跨越既有線路曲線鋼箱梁頂推施工有限元分析

摘 要：鋼箱梁頂推施工技術(shù)是橋梁建設(shè)中常見的施工技術(shù)之一，而小半徑曲線鋼箱梁的直線頂推施工是鋼箱梁頂推施工中比較特殊的一種，因為由于鋼箱梁小半徑的特殊性，在進行一定量的頂推之后都需要對鋼箱梁進行平面內(nèi)的旋轉(zhuǎn)調(diào)整使其中心線與設(shè)計中心線重合。而在調(diào)整之前鋼箱梁前后端的曲線段懸挑會使鋼箱梁處于偏載狀態(tài)，影響鋼箱梁整體的受力與變形。鑒于此，以長平樞紐互通A匝道橋為例，對小半徑曲線鋼箱梁的頂推施工進行施工模擬，來保證頂推施工的安全性。模擬結(jié)果表明，在整個曲線頂推過程中，最不利狀態(tài)下的最大應(yīng)力、變形、支反力處在3個不同的危險工況下，最大應(yīng)力σmax=137.9 MPa≤[σ]=210 MPa，發(fā)生在支撐位置，滿足受力要求;最大變形umax=-98.033 mm，鋼導(dǎo)梁前端設(shè)470 mm上墩措施，導(dǎo)梁豎向撓度滿足施工要求;最大支反力Fmax=236.0 t，需對支架結(jié)構(gòu)臨時措施進行局部加強，防止產(chǎn)生不理想應(yīng)力及變形。

關(guān)鍵詞：鋼箱梁;應(yīng)力;模擬;頂推;變形

中圖分類號：U445.4 文獻標(biāo)志碼：A 文章編號：2095-2945（2024）30-0044-04

Abstract： 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 σmax=137.9 MPa≤[σ]=210 MPa， which occurs at the support position and meets the stress requirements; the maximum deformation umax=-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 Fmax=236.0 t， so temporary measures for the support structure need to be locally strengthened to prevent undesirable stress and deformation.

Keywords： steel box girder; stress; simulation; pushing; deformation

曲線鋼箱梁的頂推施工一直是工程領(lǐng)域下的研究熱點，魏小強等[1]針對橫琴口岸蓮花大橋小半徑曲線橋鋼箱梁頂推施工進行了研究，分析了現(xiàn)場施工條件不便，鋼箱梁與板結(jié)構(gòu)、改造工程存在上下立體交叉作業(yè)，無法正常施工的現(xiàn)狀，創(chuàng)造性地提出“差速頂推”施工工藝，保證箱梁內(nèi)外側(cè)運動角速度相同，線速度不同。通過控制內(nèi)外側(cè)線速度的比例，使鋼箱梁按設(shè)計線路移動，完美解決了施工時跨越橋梁、道路的難題。……