Soil failure patterns and load-sinkage relationships under interacting shallow footing and wheel arrangements

This study explores possible methods, based upon generating interactions between footing/wheel arrangements, for supporting a greater proportion of surface applied loads in the soil surface layers, rather than at depth. Such a change would reduce the risk of deep soil compaction occurring under high machinery loadings. In this work, shallow footings were used to simulate wheel arrangements. Dual and triple footing combinations were examined at different spacings and in different relative positions. This was to determine the effect of interactions within the soil failure zones beneath the footings, on the nature of soil deformation, interaction behaviour and the load-sinkage relationships. The mode of interaction was very dependent upon the spacing between the footings. Three interaction modes were identified and the load-sinkage relationships indicated that, with interaction, higher loads could be supported in the surface layers at given sinkages. A mathematical model, based upon Meyerhof's bearing capacity theory for shallow footings, was developed to predict the likely interaction modes and the additional forces that could be generated as a result of the footing interactions at different spacings. The model showed an acceptable level of agreement with the experimental data for a range of multiple footing sizes and spacings. (C) 2004 Silsoe Research Institute. All rights reserved Published by Elsevier Ltd.