Study on overburden strata collapse law and deformation-failure prediction of mining-induced slopes
摘要
Aiming at the disaster mechanism and cross-scale prediction problem of slopes with “hard at the top and soft at the bottom” structure under mining disturbance in the mountainous area of southwest China, this study takes the fifth panel of Fa’er Coal Mine in Guizhou Province as the research object to reveal the dynamic coupling mechanism of overburden strata collapse and slope deformation, and construct a disaster whole life cycle prediction technology system based on the coordination of space-air-ground. Based on 9 goaf areas with a total length of 850 m in 50106 mining area, a discrete element model with a height of 727 m and a width of 1527 m was established by using the intergration method of discrete element numerical simulation, differential interferometric synthetic aperture radar (D-InSAR) small baseline subset (SBAS) time-series analysis technology (SBAS-InSAR) and field geological survey. 15 displacement monitoring points were set up to simulate the dynamic excavation process. Through displacement field analysis, surface deformation inversion and field verification, the chain response law of “overburden strata collapse-fissure expansion-surface slip” is elucidated. The study quantitatively revealed the periodic expansion mechanism of “formation-expansion-compaction closure” of mining overburden fracture, with the maximum roof settlement of 3.03 m and the peak surface horizontal displacement of 1.64 m. SBAS-InSAR monitoring shows that the high risk area with the maximum annual deformation rate of 44 mm/a overlaps significantly with the potential slip surface (elevation 950-980 m) predicted by numerical simulation. A five-stage geo-mechanical model including natural evolution, overburden strata collapse, slow deformation, progressive deformation and overall instability is established. The fracture zone height reaches 20.5 m in the overburden strata collapse stage, 0.15 m reverse displacement occurs in the slow deformation stage, and the displacement gradient