Study on the mechanical properties of geogrid-reinforced tunnel slag and particle breakage

The use of tunnel slag as roadbed filling can save resources and promote the sustainable and low-carbon development of transportation infrastructure.. To investigate the mechanical properties evolution law of tunnel slag as subgrade filler, SEM and large-scale triaxial tests were conducted to analyze its macroscopic, microscopic characteristics and particle breakage behavior. The study focuses on the impact of geogrid on the shear strength, deformation, and particle breakage of tunnel slag and its working mechanism. The results indicate that an increase in soft rock content reduces the shear strength and weakens its dilatancy. The average peak shear strength of grid reinforced dense specimens can be increased by 10%, and the residual shear strength can be increased by about 30%. The relative breakage index increases in an S-shaped pattern with increase in soft rock content. Higher confining pressure and soft rock content leads to more particle breakage, however, particle breakage in the reinforced specimens can be significantly reduced. The research findings contribute to the enhanced design and implementation of waste material repurposing, thereby advancing the sustainable development of infrastructure.