温州瓯江北口大桥中塔钢沉井定位着床技术

温州瓯江北口大桥主桥为(215+2×800+275)m的三塔双层钢桁梁悬索桥,中塔采用沉井基础,沉井平面尺寸为66m×55m,高68m,其中,钢沉井高59m。为实现钢沉井的精确定位着床,采用锚墩+重力锚相结合的定位技术,在水流流速和风速较小的时间段,采用向井壁和隔舱内快速注水实现钢沉井快速着床。在钢沉井初定位、精定位及注水着床期间,运用实时监测技术,对钢沉井几何姿态及底面应力进行了实时监测,并及时对沉井偏位、扭转等采取纠偏措施。结果表明,着床后钢沉井中心点顺桥向偏北侧8.0cm,横桥向偏上游侧21.9cm,平面扭转角为-0.24°,钢沉井几何姿态控制良好。

Positioning and Landing of Steel Caisson of Intermediate Pylon of Oujiang River North Estuary Bridge in Wenzhou

The main bridge of Oujiang River North Estuary Bridge is a three-tower steel truss girder suspension bridge with two layers of decks and with spans of 215,2×800 and 275 m.The intermediate tower stands on steel caisson foundation measuring 66.0 m by 55.0 m,and 68.0 m in total height.To realize the accurate positioning and landing of the steel caisson,the positioning technique of combined use of anchor piers and gravity piers was adopted.At the time when both the flowing speed of water and wind speed were small,water was pumped and quickly injected of into the caisson wall and chambers to realize the rapid landing of steel caisson.In the process of initial positioning,accurate positioning and landing with assistance of filling water of the steel caisson,the geological position and stresses in the base of the steel caisson were monitored in real time,and the offsetting and torsion of the caisson had got timely correction.The results show that the central point of the steel caisson after landing deviates about 8.0 cm towards the north along the bridge length,and 21.9 cm towards the upstream side along the bridge width.The plan torsion angle was-0.24°and the geometrical shape of the steel caisson was under well control.