LAUSR

The distribution of the contact stress between a spread foundation and subsoil has been regarded as a classic issue in geotechnical engineering. Previous studies on this problem mainly focused on rigid foundations under axial loads, usually with width-to-height ratios (w/h) of 2.5 or less. However, flexible foundations are much more widespread in engineering applications. To investigate the effect of rigidity on the contact stress distribution and settlement deformation under axial and eccentric compression, two series of model tests on spread foundations (with w/h ratios from 2.5 to 4.0) placed on silty sand and clay were conducted. The results indicate that, under axial load, the contact stress in the central area of the rigid foundation is smaller than that around the edges. However, as the aspect ratio increases, the opposite occurs. Furthermore, in the eccentric compression progress, the w/h ratio (representing the rigidity of a foundation) has an important impact on the pressure distribution. A clear asymmetric distribution of pressure was observed under the eccentric load, and the maximal stress appears around the edges of the eccentric side under the rigid foundations, while under the flexible foundations the maximal stress appears in the central area. These research results can provide a practical reference for engineering applications with flexible foundations.