| Steel sheet pile cofferdam has the characteristics of high strength,easy to be driven into the hard soil,good water resistance,can be constructed in deep water,and can be recycled repeatedly,and can form various shapes of cofferdam as required,is widely used in the construction of water conservancy projects.As a new structural form,double-row steel sheet pile cofferdam can not only effectively improve the stability and deformation resistance of single-row steel sheet pile cofferdam,and in terms of capital investment and single-row steel sheet pile cofferdam is almost the same as the difference,also without internal support,and increase the construction of the working face,so it has high application value.This paper takes the double-row steel sheet pile longitudinal water-retaining cofferdam of Wushahe pumping station in Nanchang city as the research object,analyzes the stress deformation and stability of double-row steel sheet pile cofferdam under construction and operation conditions,and discusses the distribution law of earth pressure in double-row steel sheet pile cofferdam.This paper analyzes the influence of factors such as the spacing between steel sheet piles,the horizontal and vertical arrangement spacing of tie rods,and the range of soil reinforcement area between piles on the stability of cofferdam,and discusses the sensitivity of the stress deformation and stability of cofferdam to the change of design parameters based on the theory of redundancy.A double row steel sheet pile cofferdam structure without soil filling is presented and calculated.Specific research contents are as follows:(1)The physical and mechanical properties of the soil filled between double-row steel sheet piles were experimentally studied by means of sieve test,liquid-plastic limit test,compaction test and quick shear test,and the change law of the shear strength index under different compacting degrees was emphatically studied,which provided a basis for the design of cofferdam structure.(2)The two-dimensional stress and deformation analysis of three typical cofferdam sections under construction and operation conditions is carried out,and the axial force values of steel sheet pile deformation,internal force and pull bar of cofferdam structures of each section under construction and operation conditions are obtained.At the same time,according to the drydock design code CB/t8524-2011,it is suggested that the inner and outer row steel sheet piles should be separated into separate single row steel sheet piles,according to the single row sheet pile model to calculate the stress of steel sheet pile,the stress deformation of steel sheet pile and the axial force of pull rod are calculated by using the software of lizhengshen deep foundation pit,and the double-row sheet pile cofferdam is regarded as the gravity retaining wall,and the anti-overturning and anti-sliding stability of double-row sheet pile cofferdam is analyzed.The results of comparative analysis show that the shear force,bending moment and axial force of steel sheet pile calculated by the proposed method are larger than those calculated by the finite element software,while the horizontal displacement of steel sheet pile structure is smaller than that calculated by the finite element software.The deformation of steel sheet pile,the strength of steel sheet pile,the axial force of pull bar and the anti-overturning and anti-sliding safety coefficient of cofferdam in all sections can meet the requirements of design and specification.(3)the distribution law of earth pressure in the cofferdam filled with double-row steel sheet pile is analyzed and compared with the Rankine active,passive and static earth pressure.(4)Different influence factors are studied by using three-dimensional finite element software(rod different elevation,tie rod,the horizontal spacing of double row between the steel sheet pile spacing,pile foundation reinforcement zone)of double row of steel sheet pile cofferdam all the stress,deformation and stability under the condition,and combining the theory of redundancy analysis stress deformation of the cofferdam and the stability of the sensitive degree of various design parameters,reasonable selection of various parameters reference and Suggestions are put forward.(5)A double-row steel sheet pile cofferdam structure without internal soil is put forward,and the stress,deformation and stability of the cofferdam during the whole process of construction and operation are analyzed.The analysis results show that the cofferdam meets the design requirements,and the structure provides a reference for the design of this project and similar projects. |
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