Study On Mechanical Behavior And Green Construction Technology Of Assembled Composite Plate Cofferdam

With the continuous development of bridge engineering,the use of cofferdam structure is more and more common,but the support system of traditional cofferdam and the construction technology are complex,which has certain requirements for geological conditions.For this reason,the fabricated steel-concrete-steel sandwich composite cofferdam are put forward,and the underwater concrete foundation is used to fix the composite cofferdam,so that it can be constructed in deep water,avoiding the problems of hard soil layer in the construction site and difficult to drive into the traditional cofferdam.The composite cofferdam has brought into the compressive properties of concrete and the tensile properties of steel,making full use of the materials,and has a broad application prospect.The steel-concrete-steel sandwich composite plate was the main stress component of the cofferdam.In order to meet the connection requirements of the composite cofferdam,three new types of prefabricated composite plate and nine connection methods were proposed.The two ends of the composite plate were made into special shape,the flange plate was welded on the outside of the steel plate,and the assembly was carried out through the friction type connection of high-strength bolts and the internal and external lock catches,and the construction steps were put forward.Based on the differential equation of the axial force between steel plate and concrete,the calculation formula of the axial force between steel plate and concrete under the triangle uniform load was derived.The finite element analysis software ABAQUS was used to simulate the cofferdam.The influence of different stud spacing and diameter on stud stress and the relative deformation between steel plate and concrete was analyzed;the influence of working condition load,concrete grade and thickness,and steel plate thickness on Cofferdam deformation and stress was analyzed.The results showed that the increase of stud spacing and diameter increased stud stress and the relative deformation between steel plate and concrete slab;when stud diameter was reduced to 30mm or the spacing was increased to 1000mm,stud yield stress reached 235MPa;when cofferdam internal water level dropped to the lowest,the deformation and stress were the largest and the long side deformation was 9mm larger than the short side;cofferdam deformation,steel plate stress and mid span mixing the concrete stress decreased with the increase of the thickness of the concrete slab;the deformation of the cofferdam,the steel plate stress and the concrete stress along the side length increased with the increase of the thickness of the steel plate.Based on the fabricated composite plate cofferdam and combined with the green construction management measures,the specific color filtering construction technical measures were proposed.The green construction evaluation index system of cofferdams was established.The weight of green construction index of cofferdams was assigned by using analytic hierarchy process.The index was sorted according to the importance degree.The green construction of cofferdams was evaluated by using fuzzy comprehensive evaluation method.The evaluation opinions of experts were summarized systematically and comprehensively to reflect the advantages and disadvantages of green construction of cofferdams.