Investigation on Axial Response of Pile Due to Staged Tunnelling: A Numerical Approach

Estimation of foundation and subsequently, superstructure response is essential to assess the preliminary risk due to tunnelling. Several aspects of pile, tunnel, and soil characteristics influence the pile response during staged tunnelling. The present study investigates the response of a single pile in cohesionless soil through three dimensional finite element analysis. The numerical modeling, tunnel geometry, and properties and the pile parameters investigated  are described here. Volume loss of tunnel, vertical load level on the pile, and lateral distance of pile from tunnel longitudinal axis on the axial response of pile have been investigated and reported here. Results of a large number of numerical analyses can identify and quantify the parameters influencing the pile response due to tunnelling. Volume loss of the tunnel significantly influences the axial response of the pile. Lateral and longitudinal influence zone of pile settlement due to tunnelling has been identified and reported here. Working load on the pile significantly reduces the initial design factor of safety due to tunnelling. The results of the present study are useful for preliminary assessment regarding the safety and stability of the existing pile foundations for a range of practical parameters of tunnel and pile.