海中软弱地层箱梁现浇支架设计与搭设技术研究

Research on Design and Installation Technology of Bracket for Cast-in-situ Box Girder in Weak Strata in the Sea

以青连铁路跨狡州湾特大桥海中50 m跨度预应力混凝土简支箱梁支架法现浇施工为研究背景,介绍了海中淤泥质、粉细砂地层中箱梁现浇支架的设计布置、受力及稳定性检算方法、支架搭设的施工工艺及控制重点。通过采取增加钢管桩的壁厚,优化钢管的间距布置,使每根钢管基本均勾受力,加大钢管桩的激振力和入土深度,钢管间设置纵横向剪刀撑,加大预压荷栽重量,进行试桩静栽试验等措施,克服了软弱地层中支架不均匀沉降易引起局部失稳和梁体混凝土开裂、大风及波浪冲击力影响支架横向稳定性等不利因素,实现了支架法现浇箱梁的安全、优质、快速施工。总结了一套完整的设计和施工方法,对以后类似工程建设具有一定的借鉴参考意义。

Taking the cast-in-situ construction of 50m span pre-stressed concrete simple-supported box girder bracket for Jiaozhou Bay Bridge of Qing-Lian Railway as the research background,this paper introduced the design and layout of castin-situ box girder bracket in silty and fine sand strata in the sea,the checking method of force and stability,the construction technology and important control points of bracket erection.By taking measures of increasing the wall thickness of steel pipe piles,optimizing the spacing arrangement of steel pipes,making each steel pipe bear the uniform force,increasing the excitation of steel pipe piles and the depth of penetration into soil,setting longitudinal and transverse cross bracing between steel pipes,increasing the weight of preloading and carrying out static load test of trial piles,the safe,high quality and fast construction of cast-in-place box girder with support method was achieved under overcoming unfavorable factors of local instability and cracking of beam concrete caused by the uneven settlement of support in weak strata,and the lateral stability of the support influenced by the strong wind.This paper summarized a complete set of design and construction methods,which has a certain reference significance for similar projects in the future.