Shaft excavation at the ground bottom of a lake etc uses a tower of stacked ring concrete components forming a watertight interior to be pumped out for access to the ground bottom

摘要

For the excavation of a shaft, at the ground bottom of a lake and the like, a concrete ring shaft component is prepared with a hollow section (22) through it, and a foundation base (16) is prepared on the ground bottom level (12) of the water. The shaft components are stacked on the foundation (16) to form a watertight tower (18) to project over the water level (14). Water is pumped out of the hollow interior (23) of the tower, and the structure of the tower blocks resists external water pressure and any current flows. The ground bottom material is excavated from the hollow interior (23) at the foundation level (16) for access to the bottom level (12).