Study on the size effect of composite foundation under the load test

The size effect in the load test of composite foundation is studied through FEM analysis in the paper. From the result of study, we can see that the testing result on four piles area is closed to the result with the group piles effect in large-area composite foundation; In engineering, if the bearing capacity of the testing result from single or double pile composite foundation is used in large area composite foundation, the result is unsafe, so the bearing capacity must be reduced; the subsidence ratio of different cushion cap and the square root of area ratio of cushion cap are general shown in linear relation.