格宾网加筋煤矸石界面剪切特性及路堤边坡稳定性研究

为充分利用采煤过程中的废弃物煤矸石，并支持我国碳中和政策，湖南安邵高速公路K128+573—K128+740填方路段采用煤矸石进行填筑，并以格宾网加筋来增强煤矸石路堤边坡的稳定性。基于煤矸石化学成分、级配情况掌握其基本特性，并通过大型直接剪切仪获得格宾网加筋煤矸石的界面剪切特征。借助有限差分软件分析加筋及加筋方式对加筋煤矸石路堤稳定性的影响。结果表明:击实后煤矸石的颗粒级配得到有效改善，曲率系数从4.20变为1.28，有助于满足路堤填筑要求；通过格宾网加筋，煤矸石内摩擦角从35.0°增至40.2°，残余强度衰减率降低；煤矸石路堤边坡坡角水平位移显著减小，有效约束了边坡的变形，且随着路堤高度的增加，加筋效果更为明显；格宾网铺设间距越小，煤矸石路堤边坡安全系数越高，其横向铺设长度存在最优值；对于本工程而言，建议加筋间距、长度分别为3、8 m。随着煤矸石弹性模量的改变，其加筋边坡的稳定性变化并不明显；而当增大格宾网筋材的拉伸模量，格宾网加筋煤矸石路堤边坡的稳定性显著增大。 

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.