Safety Risks and Protection Measures for City Wall during Construction and Operation of Xi’an Metro

Abstract

The Xi’an City Wall (XCW) is a typical ancient building in Xi’an that is well known for its history and culture. The Xi’an Metro crosses below the XCW at various locations, which may pose hazards of cracking or collapsing the XCW due to the irregular settlement of the wall foundation during tunneling and vibrations induced by train operation. To minimize the effect of the metro on the XCW, the authors exhibit different mitigation measures in this paper, mainly including route optimization, active control technology during tunneling, foundation reinforcement, building reinforcement, and floating slab technology for damping train vibrations. Meanwhile, the case studies about the construction stage in Line 4 of the Xi’an Metro near the Heping Gate and the vibration effect during the metro operation stage were conducted. After employing the suitable countermeasures, the maximum foundation settlement and the maximum vibration velocity of the XCW could be controlled effectively within the guideline values.