Study On The Stress Analysis Of Trestle Super-long Steel Pipe

As a kind of temporary structure,trestle has the characteristics of a temporary service functions concurrently at the same time.As more and more sea-crossing and river-crossing bridges are being built,as a kind of auxiliary construction of temporary measures,temporary construction of trestle is applied more and more in the engineering construction.Due to the quick speed of dismantling,convenient and able to reuse,trestle construction is applied to bridge construction,port engineering and dam engineering increasingly,security and economy problem is paid more and more attention now.Construction process of temporary trestle is very complicated,and action law of the axial force,displacement and stress response of steel pipe pile under the stress is unclear,responses of each steel pipe pile as the hoisting machinery load stress moves during operating process are not identical,it is necessary to simulate these complicated process through the numerical simulation.Based on the evaluation of the geological conditions,this article first introduced project profile of the Lingguangou trestle and then effects of stress as well as the factors affecting the stability of long steel pipe pile of the long steel pipe pile pier in construction stage and using stage were studied,and analysis of change rule of stability of super long steel pipe piles under the action of the these factors was made,finally the quantitative analysis of influence degree of the influence factors on the stability of long steel pipe pile was analyzed,related conclusions were as follows:(1)The change of steel pipe pile axial force is relatively significant during construction process,mobile crane load has large effect on axial force of piles,wind and water load have great influences on the axial force of steel pipe pile,what makes tensile stress appear in some areas of steel pipe pile.The application of crane load and its position have little influence on lateral displacement of bridge panel and pile,while the wind and water load applied have great influence on lateral displacement of bridge panel and pile,and the longer the pile,the lateral displacement cross the bridge of top pile bigger.The maximum equivalent stress is far lower than the allowable value of material and buckling damage will not occur during the construction process.(2)During the using stage,when crane load is located in the middle of the bridge span,there is a large influence on axial force on both sides of the group of pile body and the other group of axial stress of pile influence degree decreases as the distance increases.When the crane load directly applied at the tail,the department of axial stress of pile increased,and the adjacent side group of axial stress of pile fell more obvious.When the crane load is located in different positions,it has little effect on displacement of the pile cross bridge,displacement of pile in lateral bridge direction is more affected by water and wind load.When crane load is located in the middle of the bridge span,the biggest displacement values along the bridge emerge on both sides at the top of the pile group.The application of crane load and its position are the key factor steel pipe pile displacement along the bridge.(3)As for the maximum horizontal displacement of the steel pipe pile,improving the capacity of soil elastic modulus,pile length into the soil and pile lateral spacing will make maximum horizontal displacement of the steel pipe pile first sharply decline,and then slowly reduce.While pile length increases,maximum horizontal displacement of steel pipe pile first slowly rises,and then sharply increases.While steel pipe pile diameter increases,the maximum horizontal displacement of steel pipe pile only has a modest growth.As for the steel pipe pile maximum principal stress,change rule of steel pipe pile maximum principal stress as influence factors change is less obvious.(4)Small changes of pile length or pile diameter values will make the stability coefficient of steel pipe pile produces significant change,pile length or pile diameter are sensitive factors as to the stability of steel pipe.Soil modulus and pile depth into the soil are less sensitive factors,while pile spacing is the least sensitive factors.(5)Based on MATLAB neural network toolbox and compared the numerical simulation results with BP neural network prediction results,the method of applying neural network to predict the stability of pier steel pipe pile is put forward,which provides the reference for predicting the stability of steel pipe pile analysis.