Behavior of Overdeformed Shield Tunnel Lining under Grouting Treatment: Field Experiment

Abstract

Shield tunnel structures are commonly found to be overdeformed in Eastern China soft ground due to adjacent engineering activities. Grouting treatment could serve as a viable solution to actively reduce the excessive diametrical expansion of tunnel linings. However, understanding the grouting-induced effects on adjacent tunnel structures remains preliminary due to the scarcity of well-documented case histories. In this study, a field experiment was conducted to explore a shield metro tunnel’s real performance during grouting treatments. An extensive monitoring scheme was deployed while varied geometrical grouting arrangements were carried out. The tests provided a comprehensive database of the tunnel responses in multiple temporal resolution levels, both during the entire course of the grouting treatment and within single grouting operations. Investigations are carried out over the influencing factors of the grouting efficiency. The experimental observations suggest that grouting efficiency tends to evolve with time and can be affected by various geometrical grouting parameters. Observations are also presented and discussed in detail for the influence of grouting history on the convergence distribution and the tunnel’s performance after the termination of all grouting operations. Time-variant behaviors of the tunnel are depicted in detail, such as the convergence recovery and rebound during the grouting process. Overall, this case study brings new insights into understanding the grouting-induced tunnel lining response. It can also serve as a benchmark for further theoretical and numerical studies.