Design and Construction Work of the Upstream Temporary Coffering Facility for the Sameura Dam Upgrading Project

Abstract

The upstream temporary coffering facility for the Sameura Dam upgrading project employs a hybrid configuration integrating floating-type and conventional-type structures. Additionally, a novel buoyancy mitigation and gate-stop system was engineered and patented to counteract and support the buoyant forces generated on the gate body when it was drained. Japan's first helium gas recycling apparatus for saturation diving was implemented for construction operations, achieving significant cost reductions.