Research on the Stability Mechanism and Control Technology of Surrounding Rock in Filling Working Face with Gob-Side Entry Retaining

Gob-side entry retaining (GER) in filling working face promotes sustainable mining by preserving roadways for reuse, reducing resource consumption, and minimizing environmental disturbances. This study investigates the deformation mechanism and failure characteristic of the mining roadway during GER in filling working face, using the CT301 headgate at Chahasu Coal Mine as a case study. A UDEC Trigon numerical model was established, and uniaxial compression tests were conducted to calibrate the mechanical parameters of the rock mass and filling material. The deformation, crack distribution, overburden subsidence, and lateral stress were compared under four conditions: caving method and filling rates of 65%, 80%, and 95%. The results showed that compared to the caving method, the filling method can effectively control overburden movement and suppress roadway deformation. As the filling rate increases, the surrounding rock deformation, crack density, subsidence, and lateral stress all decrease. Overall, the 95% filling rate was the most effective, followed by 80% filling rate, 65% filling rate, and then the caving method. After adopting a 95% filling rate at CT301 panel, the maximum deformation of CT301 headgate was only 190 mm, meeting the mine’s production requirements.