EXPERIENCE WITH ROADS AND BUILDINGS ON EXPANSIVE CLAYS

Abstract

The procedures used for designing safe and economic structures to resist load-induced deformation are inadequate for the design of roads and buildings on expansive clays. For these clays, increase in moisture causes not only a decrease in strength but also volume expansion that results in cracked buildings and rough pavements. A method of quantifying the amount of heave expected (depending on surcharge pressures), the depth of replacement with nonswelling materials, and the final equilibrium suction values are presented. The procedure is based on one-dimensional laboratory swelling curves. Since time, site, and budget limitations frequently do not allow for complete laboratory testing, commonly used empirical correlations are discussed. A method of calibrating these correlations, which are usually based on simple index tests is presented. The importance of post construction observations and comments on increased interest in the legal aspects of the problem are presented. A review of some early publications is included along with flow charts and a program written in BASIC for computing heave.