Deep Foundation Pit Support System For A Bank's Comprehensive Business Building

In recent years, the gradually accelerating process of urbanization result in the absence of land resources and which make land resources become more and more precious. The land space is compressed and the buildings become higher and higher. Gradually, the exploitation of underground space become another optimization of designers. Based on deep foundation pit engineering of a multi-function building, the writer simulate the excavation process with ABAQUS6.10. Meanwhile, the writer study the bending moment and deformation of H section steel by changing the parameters about the location form of H section steel,the pressure applied on the surface near the side of the slope(0k Pa?20k Pa?40k Pa?60k Pa),the position of inner support in vertical direction(3.4m?5.4m?7.4m)and so on. At last, in order to explore the stress and deformation mechanism of SMW pile, the writer make a comparison between the calculated results and the measured values, from which the writer not only verified the feasibility and rationality of simulation by using ABAQUS but also obtain the following conclusions:(1)The stress of SMW is metabolic during the process of excavation. The curve of the distribution of bending moment along the depth direction presents “S”, the max value of the bending moment of H section steel is increase along with the deeper of the excavation and the place where bending moment is the biggest move down accompany excavation and it appears near by the excavation surface above.(2)Under the first excavation step, H section steel in a cantilever state without any support and the place where displacement is the biggest located in the cap. After the fixing of the support, it began to play its role during the subsequent excavation. The max value of the displacement of H section steel is increase along with the deeper of the excavation and the place where displacement is the biggest move down accompany excavation and it appears near by the excavation surface above.(3) In terms of stress and deformation, with the increase of additional load near the slope edge at the top of the foundation pit, the bending moment and horizontal displacement of H section steel also increased and the growth rate increased with the increase of the additional load. In addition, the fourth step excavation(The fifth working condition) under each additional load, the curve of the distribution of bending moment and displacement along the depth direction is similar respectively and presents “S” and “Spoon” shape.(4)As for different layout of H section steel, the curve of the distribution of bending moment and displacement along the depth direction is similar respectively and presents “S” and “Spoon” shape. For these three kinds of layout form about H section steel, from sparse to close, the average spacing of H section steels is narrower and the load subjected to the unit area of H section steel decreased, which leaded to the diminution of the horizontal displacement of corresponding sections.(5)The maximum bending moment which act on the H section steel increased at first and then decreased along with the moving down of the layout of support. In addition, the place where the maximum bending moment appeared transfer from the inside above to the outside below of the bottom the foundation pit. The horizontal displacement of H section steel excessively increased along with the moving down of the layout of support, and the lower the support move to, the bigger the increased amplitude of the displacement appeared.(6)During the process of designing, engineering designers shall take the space effect of supporting system of soil into consideration in advance and which should be made full use of to suppress the stress and deformation of the supporting system subtly. Modulate the vertical position of inner support, change the layout form of H section steel by calculation, from which, the stress and deformation of the supporting system that generate during the process of excavation may be controlled in a certain range, on the premise of ensuring security, we are able to reduce the project cost, save the economic costs.