跨越既有线路曲线钢箱梁顶推施工有限元分析

钢箱梁顶推施工技术是桥梁建设中常见的施工技术之一,而小半径曲线钢箱梁的直线顶推施工是钢箱梁顶推施工中比较特殊的一种,因为由于钢箱梁小半径的特殊性,在进行一定量的顶推之后都需要对钢箱梁进行平面内的旋转调整使其中心线与设计中心线重合。而在调整之前钢箱梁前后端的曲线段悬挑会使钢箱梁处于偏载状态,影响钢箱梁整体的受力与变形。鉴于此,以长平枢纽互通A匝道桥为例,对小半径曲线钢箱梁的顶推施工进行施工模拟,来保证顶推施工的安全性。模拟结果表明,在整个曲线顶推过程中,最不利状态下的最大应力、变形、支反力处在3个不同的危险工况下,最大应力σ_(max)=137.9 MPa≤[σ]=210 MPa,发生在支撑位置,满足受力要求;最大变形u_(max)=-98.033 mm,钢导梁前端设470 mm上墩措施,导梁竖向挠度满足施工要求;最大支反力F_(max)=236.0 t,需对支架结构临时措施进行局部加强,防止产生不理想应力及变形。

Steel box girder jacking construction technology is one of the common construction technologies in bridge construction,and the straight line jacking construction of small-radius curved steel box girder is a relatively special one in steel box girder jacking construction,because due to the particularity of steel box girder small radius,after a certain amount of jacking,it is necessary to adjust the steel box girder in-plane rotation so that its center line coincides with the design center line.However,before adjustment,the cantilever of the curved sections at the front and rear ends of the steel box girder will put the steel box girder in a biased load state,which will affect the overall force and deformation of the steel box girder.In view of this,taking the A ramp bridge of Changping Junction Interchange as an example,the construction simulation of the jacking construction of small-radius curved steel box girders is carried out to ensure the safety of the jacking construction.The simulation results show that during the entire curve pushing process,the maximum stress,deformation,and support reaction force under the most unfavorable state are under three different dangerous working conditions.The maximum stress σ_(max)=137.9 MPa≤[σ]=210 MPa,which occurs at the support position and meets the stress requirements;the maximum deformation u_(max)=-98.033 mm,a 470 mm upper pier measure is set at the front end of the steel guide beam,and the vertical deflection of the guide beam meets the construction requirements.The maximum support reaction force F_(max)=236.0 t,so temporary measures for the support structure need to be locally strengthened to prevent undesirable stress and deformation.