METHOD FOR REINFORCING EXISTING CAISSON FOUNDATION

To provide a method for reinforcing an existing caisson foundation that can reinforce a caisson foundation without securing a dry working space and by reducing water pressure acting on and using a simple temporary structure.SOLUTION: A method for reinforcing an existing caisson foundation F1 by a steel plate comprises a step of excavating in a cofferdam 3 that installs a cofferdam (cofferdam body 3) and excavates sediment at the upper part of the caisson foundation F1 in the cofferdam 3, and a step of press-fitting a reinforcing steel plate that press-fits a reinforcing steel plate for reinforcing the caisson foundation F1, to the foundation around the existing caisson foundation F1. In the step of excavating in a cofferdam, sediment in the cofferdam 3 is excavated and removed without discharging water in the cofferdam 3 to the water bottom and while leaving water as it is.SELECTED DRAWING: Figure 2 【課題】ドライな作業空間を確保せず作用する水圧を低減することで簡易な仮設構造物を用いてケーソン基礎を補強可能な既設ケーソン基礎の補強方法を提供する。【解決手段】既設のケーソン基礎Ｆ１を鋼板で補強する方法において、仮締切（仮締切体３）を設置して仮締切３内のケーソン基礎Ｆ１の上方の土砂を掘削する仮締切３内掘削工程と、ケーソン基礎Ｆ１を補強する補強鋼板を既設ケーソン基礎Ｆ１の周囲の地盤に圧入する補強鋼板圧入工程と、を備え、前記仮締切内掘削工程では、仮締切３内の土砂を、仮締切３内の水を水底まで抜かずに存置したまま掘削して排土する。【選択図】図２