The Arch in Soil Arching

Soil arching action or “bin effect” is usually quantified by use of a horizontal differential element whose support derives in part from Rankine theory. In the 1940's, Krynine mathematically proved this incorrect. The present analysis substitutes a catenary arch describing the path of the minor principal stress, which thus is complementary to a structural arch, and dips downward instead of upward if supportive. Soil arching action develops in two stages: The first involves rotation of the principal stresses adjacent to a rough wall and causes horizontal wall pressures to significantly exceed those from classical theory simulating a Ko pressure distribution even in loose backfill soil. The second stage reduces pressures on the lower wall to give a curvilinear distribution typically centered at a height 0.42 times the height of the wall and in close agreement with published data.