The Comprehensive Technique To Protect The Existing Bridge At The Project Of Guomao Subway Station

Subway system is typically system engineering composed of many high technologies. During the process of metropolitan evolution of various countries, subway becomes the definite choice for large cities to make high operation efficiency and good quality of transportation. The building of subway system embodies both the level of civil planning and construction, and is also regarded as the important benchmark of the national industry development level.In China, the construction methodology which underwent from nothing to existence has made incessant progress and promotion with incorporating the local situations, in which several construction techniques as cut and cover method, undermining method,cover and cut method,shield method,sbumerged method have been adopted. Some of them even reach the advanced high level in the world. These construction techniques not only boost the development of subway system in China, but also applied to other realms of civil engineering. Since China's development of municipal planning is only on its incipient stage and the programming of lines is even more lagged, it often exists the situation in the subway construction that the new building subway struction must travel through the dense piles of bridge foundation and municipal pipelines,or beneath the city buildings.In the engineering of the Guomao station which underground structure is one of the most difficult parts in the Beijing subway project of Line No. 10, the mentioned challenges from the typical form of"multi- tunnel and cluster-pile"has to be faced to. Along with all the environmental risks the most critical, sensitive and irreversible consideration is how to ensure the safety of the bridge foundation.Basing on large quantity of engineering analysis and selection, the underground structure of the Guomao station are constructed by the Tunnel-Pile Means (TPM) with respect to the self-characteristic and engineering constraints. During the process of selection, the force analysis and displacement computation have been done for the main operation conditions in TPM. The results indicate that the TPM is the most suitable construction method for the operation in bridge regions. A large amount of argumentations and the validation from construction site also demonstrate the advantage of TPM as the major methodology over other solutions.Through the research on the effectiveness of TPM applying on the construction of underground structure of the Guomao station, the systematic technique on bridge foundation protection is proposed and also put into application. The application of this comprehensive technique realizes the construction of underground structure of subway in case of areas with critical programming condition, such as the area of Guomao Bridge in the eastern third ring, Beijing, and ensures the safety of the municipal bridge structure. The proposed technique shows the advancement, integrity, applicability and creativeness in designing subways in dense bridge foundation area.The proposed technique applied in Guomao station engineering can be of important guidance and reference for similar engineering, and is worthy of putting into further application in the following subway system engineering. While making the safe situation in the subway construction, the technique ensures enough security of the bridges in the ambient area, which lower the cost for bridge protection and maintenance.