Abstract: Ground settlement is an issue of common concern in shallowburied parallel tunnel construction， especially in urban metro section construction. This paper presents a parametric study to investigate the influence of some important factors on ground settlement using numerical experiment method. The results indicate that the bimodal soil settlement results from the large tunnel center space and deep tunnel buried depth. The smaller ground settlement is achieved when horizontal distance and vertical distance are both close to 25D in inclined alignment and the bigger tunnel space in vertical alignment with the 2D tunnel depth. Grouting is very effective to control arch crown settlement. Improving the gouting parameters is better than increasing the thickness of grouting layer to control the arch crown settlement.

Key words: parallel tunnels construction, numerical experiment, ground settlement, grouting, tunnel depth