高铁墩顶转体悬浇连续梁支座沉降处置技术研究

A Study of the Settlement-Treating Techniques for Pedestals of the Pier-Top-Rotation Cantilever-Poured Continuous Beam of High-Speed Railways

高速铁路连续梁合龙前后中墩支座由于安装工艺控制缺陷,可能会引起不均匀沉降,而随着后期的二期恒载以及活载的逐步施加,不均匀沉降会不断增加,导致支座底板发生严重塑性变形,并在连续梁内产生附加的扭转应力,使边支墩横向两支座的竖向反力产生明显差异,甚至导致一侧边支座在活载作用下出现脱空的极端现象。基于实际工程案例,研究了该病害对梁体受力的不利影响,并对病害的处理措施进行了分析。对于大型支座,应优化底部砂浆的灌注工艺,确保砂浆层的厚度不小于25mm。采用力控制/位移监测的同步提升方法可有效解决支点反力不均、支座严重沉降变形等病害。

Before and after the two sections of a continuous beam of a high speed railway is joined,uneven settlement of the pedestal of the mid-pier might happen as a result of the defects in the control of the fixing process,and with the gradual increase in the 2 nd-term loads and live loads,the uneven settlement tends to increase continuously,which may cause the serious plastic deformation of the baseplate of the pedestal,and besides,add twisting stress to the continuous beam,which may cause the vertical reaction of the two transverse pedestals of the side supporting pier to be remarkably different,and even cause one of the two side supporting pedestals to be unable to prop up the beam under the action of live loads.Upon the basis of practical engineering examples,the unfavorable effects of the defect on the stress of the beam body are studied,with its treating measures analyzed.With largetype pedestals,the pouring process for the bottom mortar should be optimized so as to ensure that the depth of the mortar be no less than 25 mm.With the synchronous promotion method of force control and displacement monitoring adopted,the uneven reaction of the supporting points,and the serious settlement,deformation and other defects of the supporting pedestals may be effectively overcome.