沪通长江大桥主航道桥桥塔墩钢沉井定位施工技术

Positioning Construction Techniques for Pylon Pier Steel Caissons of Hutong Changjiang River Bridge

沪通长江大桥主航道桥为(140+462+1 092+462+140)m双塔连续钢桁梁斜拉桥,28号桥塔墩沉井顶平面尺寸为86.9m×58.7m,钢沉井高50m。为解决钢沉井快速定位、精确着床的难题,采用"锚桩+重力锚"相结合的锚桩锚碇系统进行钢沉井定位施工。锚桩锚碇系统由锚桩、蛙式重力锚、钢丝绳、液压连续千斤顶及张拉控制系统组成,锚桩采用长53m钢管桩,锚固点位于河床面;收缆系统由大直径钢丝绳+钢绞线组成,设置在沉井顶面;主锚绳采用3.5 m的钢桩下端套入110mm的钢丝绳套进行锚固,并设置限位框架防止上滑;采用ANSYS有限元软件建立锚桩锚碇系统模型,得到结构受力及安全满足要求。施工时,采用2台联动APE400振动锤插打锚桩,锚碇抛锚定位后,采用锚桩锚碇系统进行钢沉井过缆、定位及着床施工。实践表明,沉井平面位置和姿态满足设计要求。

The main navigational channel bridge of Hutong Changjiang River Bridge is a twopylon continuous steel truss girder cable-stayed bridge with span arrangement of（140＋462＋1 092＋462＋140）m.The steel caisson of the pylon pier No.28 is 50min depth,the top of which measures 86.9m×58.7min plan.To resolve the problems of rapid positioning and accurate landing of the steel caisson,the anchor piles and anchor block system formed of anchor piles and gravity anchor block was used to the positioning construction of the steel caisson.The system comprises the anchor piles,frog-like gravity anchor block,steel ropes,hydraulic continuous jacks and tensioning control system.The anchor piles are the steel pipe piles of 53 min length and the anchoring points are located on the surface of the riverbed.The cable retraction system is formed of large-diameter steel ropes and steel strands,installed on the top of the caisson.The main anchor rope was anchored by the3.5 msteel piles,the end of which were inserted into the110 mm steel rope sheaths,and the restriction frame was set to prevent sliding.The ANSYS finite element software was used to establish the models of the anchor piles and anchor block system.The results of the analysis show that the load bearing capacity and safety of the structure meet the requirements.During the construction,two APE400 vibratory pile-driving hammers in tandem were used to drive the anchor piles.Once the anchor block was moored,the anchor piles and anchor block system was used to the cable threading,positioning and landing construction of the steel caisson.The engineering practice proves that the plan location and the position of the caisson meet the design requirements.