Mechanism and control of secondary diseases caused by improper seepage control in subway structures

Subway leaks are a common disease that threatens operational safety, especially in areas where groundwater levels rise significantly. If leakage control does not fully consider changes in seepage paths, groundwater levels and water pressure, secondary diseases may easily occur. This paper takes the leakage control project of Beijing subway operating lines as a case to analyze three types of secondary diseases caused by improper management (only blocking downstream points without blocking water sources, not monitoring peripheral water level changes after treatment, and ignoring the pressure bearing capacity of existing weak points): changes in seepage paths lead to the emergence of new leakage points, rising groundwater level causes water inflow into shield doors, and increasing groundwater pressure breaks through pre-buried grouting pipes. Studies have shown that secondary diseases are rooted in the disturbance and imbalance of groundwater movement systems (path-water level-water pressure) caused by management behaviors. It is proposed that leakage control should follow a comprehensive prevention and control strategy of “source control first, path management supplemented, and water level and water pressure monitoring and dredging equally” to provide technical guidance for subway leakage control under similar complex hydrogeological conditions.