CONTRIBUTION TO THE ANALYSIS OF RESTRAINT IN SOIL

The restraint of power-line pylons, highway posts, and similar cantilever structures fixed in prismatic block foundations presents an interesting problem of combined action of horizontal and vertical couples in soil. An improved method is proposed for the conventional analysis used for detailed description and calculation of contact pressures, forces and moments acting on the vertical faces of a prismatic foundation. The method is based on Winkler's stress-strain relationship in soil expressed by a subgrade modulus which varies exponentially with depth, due to the formula K z = K t ( z/t ) n . Results of three full scale tests on power-line pylons confirm the theoretical findings regarding the location of pivot at the sole depth and the magnitude of tilt of such foundations in clay.