A Study of Seasonal River Water Level Fluctuations and Their Impact on the Upward Floating of Underlying Shield Tunnels

Abstract

Rivers exhibit significant water level fluctuations between dry and wet seasons, affecting nearby structures. These fluctuations cause the overlying shield tunnels to float upward, leading to defects such as misalignment and leakage in pipe segments. This study, based on the shield tunneling project for the Jinan Metro R3 line crossing the Daxin River, compared the deformation of pipe segments during dry and wet seasons using numerical simulations. During the wet season, floating and displacement of pipe segments increased, primarily at the junction between the riverbank and riverbed. This study discusses the influence of groundwater level, thickness of riverbed soil cover, geological parameters, and grouting layer quality on the uplift and displacement of the segments. Suggestions are made for advanced grouting reinforcement of the strata, improving the quality of synchronous grouting, and controlling the uplift using antipull piles and pressure plates, and their design parameters are discussed. The effectiveness of these control measures was verified using on-site research, providing a reference for seasonal river construction of shield tunnels in shallow soil.