Responses of high-rise building resting on piled raft to adjacent tunnel at different depths relative to piles

In this study, 3D coupled-consolidation numerical parametric study was conducted to predict the deformation mechanism of a 20 storey building sitting on (4x4) piled raft (with length of piles, Lp=30 m) to adjacent 6 m diameter (D) tunnelling in stiff clay. The influences of different tunnel locations relative to piles (i.e., zt/Lp) were investigated in this parametric study. In first case, the tunnel was excavated near the pile shafts with depth of tunnel axis (zt) of 9 m (i.e., zt/Lp). In second and third cases, tunnels were driven at zt of 30 m and 42 m (i.e., zt/Lp = 1.0 and 1.4), respectively. An advanced hypoplastic clay model (which is capable of taking small-strain stiffness in account) was adopted to capture soil behaviour. The computed results revealed that tunnelling activity adjacent to a building resting on piled raft caused significant settlement, differential settlement, lateral deflection, angular distortion in the building. In addition, substantial bending moment, shear forces and changes in axial load distribution along pile length were induced. The findings from the parametric study revealed that the building and pile responses significantly influenced by tunnel location relative to pile.