大跨度地锚式斜拉桥换索施工技术
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摘要
郧县汉江大桥为(86+414+86)m地锚式预应力混凝土斜拉桥,每塔两侧各布置2×25根斜拉索。检测发现:斜拉索索力和设计理论状态误差较大,PE护套损伤,钢丝锈蚀严重,斜拉索系统属于四类部件。为确保桥梁结构的长期安全,结合该桥斜拉索体系病害情况,运用等强度换算原理,设计新斜拉索[采用镀锌平行钢丝、PES(HD)低应力全防腐索体、全防水结构等多项技术],替换全桥旧斜拉索。斜拉索更换顺序为病害斜拉索优先,单塔对称、双塔反对称,由长索到短索的原则进行更换。有限元结果表明,在整个换索过程中,斜拉索、主梁和桥塔结构变形、应力和强度验算均能满足规范要求。换索施工工序为旧索放张→旧索拆除→新索安装与张拉→索力调整。通过优化施工工艺,长索单塔换完后,2个点4根索同时更换,将换索工期降低到120d,极大地缩短了施工工期。
The Hanjiang River Bridge in Yun County is an earth-anchored prestressed concrete cable-stayed bridge with spans of 86,414 and 86m.To each side of the pylon,a number of 2×25stay cables are tensioned.The inspections found that there existed big difference between the stay cable forces and the designed theoretical force conditions,PE sheaths had damages,corrosion of steel wires was severe,and the stay cable system was classified to the fourth grade of deterioration.To ensure the long-term safety of the bridge structure,all the original stay cables of the bridge must be replaced.In accordance with the deterioration condition of the stay cable system of the bridge,the new stay cables were designed following the equal intensity conversion principle.The new stay cables adopt the galvanized parallel steel wires,and the techniques,like PES(HD)low stress and fully corrosion-protected system and fully waterproof structure,are used.The replacement sequence of stay cables follows the principle of replacing the deteriorated cables first,symmetrical replacement for single pylon,inversely symmetrical replacement for double pylons,and proceeding from long cables to short cables.The finite element results show that the structural deformation,stresses and strength of stay cables,main girder and pylons checked during the cable replacement process could meet the code requirements.The cable replacement construction follows the procedure from de-tensioning of original cables,through original cables removing and new cables installation and tensioning,to new cable force tuning.The construction techniques were optimized,once the replacement of long cables in the single pylon was complete,four cables at two points were replaced in parallel,shortening the replacement schedule to 120 dand greatly reducing the construction time.
The Hanjiang River Bridge in Yun County is an earth-anchored prestressed concrete cable-stayed bridge with spans of 86,414 and 86m.To each side of the pylon,a number of 2×25stay cables are tensioned.The inspections found that there existed big difference between the stay cable forces and the designed theoretical force conditions,PE sheaths had damages,corrosion of steel wires was severe,and the stay cable system was classified to the fourth grade of deterioration.To ensure the long-term safety of the bridge structure,all the original stay cables of the bridge must be replaced.In accordance with the deterioration condition of the stay cable system of the bridge,the new stay cables were designed following the equal intensity conversion principle.The new stay cables adopt the galvanized parallel steel wires,and the techniques,like PES(HD)low stress and fully corrosion-protected system and fully waterproof structure,are used.The replacement sequence of stay cables follows the principle of replacing the deteriorated cables first,symmetrical replacement for single pylon,inversely symmetrical replacement for double pylons,and proceeding from long cables to short cables.The finite element results show that the structural deformation,stresses and strength of stay cables,main girder and pylons checked during the cable replacement process could meet the code requirements.The cable replacement construction follows the procedure from de-tensioning of original cables,through original cables removing and new cables installation and tensioning,to new cable force tuning.The construction techniques were optimized,once the replacement of long cables in the single pylon was complete,four cables at two points were replaced in parallel,shortening the replacement schedule to 120 dand greatly reducing the construction time.
引文
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[2]湖北省交通规划设计院股份有限公司.湖北省郧县汉江公路大桥结构运营分析及调治方案报告[R].武汉,2002.
[3]湖北省公路工程咨询监理公司.G209郧县汉江大桥技术状况评定报告[R].武汉,2014.
[4]高洪波,丁志凯.某悬索斜拉索组合式跨越管桥的换索设计[J].桥梁建设,2017,47(2):95-99.
[5]王海良,谢佳飞.某大桥斜拉索病害原因分析及建议[J].铁道标准设计,2005(10):67-69.
[6]张卓杰,王荣辉,甄晓霞,等.平行钢绞线斜拉索索力测试方法评价[J].桥梁建设,2016,46(2):42-47.
[7]李鸥,侍刚,王波,等.运营期桥梁斜拉索的技术状况检测[J].世界桥梁,2017,45(4):79-83.
[8]马明.桂丹立交特大桥主桥桥式方案研究[J].铁道勘察,2017(4):107-111.
[9]张新军,姚美.大跨度部分地锚式斜拉桥抗风稳定性参数研究[J].桥梁建设,2016,46(3):23-28.
[10]吴小斌,杜俊,李东辉.九江二桥平行钢丝斜拉索牵引入锚施工技术[J].世界桥梁,2014,42(3):34-38.
[11]左宏献,张士轩,付东.黄冈公铁两用长江大桥斜拉索安装技术[J].桥梁建设,2013(2):28-32.