Shells are usually used as structural elements in buildings. In Germany they showed remarkable resistance to the effects of bombing during World War II. About 1 decade later, the possibility of employing shells in foundation engineering was explored. Surveys of the literature indicate that shell foundations have been employed effectively in different parts of the world and were proven to provide an overall economical alternative to the conventional flat foundations. However, the geotechnical design of these footings remained the same as for their respective flat ones. Accordingly, the advantages of shell geometry in foundation engineering has not yet been explored in the design of these footings. The objective of the present study is to examine the overall geotechnical behavior of three types of shell foundations resting on sand under axial loading conditions, namely, triangular, conical, and pyramidal shells. Furthermore, the resulting bearing capacities and settlements will be compared with conventional strip, circular, and square flat foundations. The present paper presents an experimental study on nine foundation models tested on loose, medium, and dense sand states. The influence of shell configuration and embedment depth on the ultimate bearing capacity and settlement will be presented. The results of the present experimental investigation have shown the admirable performance of shell foundations with respect to ultimate bearing capacity and settlement characteristics. Shell foundations provide higher resistance to lateral loading as compared with flat ones, and thus they will perform better in earthquake regions.Key words: shell foundation, experimental investigation, bearing capacity, settlement, sand, geotechnical engineering.
Study on the ultimate bearing capacity of a strip footing influenced by an irregular underlying cavity in karst areas