新建安九铁路鳊鱼洲长江大桥5号墩基础施工防护技术

新建安九铁路鳊鱼洲长江大桥主桥为(50+50+224+672+174+50+50+50)m钢箱混合梁斜拉桥,5号墩承台临近九江侧防洪大堤边坡。为了确保5号墩基础施工过程中大堤的安全,大堤采用双排钻孔桩+冠梁+系梁+高压旋喷桩及分层注浆的防护方案进行防护,利用三维有限元法对防护结构的变形、内力、抗滑移稳定性进行了分析,结果均满足要求。通过对大堤设计合理的防护结构并采取合适的施工措施,对5号墩桩基施工采取溶洞区防塌孔及优化钻进方式的施工措施,以及承台施工围堰采取安全有效的吸泥控制及河床防冲刷等施工措施,减少了对大堤的干扰及破坏,确保了大堤的安全。在施工过程中对大堤进行了实时监测,大堤变位满足要求,大堤和基础施工安全。

Techniques Used to Protect Foundation Construction of Pier No.5 of Bianyuzhou Changjiang River Bridge on Newly-Built Anqing-Jiujiang Railway

The main bridge of Bianyuzhou Changjiang River Bridge on the newly-built Anqing-Jiujiang Railway is a steel box-concrete hybrid girder cable-stayed bridge with eight spans of 50,50,224,672,174,50,50,and 50 m.The pile cap of the pier No.5 is near to the slope of the flood embankment on the Jiujiang side.To assure the safety of the embankment during the construction of the foundation of pier No.5,a protection structure consisting of double-rowed bored piles,cap beams,tie beams and high pressure jet-grouted piles was built,and grout was injected layer by layer.The finite element method was used to analyze the deformation,internal force and anti-slippage stability of the protection structure,and the results met the requirements.By designing rational protection structure to the embankment and taking proper construction measures,the safety of the embankment was guaranteed.During the construction of the pile foundation of pier No.5,precautions were taken and the drilling method was optimized to prevent perforation collapse in the karst caves region.Slurry was efficiently discharged and proper anti-scour method was used to protect the river bed,to reduce the disturbance and damage to the embankment.The embankment was monitored during the construction process.The deformation of the embankment met the requirements,and both the embankment and the foundation were safe during the construction.