Research on the interface characteristics of coal gangue with different geosynthetic reinforcements

Abstract

Coal gangue occupies substantial land resources. Using coal gangue as reinforcement fill material is an effective utilization method. The characteristics of the soil-reinforcement interface influence the safety and stability. Large-scale direct shear tests were conducted to study the interface characteristics of coal gangue with polypropylene woven geotextile, welded steel-plastic geogrid, and high-density polyethylene uniaxial geogrid. The tests revealed that the shear stress-shear displacement relationship is nonlinear and positively correlated with normal stress, with the breakage of burnt coal gangue particles observed during the process. The maximum shear stress and shear strength index of the interface for the three geosynthetics reinforced coal gangue are in the order of uniaxial high-density polyethylene (HDPE) geogrid showing the highest reinforcement strength, followed by the welded steel-plastic geogrid, with the polypropylene woven geotextile having the lowest strength. After HDPE geogrid reinforcement, interface friction angle slightly changes, but cohesion significantly increases, with an increase of 1156.9%. Considering the interface interactions, among the three geosynthetic materials, HDPE geogrid exhibits the most effective reinforcement effect on coal gangue, followed by the welded steel-plastic geogrid. The geotextile shows the least effectiveness in reinforcing burnt coal gangue. For reinforced coal gangue projects, HDPE geogrid is recommended as the reinforcing material.