Parameter Sensitivity Analysis And Optimal Design Of Deep-water Double-walled Steel Cofferdam

Deep water foundation construction requires a safe and dry platform.The appearance of the double-walled steel cofferdam structure successfully solved the problem of deep water foundation construction.In recent years,many engineering accidents have been related to double-walled steel cofferdams,with severe economic losses and serious casualties.It is of great significance to study the structure of double-walled steel cofferdams.At present,the selection of parameters that affect the mechanical properties of double-walled steel cofferdams is relatively blind in research at home and abroad.There is no systematic study of the influence of various parameters on the mechanical indexes of the main components of double-walled steel cofferdams;at the same time,there is no specific double-walled Steel cofferdam design specifications,so in the design of double-walled steel cofferdams,a conservative approach is often taken,which causes a lot of waste of resources.Therefore,it is necessary to analyze the sensitivity of the structural parameters of the deep-water double-walled steel cofferdam and optimize the design.Based on the actual engineering of the deep-water double-walled steel cofferdam of the Chongzuo Xizuojiang Bridge in Chongzuo City,Guangxi Province,this paper divides the construction of the deep-water double-walled steel cofferdam of the Chongzuo Xizuojiang Bridge into three working conditions,namely,there is no water in the cofferdam,Three layers of internal support in the cofferdam;water injection in the cofferdam to the second layer of internal support,remove the third layer of internal support;water injection in the cofferdam to the first layer of internal support,remove the second layer of internal support.First of all,through theoretical analysis to optimize the arrangement of measuring points,rational deployment of strain gauges,real-time monitoring of structural strain stress during construction of the double-walled steel cofferdam of the Chongzuo Xizuojiang Bridge to obtain the stress of each working condition.Secondly,the finite element software ANSYS is used to establish and calculate the doublewalled steel cofferdam model in combination with the actual load and boundary conditions of the project,and the connection of different elements in the model is reasonably processed,compared with the measured stress results,and the rationality of the finite element analysis is verified to correct the double In the wall steel cofferdam model,it is proposed that setting the load partial coefficient to 1.15 to 1.20 can better simulate the mechanical properties of the actual structure.Using local sensitivity analysis method combined with modified double-wall steel cofferdam model,the parameter sensitivity analysis of the cofferdam structure was carried out.The parameters were selected as the structural parameters of the deep-water double-wall steel cofferdam,which were the horizontal spacing of the bulkhead,horizontal ring plate and horizontal,respectively.Vertical spacing of truss,wall thickness,horizontal spacing of internal support.The results show that the mechanical properties of the wall are sensitive to the changes in the horizontal spacing of the bulkheads,the vertical spacing of the horizontal ring plates and horizontal truss,and the thickness of the wall panels;the overall mechanical properties of the structure are sensitive to the changes in the horizontal spacing parameters of the internal supports.Finally,the key mechanical parameters that are sensitive to these parameter changes are selected as mechanical constraints,combined with constraints such as economic efficiency and the size of the construction space in the cofferdam,the horizontal spacing of the bulkhead,the vertical spacing of the horizontal ring plate and the horizontal truss,and the siding Four structural geometric variables of thickness and horizontal spacing of inner support are optimized,and the optimized design value and range of each component are given.