南京长江第四大桥北锚碇沉井基础施工监控技术

Construction Monitoring Techniques for North Anchorage Caisson Foundation of the Fourth Nanjing Changjiang River Bridge

南京长江第四大桥北锚碇采用沉井基础,尺寸为69.0 m×58.0 m×52.8 m,距长江大堤仅90 m。沉井体积庞大,所处区域地质条件复杂,覆盖层较厚。依据规范并结合以往的施工经验,提出沉井几何姿态监控标准。介绍沉井下沉深度和平面位置及偏斜、刃脚踏面反力、沉井侧壁土压力、沉井结构应力、地下水位与井内水位、沉井底部土体开挖地形、地表沉降和长江防洪大堤沉降量的监测方案。通过施工监测,掌握沉井下沉的实时信息,为施工提供指导信息,确保施工安全顺利进行。

The caisson in dimensions of 69.0 m×58.0 m×52.8 m is used for the foundation of the north anchorage of the Fourth Nanjing Changjiang River Bridge and is set at a place only 90 m apart from the river dyke. The caisson is huge, the place where it is located is geologically complicated and the overburden stratum is deep. In accordance with the technical specification and with reference to the previous construction experiences, the criteria for monitoring the status of the caisson during sinking are formulated. The specific monitoring of the sinking depth, plane positions, offsetting, cutting edge reaction force, side wall soil resistance, structural stress of the caisson, the underground water level, the water level inside the caisson, the excavated ground topography at the bottom of the caisson, the ground surface settlement and the settlement the river dyke are all presented herewith. Through the monitoring, the real-time information of the caisson sinking has been understood, the guidance to the construction has been provided and the safe and smooth proceeding of the construction of the caisson has been ensured.