(1. Key Laboratory of Earthquake Engineering and Engineering Vibration，Institute of Engineering Mechanics，China Earthquake Administration，Harbin，Heilongjiang 150080，China；2. School of Civil Engineering，Tianjin University，Tianjin 300072，China；3. Institute of Coast Defense Engineering Design，Academy of Navy Research，PLA，Beijing 102202，China)
Abstract：The paper presents a fundamental understanding of the liquefaction characteristics in the engineering sites of coralline soils and points out the key issues in the further research on liquefaction of coralline soils. The post-earthquake investigation of liquefaction damages in the engineering sites of coralline soils and comparison of knowledge obtained from the research on the liquefaction events of the terrestrial soils are conducted. The analysis indicates that the liquefaction destruction phenomenon of the coralline soils will be same as those of the terrestrial sites of sandy and gravelly soils when subjected to strong earthquakes，and it will even become the main cause of the seismic damage of the artificial islands and reefs. The PGA of 0.1 g is the minimum seismic intensity that triggers the liquefaction of coralline soils and the liquefaction may occurs in coralline fill layers or lagoon sediments. The coralline soils in the actual engineering sites are composed of a wide graded cohesiveless soils from gravel to silt instead of pure calcareous sand. It is discovered that the grain size distribution of liquefied coralline soils are similar to those of the liquefied continental gravelly soils. The layers of coralline soils with high shear velocity can liquefy and triggering the liquefaction of coralline soils with good permeability requires special burial conditions. As a result，the method for evaluation of the terrestrial sand liquefaction is not applicable to coralline soils. There is objective risk of strong earthquake in the area of South China Sea and the grain size distribution of the reclaimed coralline soils in the artificial islands. Moreover，reefs in the area is comparable to the liquefied coralline soils and gravelly soils in the historical earthquakes. The key issues to evaluate liquefaction risk of coralline soils are the reappearance of the liquefaction process of coralline soils in the laboratory，the technique of defining the density of the coralline soils in the field and the liquefaction discriminant technology for engineering sites of coralline soils.
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2019, Vol. 38 
