五峰山长江特大桥沉井基础施工监控

五峰山长江特大桥主桥为主跨1 092m的钢桁梁公铁两用悬索桥,北锚碇采用100.7m×72.1m×56m的沉井基础。该沉井首节采用钢壳混凝土结构、其余9节采用钢筋混凝土结构,采用“三次接高、三次下沉”的方案施工。为及时掌握沉井下沉施工过程中的几何姿态及受力情况,建立实时在线监测系统,对沉井几何姿态、沉井结构应力及沉井刃脚土压力进行自动化监测,基于监测数据及时进行沉井下沉控制。结果表明:下沉过程中沉井测点高差和倾斜度均在限值内,沉井挠度基本在20mm限值内,沉井几何姿态较好;沉井混凝土及钢结构测点的实测应力基本在限值范围内,沉井刃脚各测点的土压力均控制在1.20MPa限值内,沉井结构受力良好。

Monitor and Control for Caisson Foundation Construction of Wufengshan Changjiang River Bridge

The main bridge of the Wufengshan Changjiang River Bridge is a suspension rail-cum-road bridge with a main span of 1 092 m and a structure of steel truss girder, and the caisson foundation with sizes of 100.7 m×72.1 m×56 m is adopted for the north anchorage. The caisson consists of a concrete-filled steel box for the first section and reinforced concrete structures for the rest nine sections. The plan of "height extending for 3 times and sinking for 3 times" is used in the caisson construction. In order to timely know the geometric attitude and stress conditions of the caisson in construction stages, a real-time online monitoring system is established to automatically survey the geometric attitude, stresses of caisson structure, and soil pressure of blade foot of caisson. Meanwhile, the caisson sinking is timely controlled according to the monitoring data. The results show that the elevation difference and inclination of the caisson are all within the limited values, the deflections of caisson are all within the limited value 20 mm, and the geometric attitude of caisson can meet the requirements of controlled parameters. The measured stresses of concrete and steel structures are basically within the limited values and the measured soil pressures are all controlled within the limited value 1.20 MPa. It is revealed that the caisson structure is in good force condition and can meet the requirements of controlled parameters.