Analysis of Stress Evolution Characteristics and Mine Pressure Patterns During Roadway Excavation Under Irregular Goaf Areas
Abstract
To clarify the stage-dependent stress superposition in gob-side roadways beneath irregular overlying goafs, the #52109 material roadway was investigated using a MATLAB-based analytical stress-transfer model, key-strata mechanics, FLAC3D simulation, and field monitoring. The analytical results revealed an approximately elliptical “stress-bubble” distribution with a maximum increment of 4.82 MPa beneath the overlying remnant coal bodies and a second roof-induced stress peak of 1.22 MPa at 14.88 m from the adjacent goaf boundary, governed mainly by Sub-key Strata 2 and 3. At the actual vertical separation of 71.5 m between the roof of the #52109 material roadway and the base of the overlying goaf, the two stress-component curves calculated in MATLAB intersected at 59.1 m from the projected boundary of the overlying remnant coal body, defining a site-specific transition between the dominant stress sources. Beyond 59.1 m, the lateral abutment stress induced by the #52107 goaf was dominant; within this distance, the downward-transmitted stress from the remnant coal body increased rapidly and was superimposed on the lateral abutment stress. The analytical and FLAC3D models predicted maximum total vertical stresses of 32.19 and 32.51 MPa, respectively, with a difference of 0.32 MPa (0.99%); the numerical model also qualitatively reproduced the corresponding spatial transition in the stress pattern. The combined results identified the sections 250–485 m and 680–1305 m from the roadway entrance as high-hazard zones. After targeted large-diameter borehole destressing and roof pre-splitting blasting were implemented, field monitoring recorded a maximum side deformation of 77.9 mm, while low-energy seismic events accounted for 94.33% of all monitored events. These findings provide a quantitative basis for hazard zoning and regional pressure relief in gob-side roadways beneath irregular overlying goafs.