Lateral Pressures on Retaining Walls Due to Backfill Surface Loads HR-14, 1955

(1955) Lateral Pressures on Retaining Walls Due to Backfill Surface Loads HR-14, 1955. Transportation, Department of

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Abstract

For many decades the traditional method of evaluating the lateral pressure on a retaining wall due to a load applied at the surface of the soil backfill has been to substitute a uniformly distributed load for the actual load, and then calculate the pressure by either the Rankine or the Coulomb classical theory. This method of approach to the problem has several shortcomings and disadvantages. First, there is no logical or scientific basis for determining the magnitude of the uniformly distributed load in relation to the actual load. Judgement and intuition are the only guides for this substitution. Second, the lateral pressure on the wall resulting from the substitution is of uniform intensity throughout the entire height of the structure, whereas the intensity of pressure due to the actual load may vary considerably throughout the height of the wall. The Iowa Engineering Experiment Station conducted experimental research during the decade from 1931 to 1941 to determine the lateral pressure on a wall due to concentrated loads applied at the backfill surface and to uniformly distributed line or strip loads parallel to the wall. These studies indicated that the surface loads produced lateral pressures which were closely related to the pressures calculated by the Boussinesq theory of stress distribution in a semi-infinite elastic medium and provided a basis for further study of the influence of loads applied at the backfill surface. More recently, under the sponsorship of the Iowa Highway Research Board and the Iowa Highway Commission, further studies have been conducted in which lateral pressures due to uniformly distributed loads over finite areas on the soil backfill have been measured. This paper contains a resume of the earlier research and a detailed presentation of data obtained in the recent studies, together with a correlation with the Boussinesq theory.