太洪长江大桥隧道式锚碇设计  

Design of Tunnel Anchorage of Taihong Changjiang River Bridge

作　　者：郑升宝 刘小辉 陈奉民 邓耀 ZHENG Sheng-bao;LIU Xiao-hui;CHEN Feng-min;DENG Yao(China Railway Changjiang Traffic Design Group Co. ,Ltd. ,Chongqing 401121,China)

机构地区：[1]中铁长江交通设计集团有限公司,重庆401121

出　　处：《世界桥梁》2022年第1期19-25,共7页World Bridges

基　　金：重庆市交通局科技项目(16KJ04)。

摘　　要：太洪长江大桥主桥为跨径808 m单跨简支钢箱梁悬索桥,南川岸采用隧道式锚碇,锚碇位于极软岩中,岩石天然饱和抗压强度为4.49 MPa,围岩级别为Ⅴ级,地质条件差。针对锚碇工程地形、地质条件,通过在主索鞍处向外旋转边跨主缆及隧道式锚碇轴线角度2°,解决了隧道式锚碇浅埋以及2个锚塞体间距过小的问题;进行多参数比选,隧道式锚碇前、后锚面尺寸(宽×高)分别取13 m×13 m、18 m×19 m,顶部为圆弧形,锚塞体最终长度为58 m,前、后锚室长度分别为35 m、3.8 m。依据规范计算得到隧道式锚碇锚塞体抗拔安全系数为4.3,通过岩土专项试验和数值模拟计算得到围岩稳定安全系数约为6.0,分别满足规范不应小于2.0和4.0的要求。施工时,采用围岩损伤控制和光面爆破相结合的开挖技术,以减少隧洞围岩损伤,锚塞体采用强格栅钢架防护形式,以加强锚塞体和围岩整体受力。The main bridge of Taihong Changjiang River Bridge is a simply-supported steel box girder suspension bridge with a single span of 808 m.The Nanchuan-side anchorage is a tunnel anchorage that is located in poor geological environment,where the compressive strength of fully-saturated rock is 4.49 MPa and the stability of the surrounding rock is graded V.The shallow burying depth of the tunnel anchorage and small spacing between the two anchor plugs posed great challenges to the construction of main cables and the anchorage itself.To address this issue,the side-span main cables and the axis of the tunnel anchorage were rotated outwardly by 2°at the saddles to facilitate the construction.As per parametric comparison,the tunnel anchorage obtains a circular arc roof,with the front and rear anchor surfaces of 13 m(width)×13 m(height)and 18 m(width)×19 m(height),respectively.The anchor plugs are 58 m long,and the front and back anchor chambers are 35 m and 3.8 m long,respectively.Based on the code,the calculated safety factor of uplift resistance is 4.3(greater than the value of 2.0 given in code).The stability safety factor of surrounding rock gained from special geotechnical test and numerical simulation is 6.0(greater than the value of 4.0 given in code).During the tunnel excavation,measures were taken to control the damage of surrounding rock,and smooth blasting was also applied for the same purpose.To strengthen the integral load bearing performance of the anchor plugs and surrounding rock,the strong grid steel frame was used for shoring and protection.

关 键 词：悬索桥 隧道式锚碇 极软岩 岩土专项试验 数值模拟 开挖 防护 结构设计 

分 类 号：U443.24[建筑科学—桥梁与隧道工程] U442.5[交通运输工程—道路与铁道工程]