Study On The Construction Technology Of Water Diversion Buried Culvert Under Complex

The buried culvert under the west fourth ring road is one of the most important subprojects of the South-North Water Transfer Project, and it is designed to be constructed with the shallow tunnel construction method. In such huge watermain diversion works, the long pressurized pipe with the length of more than ten miles is planned to be constructed under the city expressway, it is not still applied yet in China at present. The paper mainly focused on the study of the construction technology of pressurized pipe in complicated circumstance. Based on the theoretical analysis of design proposal and the validation of construction process, the design proposal is adjusted according to the problems appeared during construction process and the analysis of monitoring results, and the purpose of this study is to propose a proper design method of the buried culvert subproject.The finite element method is adopted in the study, and 20 sets of 3-D numerical models are conducted to simulate the construction scheme of buried culvert under the west fourth ring road in the South-North Water Transfer Project. In this thesis, the construction technology of the crossing two-lane buried culvert with long distance and small interval zone between the foundations of viaduct is mainly studied, in order to simulate the real situation during construction, so as to provide the necessary reference for the determination of key link of design, key step during construction, important point and index in monitoring survey.In this thesis, the crossing buried culvert project is classified by the foundation form of viaduct. The main classes are excavated pile form and the caisson foundation form. In the early stage of design, 2-D and 3-D FEM simulations of these two different crossing styles are conducted respectively. The minimum distance between the two-lane buried culverts is 1m, while the minimum distance between buried culvert and the foundation of viaduct is 1.85m. For each crossing style, according to the real situation, the comparison among simulations of different construction cases are conducted, and the influence on the structures such as viaduct are obtained. Finally, the construction process risk assessments of the crossing buried culvert project are carried out, and the construction schemes of the crossing buried culvert project are proposed according to the results of FEM simulations. The results show that the construction schemes can satisfy the operating requirements of viaducts, and the schemes have proved to be effective and safe. Under the condition of no standard to be followed in China, the construction of crossing two-lane buried culvert with long distance and small interval zone between the foundations of viaduct was conducted, and the engineering roadblock such as the difficulties of cavitation construction. With the application of the results of this study, the safety of subway stations, Wukesong Viaduct and the buried culvert are ensured, and the speed limit of subway have been relieved up to six month in advance. The crossing project of buried culvert under the west fourth ring road have been finished, and the maximum value of unequal settlement is only 2mm, which is smaller than the allowable deformationguideposts of structures, and the rationality of the results of study is proved.