Filed Test And Numerical Simulation Study On The Deep Foundation Pit With Single Fulcrum Pile-Anchor Support

In recent years, with the rapid development of the economic construction, urban high-rise buildings sprang up like mushrooms in large numbers, high-altitude development of buildings and utilization of underground space becomeing the inevitable choice for sustainable development in the process of urbanization, which result in the sharp rising of foundation pit engineering. On the one hand, practice is ahead of theory in the foundation pit engineering practice, and on the other, theories can not correctly reflect the actual construction process and environmental effects. Therefore, it will strongly promote the economic development and social progress to research and improve the theory of foundation pit support, and has far-reaching practical significance.Firstly, the research progress of foundation pit support, which including design theory, calculation methods, model and field tests and numerical simulation, is reviewed and summarized. Four aspacts of deficiencies can be summed up as follows, the disjunction of theory and practice, the lack of research results of interaction and field test, the imprecision of soil displacement calculation on the basis of conventional methods and the inadequacy of research on foundation pit with additional load on top.Secondly, design calculation of pile-anchor supporting structure is carried out on the platform of F-SPW by using the existing foundation pit design and calculation methods, which provides a gauge for field tests and numerical simulation results.Thirdly, based on the laboratory building foundation pit engineering of Qinhuangdao Campus of Northeastern University, field tests are conducted from four aspacts such as soil pressure, pile internal force, bolt deformation, and axial force of anchor, and provide basis for testing the reasonableness of conventional method and the correctness of numerical simulation results.Fourthly, numerical simulation is proceeded by using FLAC3D on the basis of the foundation pit engineering, and the calculation results are analyzed and summarized which including, unbalanced force of the numerical model, vertical stress of soils, horizontal and vertical displacement of soils, supporting pile moment and variation of bolt axial force over time and its length, as well as the changes of soil horizontal displacement and axial force of bolt under different bolt prestress and different additional load on top of the pit.Finally, some beneficial conclusions are obtained based on the above-mentioned contrastive analysis, which will be providing basis for foundation pit engineering being designed and constructed safely and economically.