Study On Mechanical Behavior Of Double-wall Steel Cofferdam On Foundation Of Yongxiu Bridge

The double-wall steel cofferdam support is used in the construction of the main bridge of Changjiu Intercity Yongxiu Bridge.In the upper reaches of Xiushui River,Zhelin Reservoir,the largest reservoir in Jiangxi Province,is near the construction site.During the construction period,the water level will rise by 2 m after the opening of the reservoir.In order to ensure the safety of deep water foundation construction of Yongxiu Bridge,the double-wall steel cofferdam is analyzed by combining traditional theoretical calculation with numerical simulation.In this thesis,the stress state of double-wall steel cofferdam is monitored by stress monitoring method during the construction process.The stress state of double-wall steel cofferdam is calculated by plane simplified theoretical calculation method and ANSYS three-dimensional simulation under the most disadvantageous condition before construction.The main contents and conclusions are as follows:(1)Through the theoretical calculation,the stress analysis of the internal support,vertical rib,wall slab and partition board of the double-wall steel cofferdam is obtained,and the stress of each component is met.(2)The three-dimensional numerical model analysis shows that the displacement of the double-walled steel cofferdam,the wall stress,various rods and internal supports meet the design requirements.It is also found that the double wall filled with concrete or sand below the top line of the platform can improve the overall structural rigidity,reduce the maximum stress and improve the safety.(3)The stress changes of the outer panel,the vertical stiffening angle steel and the inner support of double-wall steel cofferdam under the most unfavorable conditions are monitored,and the monitoring results are analyzed.Comparing the theoretical calculation value,the simulated value and the measured value,it is found that the simulated value is closer to the measured value.The theoretical calculation fails to give full play to the function of composite structure,which leads to the failure of the mechanical properties of materials.