LAUSR

Abstract This paper presents a case of Gaojiayuan subway station of Beijing Subway Line 14 constructed using combined shield and shallow tunnelling method. The layout, geological and hydrogeological conditions, construction process and related measures to accelerate construction speed and safeguard ground stability of the station are illustrated. The ground surface settlements of the subway station due to construction were systematically monitored. The monitoring results showed that the surface settlements were mainly caused by shield tunnelling, side drifts excavation and double arch excavation. The surface settlement above the station crown of a cross section induced by the above-mentioned three construction stages accounted for about 3.45–7.28%, 35.65–45.54%, 51.01–57.40% of the total settlement value. Limit surface settlement was produced due to the installation of jet grouting columns and cast-in-place piles, and the settlement could be effectively controlled after the completion of pile-beam-arch-wall system. It is noted that grouting can effectively compensate the ground loss and heave the ground accordingly. Moreover, due to the inherent complexity of the subway station construction, the surface settlement curve in a section fluctuated and no longer followed the Gaussian distribution.