Comparison of results of oedometer and plate load tests performed on collapsible soils

Abstract

Physical and mechanical properties of collapsible soils (soil deformation parameters such as deformation moduli, collapse potentials, allowable pressure values, etc.) can be determined by different laboratory and field testing methods. Empirical relationships between oedometer deformation moduli determined for collapsible loessial soils deposited in the vicinity of the city of Odessa (Ukraine) and soil void ratios and degrees of saturation are introduced and analyzed. Plate load tests are commonly recognized as the reliable source for the evaluation of allowable pressures under foundations. This information and soil deformation moduli can be obtained from plate load-settlement curves. The paper describes a plate load testing technique developed for collapsible soils. Analytical formulae for the estimation of bearing plate settlements under applied loads is offered for quasi-uniform soils. A new approach for the selection of allowable pressure values is proposed. Field deformation moduli are calculated using a suggested formula. Results of more than 140 plate load tests performed on Odessa collapsible loessial soils at depths of 1.8–9.5 m are analyzed. Field deformation moduli and allowable pressures for the studied group of soils depend on soil porosity and moisture conditions. Plate load and oedometer test deformation moduli are compared and correlation coefficients are calculated as functions of soil void ratios and degrees of saturation.