Prefabricated structure for tunnel cloche - has tubular half frames fitted together and held by bolted longitudinal and end stays

摘要

The structure comprises curved vertical hoops (1), the ends of which are secured to rails on the surface of the ground. Each hoop is a tubular half-frame, held by a pin and socket joint at the top. They are maintained upright by longitudinal spars (2) fastened to the hoops by bolted U-clips. At specified intervals, cross braces (30,31) are introduced. These are flat strips bolted onto lugs on the sides of the hoops. Each end of the cloche has an access opening (40,46) and further support is provided by intermediate longitudinal and end stays (3,5).