Stability of Spread Footing Above Void in Clay

Abstract

The stability of spread footing situated above a continuous void was investigated. The study involved a theoretical analysis and a model footing testing. The theoretical analysis was made using the finite element method in which the foundation soil was idealized as an elastic perfectly plastic material. The model footing testing was performed on a commercially available kaolinite, which was compacted to 95% compaction based on the standard Proctor compactive effort. The model footing test results were compared with those obtained from the finite element analysis. As a result of this study, a three‐dimensional finite element computer program was developed. Using this computer program, the stability of spread footing was analyzed for different conditions. The results of the analysis indicate that there is a critical region under the footing. Only when the void is located within this region will the footing performance be significantly affected by the presence of the void. The size of the critical region depends on several factors such as footing shape, soil property, void size and void shape. When the void is lócated within the critical region, the bearing capacity of the footing varies considerably with the void location.