Large Cavity Project
in the deepest underground
in the Power Plant Station at Kochi

This is a construction of a large cavity (length: 54 m × width: 18 m × maximum height: 33 m) at 200 m underground.
Due to the geological conditions of the strongly delaminated and anisotropic Sanbagawa metamorphic rock, PS anchors are installed upwardly from the ceiling to the wall to prevent rock collapse during cavity excavation and to ensure long-term stability. Because of the unprecedented upward anchors, distinctive construction methods are being employed, such as the making a tendon insertion machine and the use of expandable grouting materials.