Chart for Allowable Soil Pressure Based on Schmertmann's Method

Abstract

Curves for estimating allowable pressures, for square footings on sand, have been computed using Schmertmann's method for settlement prediction. Although the form of these curves is consistent with Taylor's qualitative assessment, there are significant differences between the results obtained and those previusly published by other authors. To permit comparison with previous work, curves were computed using simplifying assumptions including uniform static cone resistance and a surface loading for square footings on soil depths greater than twice the footing width. The computed curves show that allowable values of soil pressure, for 25-mm settlement, vary substantially with width of footing (hence the previously published constant value approach may be oversimplified), and that for large footings, previously published values of soil pressure may be excessive.