Abstract：Under the attacking of a strong storm，during constructing the guiding dike in Yangtze Estuary，some of the caisson structures were sinking into the soil for 1–5 m or slide away about 20 m from the original place. Dynamic triaxial tests are carried out to simulate the behavior of foundation soils under wave loading. The results show that the excessive settlement and lateral movement of the caissons are due to the strength weakening of the soft clay during the strong storm，and also show that the ability of the soft clay to resist the wave force will be greatly increased when the soft soil samples are suitably improved. Based on the test results，an improvement method associating vertical drains with surcharge loading is proposed to strengthen the foundation soil. With the improved soil foundation，the dike was reconstructed and underwent several strong storms without any damage.
