PREDICTION OF SURFACE SETTLEMENT DUE TO TWIN TUNNEL CONSTRUCTION IN SOFT GROUND OF HANOI METRO LINE 03

Abstract

Construction of tunnels in the soft ground causes ground surface settlement in the urban conditions, especially for tunnels near the surface. The prediction of ground surface settlement caused by a single tunnel is well established in many documents. However, the ground surface settlement induced by the construction of twin tunnels is not well understood, and methods of predicting ground surface settlement in such projects are currently limited. This paper presents the three-dimensional numerical results using the finite element software (Abaqus) for the prediction of surface settlements caused by twin horizontal tunnels of the Hanoi Metro Line 03 excavated in soft ground. One of the aims of the study is to estimate the effect of the distance between tunnels on the magnitude and shape of the surface settlement trough. The results show that the center-to-center spacing of the tunnels has a significant influence on both the magnitude and the shape of the transverse surface settlement trough. The maximum surface settlement developed over twin tunnels will be reduced with an increase in the tunnels’ center-to-center spacing.