To further refine the classification criteria for muddy-silty coasts,we conduct the sedimentation-consolidation experiments on sediments with clay contents ranging from 10% to 30% on the basis of the projects of the 300,000-ton channel of Lianyungang Port.By integrating historical data with field observations,we systematically refine the methodological principle and methodologies for determining critical thresholds of three critical parameters in coastal classification criteria including specifically median grain size,clay content,and plasticity index,and optimize and improve the classification criteria for silt-sandy coasts.The results show that the coasts with median diameter less than or equal to 0.03 mm,clay content greater than or equal to 25%,and plasticity index greater than 17 are defined as the muddy coasts.The coasts with median diameter between 0.03 mm(not included) and 0.06 mm,clay content between 15% and 25%(not included),and plasticity index between 10(not included) and 17 are defined as transitional between muddy and silty coasts.The coasts with median diameter between 0.06 mm(not included) and 0.10 mm,clay content less than 15% and plasticity index less than or equal to 10 are defined as the silty coasts.The coasts with median diameter greater than 0.10 mm and clay content nearly 0% are defined as the sandy coast.