Tunnelling effects on pile groups in sand

The construction of tunnels in urban areas often results in tunnelling very close to overlying piled foundations, potentially with serious consequences. A study was carried out at the University of Cambridge, UK to examine the effect of tunnelling-induced volume loss on piled foundations by means of centrifuge modelling. Tunnelling-induced changes in the load distribution on piles were investigated, as well as the settlements and rotations that pile groups underwent. Volume loss-induced changes in the load distribution on pile groups were found to be similar to those on single piles. Piles with their bases located within the zone of influence suffered a reduction in the mobilised base load, transferring load to the shaft during which very little settlement occurs. As in the case of single piles, the behaviour of pile groups could be predicted based on the zone of influence. The effect of tunnelling on piled foundations were shown to be less severe than commonly expected. For the covering abstract see ITRD E128041.