Study on Crack Evolution Mechanism of Roadside Backfill Body in Gob-Side Entry Retaining Based on UDEC Trigon Model

Gob-side entry retaining is a non-chain pillar mining technology in which reasonable roadside support is important for efficient roadway maintenance and goaf isolation in coal mines. A UDEC Trigon model is adopted in this paper to study the mechanism of crack expansion and evolution at various distances from the working face. This is done to optimize parameters for the roadside backfill body (RBB) by combining emergence, development and aggregation of micro-cracks with macroscopic mechanical responses. Results of the model show that cracks first appear in the top and bottom corner of the roadway in the lane-side RBB. Damage to the RBB is mainly caused by tensile cracks, which can be divided into main and secondary crack-development and yield-bearing zones. A reasonable aspect ratio of the RBB can greatly increase the area of the yield-bearing zone and reduce the damage degree, while reducing the number of penetrating cracks and preventing generation of seepage channels. The application of this model for gob-side entry retaining in the intake airway of the N2105 working face in the Yuwu coal mine indicates that deformation of the surrounding rocks can be effectively controlled.