Abstract: The project is located in the business centre of the city. The soil of foundation pit is strongly permeable sand layer and connected with the seawater. The field land is narrow, and the surroundings are nervous. The ultra-deep excavation requires to control the deformation and effective waterproof in coastal deep sand foundation. The additional load near the pile foundation constructed in the city center is calculated using the method of stratified frictional resistance. The frictional resistance of the pile is translated into the layered additional load. The supporting structure using pile anchor type and anchor pipe is used successfully in alluvial sand excavations. The construction process is simple and the quality is reliable, and the disturbance is small.