Excavation of a 69-m diameter and 94-m high cavern for the Hyper-Kamiokande detector

TL;DR

This paper details the engineering challenges, design choices, and construction methods involved in excavating one of the world's largest underground caverns for the Hyper-Kamiokande detector, emphasizing observational design strategies.

Contribution

It presents the first comprehensive account of the design and construction process for a massive underground cavern using an observational approach.

Findings

Successful excavation of a 69-m diameter, 94-m high cavern underground.

Implementation of an information-based design and construction approach.

Overcoming major engineering challenges related to size and geology.

Abstract

The excavation of the Hyper-Kamiokande cavern, 600 m underground, is complete. Measuring 69 m in diameter and 94 m in height, it is among the world's largest rock caverns. A vertically oriented, dome-capped cylindrical design was chosen to optimize cost and performance. Combined with substantial overburden, the geometry posed major engineering challenges. This paper outlines the underground works, main cavern design, excavation plan, and the evolution of support design and construction methods during excavation, namely the information-based (observational) design and construction approach.