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The west artificial island of Shenzhen-Zhongshan Link is enclosed by installation of steel cylinders and arc steel plates to form the island structure quickly. The artificial island was formed with a method of deep well dewatering with surcharge preloading of sand -fill with large overloading ratio to improve the soft soil in the island. After the ground improvement was completed, open-cut cast-in-place tunnel construction was carried out on the island. The bottom of the steel cylinders in the sea area where the artificial island is located sits mostly on coarse sand, gravelly sand, gravel-like strongly weathered rock and fragmentary strongly-weathered rock, which are connected to the sea and have high permeability. In order to ensure the seepage stability and inrush stability in the foundation pit of the west artificial island and achieve the result of water stopping, three rows of high pressure jet grouting piles are installed to form a water-stopping curtain wall inside the steel cylinders and the auxiliary arc cells of steel plates to block the seepage path inside and outside the steel cylinder enclosure. In this paper, the technology of construction of high-pressure jet grouting pile water-stopping curtain walls in offshore deep and thick sand backfill is studied systematically. The optimal construction parameters are determined and the construction technology is optimized and adjusted via testing and verification of the technology. It can provide experience and reference for similar projects. [ABSTRACT FROM AUTHOR]

The west artificial island of Shenzhen-Zhongshan Link adopts the rapid island-formation process by inserting large diameter steel cylinders into the enclosed island body on the sea bed. At present, the cases of rapid island-formation by steel cylinder are relatively few, and the research on the tilt of steel cylinder during construction and the stability of the cylinder need to be further deepened. Taking the west artificial island of Shenzhen-Zhongshan Link as an example, in view of the construction conditions of steel cylinder vibration and sinking until the formation of land area of artificial island, this paper analyzed the causes of the tilt of the cylinder under the comprehensive action of loads inside and outside the island, the results are closely related to the geological conditions and the lateral pressure and water pressure caused by the foundation reinforcement inside and outside the cylinder during construction. The monitoring results after foundation treatment in the island and the riprap of the island wall structure are basically completed show that the cylinder displacement and tilt have converged, and the security has been controlled. It provides some experience reference for further research on the stability of steel cylinder enclosure structure during construction in similar projects. [ABSTRACT FROM AUTHOR]