Research and implementation of eco-grouting material derived from shield tunneling muck

Abstract

During shield tunneling construction, a significant amount of waste muck is generated, presenting challenges due to its high volume, complex composition, and difficult disposal. Effectively managing this muck has become a pressing issue in shield tunneling projects. This study uses the Nanjing Metro Line 5 shield tunneling project as a case study, employing shield tunneling muck to prepare eco-grouting materials. The research investigates the operational and mechanical properties of these grouting materials. Optimal slurry densities and mixing ratios for two types of shield tunneling muck were proposed, and the curing mechanism of grouting materials was analyzed. These eco-grouting materials are then applied in real engineering projects, and their efficacy is verified through surface subsidence monitoring. The findings reveal that a slurry density of 1.65 for Line 5 muck and 1.55 for Line 9 muck, mixed in a 2:1 ratio, result in composite slurries with superior comprehensive performance concerning apparent density, consistency, setting time, water permeability rate, stone formation rate, compressive strength, and water-land strength ratio. The increased content of C-S-H and AFt in these composite slurries effectively fills internal voids, thereby enhancing material performance. The maximum surface settlement during muck grouting construction is approximately 20 mm, significantly less than the approximately 25 mm observed with conventional grouting materials, underscoring the superior effectiveness of eco-grouting materials in shield tunneling.

Keywords

• Shield tunneling muck
• Synchronous grouting material
• Mechanical properties
• Microstructures