Method of construction of a vault, bearing piece and half-shell for construction of the vault

摘要

The tunnel is made from a series of prefabricated halfshells (1, 2) with their lower ends set in sole plate channels and their upper ends recessed to receive a key of a cast concrete material. Before the key is cast the upper ends of the half-shells are fitted with temporary thrust assemblies (30, 50) which leave a gap in the base (14) of the recess between the half-shells' projecting edges (22). Once the key has been cast and has set the thrust assemblies are removed and the load transferred to the key.