COMPREHENSIVE GROUTING FOR THE CROSS-PASSAGE REINFORCEMENT OF SUBWAY TUNNEL IN WATER-RICH ROUND GRAVEL STRATUM

Anti-seepage reinforcement measures such as underground continuous wall+sleeve valve tube grouting were adopted in one cross-passage of subway tunnel in Nanning, whose structure located in water-rich round gravel stratum, but they failed to achieve the expected treatment purpose. In view of the characteristics and difficulties of the cross-passage, such as large thickness, strong permeability, and poor self-stability of the gravel layer, the comprehensive grouting of cement-paste slurry combined with stable slurry reinforcement+AC-MS acrylate chemical grouting is proposed. The problem of anti-seepage reinforcement of the water-rich round gravel stratum was solved successfully. The excavation and monitoring results showed that the water-rich round gravel was well cemented. The cemented body was hard and dense. The stability and permeability was improved significantly after comprehensive grouting. No collapse, instability, and mud flow occurred during excavation. The anti-seepage reinforcement effect is remarkable which can take a reference for the similar engineering.