Study on the Fracture Characteristics of Key Rock Strata Under Overlying Obliquely Intersected Remnant Coal Pillars

In close-distance coal seam mining, the concentrated stress from overlying obliquely in-tersected remnant coal pillars significantly impacts the mining of underlying coal seams. Taking the mining of Panel 22208 in the 2-2 coal seam beneath the Huojitu Mine of Da-liuta Coal Mine as the engineering case, this study established an elastic thin plate me-chanical model with two elastically clamped boundaries and two elastically simply sup-ported boundaries under the concentrated stress of overlying obliquely intersected rem-nant coal pillars (nonlinear load Q), based on theoretical analysis and elastic thin plate mechanics theory. The mechanical and fracture characteristics of key rock strata were in-vestigated when the working face was located at 0 m, 20 m, 40 m, and 60 m within the in-fluence range of remnant coal pillars. The results indicate: (1) The spatial sequence of ini-tial fracture in key rock strata is: coal wall side ahead of the working face → coal wall side behind the working face → solid coal side → central area of the working face → coal pillar side. (2) Under nonlinear load Q, a critical transition occurs at 40 m within the influence range of remnant coal pillars. The absolute value of maximum principal bending moment shifts from dual-peak maxima at both sides to a single-peak maximum at one side, with an overall increase of 12%. (3) The concentrated stress from overlying obliquely intersect-ed remnant coal pillars (nonlinear load Q) is the primary factor altering the fracture se-quence and angles of key rock strata, demonstrating significant influence on their fracture characteristics.