Numerical Analysis Of Top-Down Construction Technique And Study On Monitoring For Deep Excavation Engineering In Soft-Soil Areas

As the improvement of cities' civilization and the development of construction technique, building construction meets problems of restrict control on site area and circumstance protection. In result, the so-called Top-Down Construction Method (TDCM) get more and more appliacation which promotes its progress. TDCM has resolved commendably a series of problems in the field of underground engineering, for example, the period of deep excavation is long, the impact of the project construction process on the surrounding circumstance is serious, the charge of shoring is expensively, etc. And TDCM has been an efficency method in deep excavation engineering of highness storied building in city, especially in reconstructing and rebuilding of old city. In the region of soft clay, there are quite lot problems and questions in TDCM need to be solved, which relates to the appropriate control of differential settlement of structure in vertical direction, and the release of the impact of the project construction process on the surrounding circumstances. Furthermore, provide reliable analysis method for project, in order to direct the whole process of TDCM, establish the scheme and sequence of construction, reduce construction cost of TDCM, expedite the construction pace, control the problem in the process of TDCM.In this paper, seventy project examples were collected in China and overseas area which were applied TDCM, and special features were summarized, in order that the present situation and tendency of TDCM application can be overall known. Further more, the two-dimensional analytical theories of TDCM in Shanghai soft clay area is researched completely, also puts forward a series of computing methods of FEM for TDCM, consolidation is calculated at the same time in whcih, then resolves some critical and difficult question of TDCM in Shanghai soft clay area. The main research contents are as follows:(l)Modified Cam-Clay model theory is expatiated for soft clay in Shanghai, and the parameters of Cam-Clay model are studied by triaxial shear test and site compress test. Surrounding wall, supporting beam, pillar and project pile are simulating by...