Study On Engineering Geological Properties Of Coral Reefs And Feasibility Of Large Project Construction On Nansha Islands

Nansha Islands which locate on the southernmost South China Sea hold in storeabundant oil, natural gas and biology resources. It's inevitable to deal withengineering geology of coral reefs when safeguarding and developing Nansha Islands.Coral reef is a kind of peculiar geological body which has special engineeringcharacteristics. In order to empolder ocean resources and instruct engineeringconstruction, this thesis synthetically analyzed regional geology, terrain, depositsediments, hydrology, and sediments of coral reefs, have systemically studied themechanical characteristics of calcareous sand and coral reef through indoor tests.1. Many factors including regional engineering geology environment,hydrodynamic environment, terrain, physiognomy have been studied to evaluate theirinfluence to coral reef engineering. It's considered that atoll reefs and table reefs aresuitable for engineering construction and the reef flat on atolls is most perfect.2,Geomorphology of coral reefs was divided into 6 phase belts and theenvironment characteristics and engineering geology were thoroughly studied. Thechipping deposit of superficial layer of coral reefs was divided into four kind ofstructure type and the feasibility for engineering construction of each zone wasestimated.3,The relationship between wave properties and density , porosity about reeflimestone which is sampling from Zhubi Jiao in Nansha Islands are studied. Andstrength characteristics and failure pattern of reef limestone are analyzed throughBrazil splitting test, uniaxial compressive strength, triaxial compressive strength.4,8 indoor plate load test of calcareous sand have been done to study bearingcapacity and deformation characteristics of calcareous sand ground about differentrelative compaction, different load plates, dry and saturated sand as well as quartzsand. The difference about bearing capacity and deformation characteristics betweencalcareous sand and quartz sand is analyzed.5,It's considered that the reef flat of atoll reefs is suitable to build man-madeisland, aerodrome runway and other structures after studying the engineeringenvironment of reef flat , mechanical property of reef limestone and calcareous sandwhich are also good architectural materials.6,The feasibility of constructing runway of using calcareous sand was studied.The settlement of calcareous sand will be reduced to less than 150mm if deformationmodulus exceeds 25MPa after rolling. Otherwise, the calcareous sand ground shouldbe reinforced.At last, the achievements of the research in this paper were concluded, and thedirection of this thesis was also presented based on the shortcoming of the author'sresearch.