Research Of Foundation Stability In Subway Station By Combination Of Open-cut And Cover-dig Method

This article relies on the Beijing subway 9th line of Fengtai North Road station excavation, The existing methods of construction, we put forward a new method-The combination of open-cut and cover-dig method. In response to this method, foundation support system for the study of parameter influence and optimization. The main conclusions are as follows(1)By analysing the characteristics of the various construction methods, compare and get their shortages:For open-cut method, its construction speed is slow, human capital investment is large, and has a significant impact on the environment. For cover-dig method, its cost is high, The complexity of upper loads on structure and support system leads that the land subsidence and the structural deformation are beyond control. Mining method is easy constrained by the geological conditions, and its construction speed is also slow. For these shortages, we put forward a new method-The combination of open-cut and cover-dig method. This method cost low, construction speed is fast, mechanization degree is better, and it can effectively meet the needs of the surrounding environment and traffic.(2)The combination of open-cut method,mining method of support system parameters, we can obtained impact of the law:horizontal displacement of pile body endure number of support,location of finishing support,Installation time,influence of pre-tension; displacement of pile top location of first support,impact of the size of pre-stressed; number of inner support of pile; ground surface settlement is mainly affected by the number of support. The Fengtai North Road Station Foundation's support system parameters laws on the use of optimized these laws, and compared the results of old project and new project programs to arrive at the feasibility of the optimization.(3)This paper described how to use the combination of open-cut and cover-dig method to build the metro station and analysed the influence of the foundaton caused by excavation with finite element calculation method.Compared the calculated value with the measured data,it proved the correctness of the calculation and the simulated calculation gave the practical engineering more guiding value.