Abstract: The Nanhang Xincun Station of Guangzhou rail transit Line No. 12 is in Baiyun District, Guangzhou. The subsurface condition is mainly composed of saturated sandy layers and strongly weathered silty mudstone. There are fault zones, and the karst formations are well-developed, so there are strong requirements for the construction of the supporting structure. The support system of diaphragm wall plus internal support is adopted for the deep excavation project. By comparing the I-steel joint form of the west foundation pit diaphragm wall and the sleeve milling joint form of the east foundation pit diaphragm wall, it is found that the sleeve milling joint process is more suitable for the geology of the saturated sandy layers, and the sleeve milling joint process has the advantages of low construction difficulty, more cost effective and a good waterproof effect.

Key words: Sandy Layers, Diaphragm Wall, Sleeve Milling Joint, I-Steel Beam Joint, Comparative Analysis