Construction of subway station using the small pipe roof-beam method: A case study of Shifu Road station in Shenyang

Abstract

A case study of the Shifu Road station of Shenyang Metro Line 4 in China, which was constructed using the small pipe roof–beam method, is presented herein. The minimum buried depth of the Shifu Road station is only 4.2 m, and numerous urban and high-rise buildings are constructed above the station. The location, surroundings, geological conditions, design, and construction process of the Shifu Road Station is described herein. The settlement of the pipe roofs, beams, intermediate columns, and side piles; the vault settlement and horizontal convergence of the pilot tunnels; and the surface settlement are monitored. Subsequently, the station is compared with similar metro stations in terms of surface settlement and construction period. The results indicate that the excavation of the transverse pilot tunnel and the negative layer significantly affect the pipe-roof settlement above the intermediate column and the surface settlement of the station center, which constitutes more than 75 % of the total settlement. The surface settlement above the Z3 pilot tunnel is affected significantly by the excavation of the longitudinal pilot tunnel and constitutes approximately 80 % of the total settlement. The vault settlement and horizontal convergence of the pilot tunnels as well as the settlement of the beams, intermediate columns, and side piles exhibit staged changes throughout the construction period. Compared with the surface settlement of similar metro stations, that of the station investigated is approximately 63 % owing to the adoption of the small pipe roof–beam method, thus reducing the construction period by six months at the least. The results obtained show that the proposed method is advantageous for constructing shallow buried large-span metro stations and that it can serve as a reference for various applications.