Parametric study of under-reamed piled ring foundation in soft clay

A numerical analysis of the under-reamed piled ring foundation was performed to comprehend the effect of randomly distributed fibre-reinforced sand (RDFS cushion) overlying the soft clay and the influence of providing the under-reams on the pile stem. The study has been carried out with respect to load sharing ratio, differential settlement, load improvement factor (Q_IF) and settlement reduction ratio (S_RR). Analysis of the results indicated that for the piled ring foundation, Q_IF and load sharing ratio increases, and differential settlement decreases with an increase in the number of under-reams on the pile stem and a decrease in the spacing between piles. Whereas, RDFS cushion underneath the ring foundation in the under-reamed piled ring foundation further increases Q_IF and decreases differential settlement and changes the behaviour of the under-reamed piled ring foundation towards the circular piled ring foundation. The differential settlement was reduced more for the pile arrangement patterns that had some piles near the ring foundation’s inner edge than that of the pile arrangement patterns with piles along the centerline of the ring foundation.