Abstract: Different geomorphologic zones of coral reef demonstrate different geological engineering behaviors and mechanical properties. In order to investigate the engineering behaviors and its regularity, a series of tests including plate loading test, deep spiral plate loading test, compaction test and resilience modulus test is conducted on different zones in Yongxing Island, South China Sea. Engineering mechanical parameters including bearing capacity, deformation modulus, rebound modulus of coral reef are obtained. The test results show that the bearing capacity and deformation modulus of artificial calcareous soil ground are higher than those of reef flat foundation and sand bar foundation. The bearing capacity of artificial calcareous soil ground ranges from 320 to 360 kPa, and its deformation modulus ranges from 95 to 200 MPa. The bearing capacity of ground satisfies the requirement of low-rise buildings. As settlement of calcareous ground accompanies instantaneously under loading, fast loading method can be adopted in the plate loading test. The bearing capacity of subgrade above underground water table increases with increasing depth, but decreases below underground water table. The modulus of resilience increases with compaction. It can reach a range from 472 to 730 MPa with the degree of compaction over 87%.

Key words: plate loading test, coral reef, ground bearing capacity, deformation modulus, modulus of resilience