guomao Overpass are mainly studied in this thesis combined with Guomao Station Project of Subway Line 10. The strength of concrete, thickness of steel covering layer of uperstructure, pier column, and coping are detected. The modality test analysis, settlement calculation and bearing capacity evaluation of pile foundation are separately finished according to the different structural styles of beams. Then the remained permission differential settlements between adjacent bridge piers are presented along and across the bridge. 3D nonlinear numerical model including northwest duct of Guomao Station and nearby bridge piles are founded, construction processes of tunnel-pile mining excavation are modeled, and the influence of typical construction stages to soil and bridge foundation are forecasted. Based on the status evaluation and forecast of construction influence, the control standards of differential and absolute settlements are established...