Interpretation of plate load tests on residual soil site

This paper addresses problems of interpreting the results of loading tests in a residual homogeneous, cohesive-frictional soil. Data are presented comparing load-settlement behavior measured from tests carried out using circular steel plates ranging from 0.30 to 0.60 m diameter and square concrete footings ranging in size from 0.40 to 1.00 m. This paper stresses the need to express test results in terms of dimensionless variables in a plot of normalized applied pressure versus settlement-to-diameter ratio. In this space, the effect of the size of the loaded area on measured settlement and on bearing capacity is shown to be negligible for this residual soil site. This approach implies that a unique relationship between normalized pressure and settlement-to-diameter ratio is observed for both small and large vertical displacements. Interpretation of load tests is made within the context of elastic- and elastoplastic theories. For ultimate bearing capacity, reduced strength parameters are used to provide a realistic estimation of ultimate loads. Finally, a numerical approach is proposed for predicting the complete load-settlement behavior of shallow foundations on cemented soil deposits.