Experimental research on geotechnical engineering characteristics of coral reef in Xisha Islands

Coral reefs are widely distributed in Xisha Islands, which have special engineering properties. Coral reef geology from top to bottom is coral sand, coral gravel, coral reefs calcareous rock. Coral sand and coral gravel have the characteristics of mixed size particles, alternating accumulation of sand and gravel, great change of density and gradually coarsening from top to bottom. Coral reefs calcareous rocks are composed of loose bioclasts cemented, some of them are dense, and some of them are semi-cemented and weakly cemented. The geological age of the Xisha Islands within 50m was determined by carbon-14 radioisotope isotopic test. The bearing capacity and deformation characteristics of coral sand and coral gravel were analyzed by plate loading test, heavy dynamic penetration test, extra-heavy dynamic penetration test and standard penetration test. The physical and mechanical characteristics of coral reefs calcareous rock were studied by longitudinal wave velocity test, density test, porosity test and uniaxial compressive strength test.