Abstract: With the development of offshore oil, gas and fishery resources as well as the need of national defense, the scale of projects in coral reefs are becoming increasingly large. In the construction of island reefs, the retaining walls in the calcareous soil are often affected by external loads, and the laboratory model tests are performed to simulate the lateral earth pressures at different depths with respected to the external surcharge load. The variation of soil pressure on the retaining wall in the calcareous soils with the surcharge load is simulated under different work loading conditions. The results show that: when the surcharge is applied, the lateral earth pressure at each depth of the retaining wall increases with the increase of the surcharge. At a deeper depth, the increase rate of the lateral earth pressure becomes slower. When the surcharge loading distance is closer to the retaining wall, the surcharge load has a greater influence on the lateral earth pressure at shallower depths of the retaining wall than those of at the deeper depths. When the surcharge loading distance is further away from the model retaining wall, the surcharge load has a higher influence on the lateral earth pressure acting on the deeper depth of the retaining wall than those at the shallower depths. The form of the surcharge load includes the contact area and the contact shape of the loading, at the same loading footing area, the lateral earth pressure of a square plate is slightly larger than the lateral earth pressure induced by a circular plate. When a plate is loaded, the influence of load contact area relative to load contact shape on the lateral earth pressure on the retaining wall in calcareous soil has a larger impact.

Key words: Coral Reefs, Calcareous Soils, Surcharge Loads, Lateral Earth Pressures