Experimental and Numerical Behavior of Shallow Foundations on Sand Reinforced with Geogrid and Grid Anchor Under Cyclic Loading


Department of Civil Engineering,Shiraz University


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 e ects
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 di erent 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 di erent 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.