Research On Evaluation Of Stability Of Retaining Structure By Bored Occlusive Piles In Deep Foundation Pit

With the accelerated process of urbanization in China, numerous engineering of deep foundation excavations arised as a result of a large number of high-rise buildings and metro. Meanwhile, disasters caused by the excavation of deep foundation occurred frequently. Therefore, stability evaluation and early warning of deep foundation construction are very importantThis thesis focuses on indexs which affect safety of deep excavation construction. Combing with Binhe station of Hangzhou Metro Line 1, theoretical calculations, numerical simulation and monitoring measurement are used to analys foundation changes. As a result, whether the foundation is in a statialized state can be judged, and then construction of foundation will be guided successfully. In this thesis, the following research works are carried out:(1) Deformation mechanism of deep foundation pit is analyzed first, and then influencing factors about deformation of deep foundation are summarized. The main factors are design, construction and geological conditions.(2) Entropy method and extenics theory are introduced. Combing with evaluation of extenics, index weights determined byentropy method are summarized. horizontal displacement of pile jacking, surface subsidence, basement high, bending moment of pile shaft and strut axial forces which obtained in actual construction are used as analytic indicators to evaluate the stability of the structure.(3) FLAC3D is used to simulate the Binhe station of Hangzhou Metro Line 1, change law of indicators of supporting technology for deep foundation pit are obtained at various stages of construction。(4) Extenics and numerical simulation are compared; moreover, conclusions are more consistent. Use of extenics method to evaluate whether the foundation ditch is in a statialized state is feasible, and their results have been proved.