The load on a buried structure's flat roof, under static conditions, i
s influenced by a soil-structure interaction phenomenon, known as arch
ing. The possibility of controlling this mechanism by application of a
soft layer in the soil above the roof is investigated and described h
erein. New definitions, that better describe various aspects of the ph
enomenon, are proposed, and used in a quantitative analysis of the pro
blem. The effects of the soft layer are discussed and it is shown that
there is an optimal length of the soft layer that yields minimal load
ing on the buried roof.