Laboratory study of static and dynamic compaction grouting in triaxial condition

Abstract

This research paper is focused on the fundamental behaviour of applying static and dynamic compaction grouting techniques on completely decomposed granite (CDG) soils in Hong Kong. Using the modified triaxial apparatus and a novel pulse wave generator, laboratory tests were performed to identify the critical controllable factors of static and dynamic compaction grouting techniques in optimizing compaction effectiveness. The distinguishing feature of this laboratory apparatus is that it can simulate triaxial condition of static and dynamic compaction grouting. The effective confining pressure, the lateral pressure coefficient, excess pore water pressure, back pressure and void ratio change of the specimen were measured in this study. At the same time, the dynamic compaction grouting pressure, dynamic compaction frequency, and dynamic compaction duration were controlled. Moreover, the effects of effective confining pressure and injection rate on the compaction efficiency in static tests were studied. The study focused on the effect of dynamic compaction frequency, dynamic compaction duration, lateral pressure coefficient and initial dry density on the compaction efficiency of Hong Kong CDG soils.