Probably one of the most successful auger methods is the use of the hollow tube auger in soft silt, etc., where
water and squeezing of soft silts in the surrounding ground can cause necking problems for many other systems, i.e. squeezing in of the pile shaft due to side pressure. The use of the hollow auger and injected sand cement grout can produce good-quality piles in these soft and difﬁcult conditions at competitive prices, particularly where large numbers of piles are involved. For small numbers of piles the on-site cost of the rig and grouting plant can prove to be prohibitively expensive.
Fig. 9.37 Under-reamed augered pile.