| The combined support structure of steel pipe and steel sheet pile(PUC)is a new type of combined support structure,which is formed by the combination of steel pipe and steel plate pile.It has the advantages of water stop of steel sheet pile and large rigidity of steel pipe.although there are several cases in China that have successfully applied the PUC combined supporting structure,the theoretical research is seriously lacking,and it causes the phenomenon that the theory is seriously lagging behind the practice because this combined supporting structure is relatively novel.Based on the research method of traditional steel sheet pile retaining structure,this paper studies and analyzes a form of combinations of steel pipe and steel sheet pile supporting structure.Firstly,a unit of steel pipe and steel sheet pile combined supporting structure is studied,and then According to the design method proposed by the author,a soft soil foundation pit in the middle and lower reaches of the Yangtze river is designed,and the foundation pit is simulated by ABAQUS finite element software to analyze the stress and deformation of the supporting structure,the deformation around the foundation pit and the soil at the bottom of the pit.The main research contents and results are as follows:(1)Briefly summarize the domestic and international research status of steel sheet piles,steel pipe piles and combined support structures,and point out the current problems of the PUC combined supporting structure: sectional characteristics of PUC combined supporting structure and its design method;(2)Based on the research of the stiffness of the steel sheet pile retaining structure,the unit stiffness of the PUC combined supporting structure is studied,the stiffness calculation formula is obtained,and it is also concluded that the load distribution relationship between steel pipe and steel sheet pile in the re-PUC composite support structure should be based on the principle of stiffness distribution.(3)Summarize the calculation method of soil and water pressure and internal force of support structure.According to the design calculation method of traditional steel sheet pile,the design calculation method suitable for the PUC combined supporting structure is proposed.(4)For a foundation pit in Maanshan,the design method of PUC combined support structure proposed in this paper is adopted,and the three-dimensional numerical simulation of excavation of foundation pit is carried out by ABAQUS toanalyze the support effect of PUC combined support structure,and the simulation results show that during the excavation of the foundation pit,the internal force and deformation of the PUC combined support structure,the settlement and horizontal displacement of the soil around the foundation pit,and the deformation of the basement all meet the requirements of the specification. |
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