Analysis of Stratum Settlement Laws Caused by the Construction of Shallow-Buried Expressway Tunnels with Large Span and Small Spacing

Abstract

Many tunnels with large spans and small spacing have been constructed due to the rapid development and construction of China’s expressways. The stratum settlement caused by the construction of these tunnels in shallow sections is large and difficult to control, and ensuring stratum stability is a key issue in the construction of expressway tunnels. According to the research differences in the prediction of stratum settlement under the tunnel construction at present, based on stochastic medium theory, in this study, the prediction formula for stratum settlement in the construction of double-line tunnels was revised and optimized by monitoring the construction of expressway tunnels with large spans and small spacing in shallow sections. The accuracy of the revised formula was verified by comparing it with on-site monitoring data. A numerical calculation method was also used to select effective deformation control measures. Results showed that the revised prediction formula of stratum settlement could roughly predict the position and shape of the settlement tank and reflect the uneven settlement caused by the mutual influence of double-line excavation. The accuracy of stratum settlement prediction was high. Moreover, reasonable grouting could effectively reduce stratum settlement. A reasonable grouting plan should be selected during construction in accordance with the actual situation to avoid material wastage and increased costs caused by excess grouting.