Road performance investigation of slurry shield tunnel residue improved by industrial waste residues

This study is carried out to investigate the resource utilization of mud water shield residue. Industrial waste residues such as alkali slag and desulfurization gypsum are reasonably used to be combined with the traditional lime, in order to convert waste mud into qualified roadbed filling materials. Through the laboratory compaction tests, CBR tests, unconfined compressive strength tests, wetting-drying cycle tests and microscopic tests, the mechanical properties, immersion stability and durability of shield tunnel residue improved by lime-alkali slag and lime-desulfurization gypsum were studied, and the improvement mechanism was analyzed. The test results show that the mechanical properties of the soil were improved significantly after compound improvement. The water stability and durability were also greatly improved, with better mechanical properties for road use. Among them, the overall water stability performance and durability of the lime-desulfurization gypsum groups were better than the lime-alkali slag groups. During the wetting-drying cycles, the durability of the specimens mixed with 3% desulfurization gypsum was better, with only small cracks not penetrating the specimens during the cycles. The study shows that the shield tunnel residue has good mechanical properties after compound improvement of lime and desulfurization gypsum, and can be used as roadbed filling materials.