杭州市下沙海塘始建于70年代，堤身结构型式为斜坡式海塘。近年来，因钱塘江江道水文条件变化，河床刷深，低水位降低，涌潮加大，底脚挂空，海塘多处遭损坏，成为险塘。通过下沙5号桥下游1km标准塘（试验段）小沉井群的实践，证明该方案解决了斜坡式海塘底脚防冲的难题，具有显著的经济效益和较好的推广价值。 Hangzhou Xiasha seawall was built in the 70s, the dike structure is a sloping seawall. In recent years, Qiantang River due to changes in hydrological conditions, the riverbed brush deep, low water level decreases, tide increases, the bottom of the Hanging, many damaged seawall, a dangerous pond. Through the practice of 1km standard caisson (experimental section) of the lower reaches of Xiasha Bridge No. 5, this project proves that this scheme has solved the problem of anti-punching at the foot of slope-type ponds, and has obvious economic benefits and good promotion value.