| Steel sheet pile cofferdam has been widely used in temporary structures such as flood control and cut-off,pier cofferdam,flood fighting and rescue because of its high strength,good impermeability,convenient construction,reusable and low cost.Steel sheet pile cofferdam is an important supporting structure in the process of bridge foundation cap construction,and many achievements have been made in the study of safety and stability analysis of steel sheet pile cofferdam.However,due to the complicated force acting on steel sheet pile cofferdam,the analytical method can not be carried out.At present,the finite element method is widely used in the analysis of steel sheet pile cofferdam.By virtue of ANSYS finite element software,the paper establishes the three-dimensional finite element model of steel sheet pile,purlin,internal support and soil layer,and discusses the construction process of steel sheet pile cofferdam in depth.Considering the external loads such as earth pressure,hydrostatic pressure and flowing water pressure,the key construction procedures such as internal support,bottom-sealing concrete construction,water pumping and mud suction are selected as calculation conditions,and the strength,stiffness and overall stability of steel sheet pile cofferdam structure are analyzed.The deformation and stress of steel sheet pile structure are monitored,and the monitoring results are compared with the numerical simulation results.Combining with steel sheet pile cofferdam of 114# pier,this paper discusses the construction technology and construction process of the whole process from steel sheet pile insertion,reinforcement,mud suction to the casting of bottom covering concrete,and determines reasonable construction process parameters and technical indicators.Influencing factors of 114# steel sheet pile cofferdam are discussed under the hydrostatic and flowing water pressures.It mainly includes the influence analysis of flow velocity,the distribution of flow pressure,the influence analysis of spacing between supports,the influence analysis of Larsen steel sheet piles of different specifications,and the influence analysis of I-shaped steel purlin of different types.The results show that the greater the velocity of flow,the greater the equivalent force of steel sheet pile and the axial stress of purlin and inner support.Larsen steel sheet pile size,especially thickness,increases with Larsen steel sheet pile size,which can greatly reduce the deformation of steel sheet pile and reduce the equivalent force of steel sheet pile,as well as the axial stress of purlin and internal support.The larger I-beam type is selected,the smaller the deformation of steel sheet pile will be,and of course the cost will increase.From the flow pressure distribution form,the influence of triangle distribution is larger,followed by trapezoid distribution,and the influence of inverted triangle is the smallest.The smaller the spacing between the internal supports at the lower part of the steel sheet pile,the smaller the deformation,the smaller the equivalent stress of the steel sheet pile and the axial stress of the purlin and the internal support.Aiming at the problems of steel sheet pile sinking difficulty,deviation of steel sheet pile construction,sinking of existing steel sheet pile together with the steel sheet pile being driven and water leakage between lock ports of steel sheet pile in the construction of steel sheet pile of 114# pier,the causes of each problem are analyzed,and the solutions of each problem are given. |
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