FOUNDATION ON STRONG SAND UNDERLAIN BY WEAK CLAY WITH GEOGRID AT THE INTERFACE

A number of laboratory model test results for the ultimate bearing cap acity of a surface strip foundation supported by a strong sand layer o f limited thickness underlain by a weak clay with a layer of geogrid a t the sand-clay interface has been presented. The tests were conducted at one relative density of compaction of sand and one undrained shear strength of clay. Two types of geogrid were used. Based on the model test results presented, it appears that the optimum height of the stro ng sand layer should be about two-thirds that of the foundation width for obtaining the maximum benefit from the geogrid reinforcement.