Interfacial shear behavior of gabion reinforced coal gangue and stability of embankment slope

In order to make full use of coal gangue generated in coal mining and support the carbon neutral policy, the road section K128+573–K128+740 of Anshao Highway (Anhua-shaoyang, Hunan Province)was filled by coal gangue, and the embankment slope was enhanced by gabion net. The basic characteristics of coal gangue were obtained by its chemical composition and gradation, and shear characteristics of gabion reinforced coal gangue were tested by large-scale direct shearing instrument. Finally, the influence of reinforcement and its method on the stability of reinforced coal gangue embankment was found out by finite difference method. The experimental results show that after getting crushed and compacted, curvature coefficient changed from 4.20 to 1.28, which is basically meet the requirements of road filling. When reinforced by gabion, the internal friction angle of coal gangue increased from 35.0° to 40.2°, which helped reducing the attenuation rate of residual strength of coal gangue. The horizontal displacement of the slope foot significantly reduced after the gabion net was reinforced, which effectively restrains the deformation of the side slope, and as the height of the embankment increases, the reinforcement effect becomes more obvious. The smaller vertical distance of gabion net was, the safer of the gangue embankment slope would be, but there is an optimal value for the horizontal laying length. For this program, the optimal length and vertical spacing of gabion net was 8 m and 3 m. As the elastic modulus of coal gangue changed, the safety factor of embankment slope was nearly the same. When the tensile modulus of the gabion net increased, the safety factor of the slope would increase significantly.