重载铁路桥梁支座顶升更换施工技术

Construction Technology of Lifting and Replacing Railway Bridge Bearings

在深厚软土地区,桥下堆载与重车通行易引起桥墩沉降及倾斜,致使桥梁支座纵向位移超限。以大丽铁路某特大桥为工程依托,开展铁路桥梁支座顶升更换施工技术的应用研究。考虑运营铁路天窗期施工作业时间短、作业面狭窄、涉及专业施工内容多和安全风险高等特点,提出了用两台千斤顶同步顶升更换既有铁路桥梁支座的方案,并计算分析了千斤顶的选取、桥墩局部承压和梁缝缩小值等技术参数。结果表明:(1)采用两台DYG200型号的千斤顶,单台起重量2 000 k N,满足顶升重量要求;(2)既有桥墩顶帽C25钢筋混凝土局部承受压应力为12. 526 MPa,局部压力为885 k N,满足规范要求;(3)调整支座的梁体顶升高度为20 mm,更换支座的梁体顶升高度为88~92 mm,顶升高度满足现场施工需要;(4)顶升更换既有铁路桥梁支座施工技术对铁路桥梁支座纵向位移超限病害控制效果明显。

Diseases such as settlement and tilt of bridge piers were easy to occur under bridge heaped load and heavy vehicle traffic in deep soft soil area, which would result in the longitudinal displacement over-limit disease of the bridge bearing. Based on a super large bridge in DaLi Railway, the application research on construction technology of replacing bearing by jacking for heavy haul railway bridge was carried out. Considering the characteristics of short construction time, narrow working space, numerous professional construction content and high safety risk in maintenance time of existing operating railway, a scheme of replacing existing railway bridge bearings with two jacks jacking-up synchronously was put forward, and the technical parameters such as the selection of jacks, local bearing capacity of piers and reduction value of beam crevice were calculated and analyzed. The results show that:(1) Two DYG200 jacks with lifting weight of 2000 kN per one can meet the jacking-up weight requirements of bridge;(2) The local compressive stress of C25 concrete in the existing pier cap is 12.526 MPa, and the local pressure is 885 kN, which can both meet the requirements of the code;(3) The jacking-up height of girder whose supports would be adjusted is 20mm, and the jacking-up height of girder whose supports would be replaced is from 88 mm to 92 mm. The jacking height can meet requirements of field construction;(4) The construction technology of replacing bearing for existing railway bridge by jacking has obvious effect on controlling the longitudinal displacement over-limit disease of railway bridge bearings.