Loop line CF640 section shield tunnel with connecting passage – ground improvement works to improve the outer periphery of scheduled openings and tunnel junctions, and to overcome proximity of shield drilling and shallow soil cover. Also, to overcome site strength and water-resistance for passage excavation.The scope of the project was cross-line work, well shield departure section, shallow soil covering section and ground improvement grouting of the connecting passage.In this work, CB grout and sodium silicate was injected using the Double Packer method to improve the strength and watertightness.