Tunnel – pile interaction sequence: parametric studies

Abstract

As the population of the city is increasing, the scarce land available. Therefore, it is a need to consider an alternative way to support the development. Underground structures such as tunnel become a sustainable solution and widely used. However, tunnel construction leads to unpredictable circumstances, especially when advancing in the vicinity of pile foundations. Tunnel advancement leads to ground stress release. The ground stress redistribution gives additional loads in both horizontal and vertical directions to the nearby pile and risks jeopardizing the pile integrity. Many research focuses on tunnel affecting the pile in vicinity but a lack of study carried out for incoming pile affecting the existing tunnel. Therefore, this paper aimed to study tunnel–pile interaction by performing a parametric study of different construction sequences between the tunnel and pile by using numerical modelling. Parametric studies for pile-tunnel sequence and tunnel-pile sequence were carried out. The simulated model was first validated with previous studies prior to the parametric study. From the parametric results, it was found that the existing pile behaviour could be affected by a new tunnel construction in terms of horizontal stress, deflection and settlement. In opposite, a tunnel was not significantly affected by the new pile construction. This was confirmed by results from the induced stresses and bending moment in tunnel lining. The bending moment gives mirroring affect behaviour at the left and right sides of the tunnel indicating lining is stable although new piles are constructed in the tunnel vicinity with higher working loads.