Abstract: The successful application of sealing curtain in an excavation in thick sand layer coastal region is introduced. The curtain combines triple-tube jet grouting piles with uniaxial cement mixing piles. The practices have proved that the combined curtain has solved the problem of poor interlocking and easy separation at the bottom due to the difficulty of vertical uniaxial cement mixing piles in thick sand layer. It has also solved the difficulty to form continuous jet grouting piles because the cement slurry is easily carried away by tides in coastal region. At the same time, the water-resisting layer is locally thinner in the southern area of the project, which will lead to piping in the design and calculation. Based on the hydrogeological conditions and the calculation, some relief wells and drainage wells are arranged so as to avoid the piping of seepage damage in the project.