Shaft Resistance of Shaft-grouted Bored Piles and Barrettes Recently Constructed in Ho Chi Minh City

Abstract

Recent years, several high-rise buildings have been constructed in Ho Chi Minh city, the largest and most dynamic city in Vietnam. The city is located in the Saigon-Dongnai River delta, where, especially in the central districts, bored piles and barrettes for the high-rise buildings need to be large and socketed in alluvial deposits at large depths. Shaft-grouting technique has been recently applied to increase shaft resistance of the bored piles and barrettes. This paper briefly presents latest shaft grouting technique applied to bored piles and barrettes in the city. A database of head down and bidirectional tests on well-instrumented grouted and not-grouted bored piles and barrettes was analysed to evaluate the enhancement of shaft resistance. Correlations between the ultimate unit shaft resistance (r_u) with the SPT N₆₀ value indicated that the r_u-value of grouted piles in both clayey and sandy soils was on average two times larger than that of not grouted piles. Estimated r_u-values obtained from β-method recommended in practice compared well with those obtained from the instrumented piles.