Groundwater drawdown induced ground settlement during tunneling - sensitivity analysis on influencing factors

This paper concerns a sensitivity analysis on influencing factors which affect tunnelling induced ground surface settlements in groundwater drawdown environment. A Seoul metro extension design project, in which ground settlements associated tunnelling-induced groundwater drawdown was a key design issue, was selected to identify governing mechanisms and influencing factors. A series of two-dimensional finite element analysis were performed on a number of conditions encountered in the project to form a database with due consideration of the tunnelling and groundwater interaction. The results of the parametric study were then analyzed so as to relate the influencing factors to the ground surface settlement development. Practical implications and findings of the study are discussed.