Applications of Big-Diameter Jet Grouting (BDJ) Method in Japan and Vietnam

This paper first introduces the principles of big-diameter jet grouting (BDJ) method and its application to some typical ground improvement projects in Japan and Vietnam with an emphasis on the advantages of the method at Metro Line 3 Hanoi and Vinh Tan Port in Vietnam. For the Metro Line 3 project, the method was an optimal solution, both technically and economically, to construct the bottom plugs of 3.0 m thick in deep and dense gravelly sand layer at Station S12. For the Vinh Tan port project, besides the quality assured, the portable system and high construction speed were the winning points of the method to improve a very deep soft clay layer along the river bank. The paper then presents a preliminary correlation between the equivalent elastic modulus (Es) and unconfined compressive strength (qu) of BDJ-cored samples in clayey soils obtained from some construction sites in Japan and Vietnam. The correlations can be a reference for geotechnical engineers in the preliminary designs of bearing capacity and settlement of the improved grounds.