INFLUENCES OF MINING DISTURBANCE ON STABILITY FOR RAILWAY EMBANKMENTS OF COAL GANGUE

The conventional triaxial test and the improved triaxial test are mainly used to study change laws of mechanical properties for soil in mining areas before and after being disturbed by mining. Based on the results of the triaxial tests subjected to lateral unloading or loading and the attenuation characteristics of physical and mechanical parameters for coal gangue under the coupling effects of natural factors, soft foundation and mining influence, the evolution laws of stability for railway embankments of coal gangue in subsidence zones affected by mining were researched. The results showed that under the influences of mining, the mechanical indexes of the foundation soil decreased, the reduction factor for soft soil was about 0.9 to 1.0, and the reduction factor was 0.6 to 0.7 for other soil. The overall and local stability analysis showed that the safety factors of embankments for coal gangue on conventional foundation conditions were the largest at the same groundwater level, the safety factors of embankments of coal gangue on soft foundation decreased sharply due to being mined. Under the same foundation conditions, the higher the level of groundwater, the samller the safety factors of embankments, the stability to embankments of coal gangue on soft foundation affected by mining was lower when the groundwater level was higher than 5 m, the safety factors of embankments could not meet the Code for Design on special Railway Earth Structure TB 10035-2018. Therefore, under the coupling action of rainwater and weathering, embankments in the subsidence zone should be reinforced.