Coral sand is a type of soil with special engineering properties. It is of great significance to study the bearing capacity of coral sand for construction of islands and reefs in the South China Sea. The influence of density and gradation of coral sand

shape and size of load plate on the bearing capacity of coral sand foundation were quantitatively studied by self-made indoor model device of plate load

and bearing capacities of coral sand and quartz sand were compared. Test results show that

compared with quartz sand with the same density

coral sand has prominent flat features and sharp edges and corners

which leads to an increase of internal friction angle and further leads to an increase of its bearing capacity. Settlement under the same load is much smaller than that of the former

and size effect of foundation on bearing capacity is obviously greater than that of quartz sand. However

dependence coefficient of stress level of coral sand foundation soil is linearly related to its relative density

and internal friction angle is significantly affected by gradation. Relationship between bearing capacity coefficient of foundation Nγ and internal friction angle ? is established. At the same time

the bearing capacity of coral sand foundation increases with the increase of load plate size

and the bearing capacity of coral sand foundation under square foundation is obviously higher than that of circular foundation with the same area

and size effect is more obvious

which shows that the foundation type has practical significance on improving the bearing capacity in practical engineering. Based on the Meyerhof formula

a modified formula of foundation bearing capacity for coral sand is also proposed

which improves the accuracy of calculation results of bearing capacity of coral sand.