Abstract: The width of cross section of seawall with deep silt foundation treated by drainage and solidification was investigated in-depth. By statistical regression analysis on the physical-mechanical parameters of silt in coastal areas of Zhejiang province, the empirical relationship between the natural shear strength and natural water content of silt was obtained. On the basis of sliding stability calculation, the relations among the width B and height H of the seawall, the natural shear strength index of silt-seam, and the thickness of silt-seam were analyzed. The formula of seawall's total  width B total was also gained. Verification showed that the result of the formula was consistent with the actual project. In addition, sensitive analysis was carried out to research the variation of sliding safety coefficient against the change of silt shear strength. It was found that the impact of internal friction angle on anti-sliding coefficient was larger than that of cohesive force.

Key words: sliding stability of seawall, shear strength of silt, natural water content of silt, critical depth of silt, bottom width of seawall