PIT COVER, CONSTRUCTION STRUCTURE OF PIT COVER, MANUFACTURING METHOD, CONSTRUCTION METHOD, AND METHOD FOR ADJUSTING BUOYANCY

摘要

A pit cover 1 comprises a substantially rectangular tabular top plate 3, ribs provided on a reverse surface side of the top plate 3, handholds 5 provided on both edges in a width direction, and the like. On a reverse surface 1b side of the pit cover 1, a plurality of width direction ribs 7a is formed in the width direction of the pit cover 1, and a plurality of length direction ribs 7b substantially orthogonal to the width direction ribs 7a is formed in the length direction of the pit cover 1. Assuming locations surrounded by the width direction ribs 7a and the length direction ribs 7b to be spaces, the spaces disposed on both edges in the width direction of the pit cover 1 are the spaces 11a that open to an outer side in the width direction of the pit cover 1. Specifically, the spaces 11a are formed so as to be open only to a bottom surface side and one side surface side of the pit cover 1.