马鞍山长江大桥南锚沉井下沉关键技术研究

马鞍山长江大桥南锚碇采用沉井基础，沉井入土深度超过50m，其施工采用“3次接高，3次下沉”的工艺：第1次下沉采用降排水措施，第2次下沉采用半排水措施，第3次下沉采用不排水措施。在沉井第3次下沉过程中，开启空气幕助沉，显著加快了下沉速度。沉井下沉期间，采用综合监控手段，保证了沉井顺利、精确下沉。实践证明，该桥所采用的沉井下沉方案科学合理，下沉到位后沉井几何姿态良好。

Research on Key Techniques for Subsidence of South Anchor Open Caisson of Maanshan Yangtze River Bridge

Open caisson foundation is adopted for south anchor of Maanshan Yangtze River Bridge with the buried depth over 50 m, and its construction adopts technology of ＂jointing for three times and subsidence for three times＂： the first subsidence employs dewatering and drainage, the second subsidence half- drainage and the third subsidence no drainage. During the third subsidence of the open caisson, air curtain is started to assist subsidence, speeding up subsidence remarkably. During subsidence of the open caisson, integrated monitoring means are adopted to guarantee smooth and accurate subsidence of the open caisson. The practice proves that the subsidence scheme of the open caisson adopted for the bridge is scientific and reasonable, and geometric profile of the open caisson after subsidence is in place is perfect.