Overlying strata movement and surface deformation through roof cutting and pressure relief: Geomechanics model and field tests

Abstract The Self-formed roadways by roof cutting and pressure relief (SF-RCPR) represents a novel approach that eliminates the need for coal pillars by naturally creating roadways through Roof Cutting Pressure Relief (RCPR) technology. This study investigates overlying strata movement and surface deformation in the 5-200 working face of the Dianping Coal Mine, using geomechanics model tests. Key monitoring techniques include infrared thermal imaging, digital image correlation (DIC), static strain gauges, and sketches. The findings reveal that overlying strata movement during mining can be categorized into distinct stages: finite deformation, immediate roof collapse, main roof breaks and rotates, and overlying strata stabilization. The strata form a complete caving zone, fractured zone, and slow subsidence zone, effectively eliminating the bending subsidence zone. Rock strata subsidence curves exhibit “S-type”, “exponential”, and “similar S-type” patterns. Infrared thermal images reveal varying temperature zones corresponding to overburden movement “three zones”, with notable differences between the roof cutting and non-roof cutting sides. During the immediate roof collapse, the temperature dropped by 1.8 °C, then rose by 0.6 °C as the main roof collapsed. Field measurements of surface cracks under the SF-RCPR were compared to those under the traditional longwall mining method (TLMM). Even after three mining disturbances, crack widths under SF-RCPR remained mostly between 0.01 and 0.2 m, with depths primarily ranging from 0.1 to 0.2 m, resulting in minimal ground damage. These findings deepen the understanding of overburden movement under SF-RCPR and demonstrate its effectiveness in minimizing surface damage.