EXPERIMENTAL AND NUMERICAL BEHAVIOR OF SHALLOW FOUNDATIONS ON SAND REINFORCED WITH GEOGRID AND GRID ANCHOR UNDER CYCLIC LOADING

There are many cases where the foundations of structures are subjected to cyclic loading in addition to static loading. Oil reservoir foundations with frequent discharges and lling or road embankments under repeatable trac loads are examples of such foundations. Although the amplitudes of the cyclic load is usually less than the permissible static load, the concern still exists for the amount of uniform and non uniform settlement of such structures. The soil under such foundations may be reinforced with geosynthetics to improve their engineering properties. This paper deals with the eects of using the new generation of reinforcements, grid-anchor, for the purpose of reducing the permanent settlement of these foundations under the in uence of dierent proportions of the ultimate load. Other items, such as the type and number of reinforcements, as well as the number of loading cycles, are studied experimentally. In all cases, the foundation is rst under the in uence of a xed static load equal to the weight of the structure itself and, then, the cyclic load in dierent proportions of the ultimate load is applied to it. The results show that by using grid-anchor and increasing the number of their layers in the same proportion as that of the cyclic load applied, the amounts of permanent settlements are reduced and the numbers of loading cycles to reach it are decreased. For comparison with the experimental ndings, similar to the conditions of the tests conducted, numerical models were made using a 3-D nite element software. The numerical results showed good agreement with the test results.