采动斜坡覆岩垮落规律及变形破坏预测研究

    Study on overburden strata collapse law and deformation-failure prediction of mining-induced slopes

    • 摘要: 针对中国西南山区“上硬下软”结构斜坡在采动扰动下的灾变机制与跨尺度预测难题,以贵州发耳煤矿五盘区为研究对象,揭示覆岩垮落与斜坡变形的动态耦合机制,构建空天地协同的灾害全生命周期预测技术体系。基于50106采区9个总长850 m的采空区,采用离散元数值模拟、差分干涉测量短基线集时序分析技术(SBAS−InSAR)和野外地质调查融合方法,建立高727 m、宽1527 m的离散元模型,设置15个位移监测点模拟动态开挖过程;通过位移场分析、地表形变反演与野外验证,阐明了“覆岩垮落−裂隙扩展−地表滑移”链式响应规律。研究定量揭示了采动覆岩裂隙“形成−扩张−压实闭合”的周期性扩展机制,顶板最大沉降3.03 m、地表水平位移峰值1.64 m;SBAS−InSAR监测显示,地表最大年变形速率44 mm/a的高风险区,与数值模拟预测的潜在滑动面(高程950~980 m)空间重叠显著;建立包含自然演化、覆岩垮落、缓慢变形、累进变形及整体失稳的五阶段地质力学模型,其中覆岩垮落阶段裂隙带高度达20.5 m,缓慢变形阶段出现0.15 m反向位移,累进变形阶段位移梯度达1.2 m/hm。结果表明:垮落带高度模拟值18~22 m,与钻孔实测值误差<13%;斜坡呈现非对称位移场特征,地表水平位移梯度达到0.8 m/hm,是坡体内部的4倍;构建InSAR−无人机−数值模拟协同预警技术,划分高、中、低危险区,其中高危险区潜在滑动面失稳体积达900 m3。研究阐明了“顶板离层−砌体梁断裂−坡体推挤”力学传导机制,通过协同技术实现从千米级采空区到厘米级地表变形的跨尺度灾害预警。

       

      Abstract: 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 reaches 1.2 m/hm in the progressive deformation stage. The results show that the simulated value of collapse zone height is 18-22 m, and the error between the simulated value and the measured value is less than 13%. The slope presents the characteristics of asymmetric displacement field, and the surface horizontal displacement gradient reaches 0.8 m/hm, which is 4 times that of the slope interior. The INSAR-UAV-numerical simulation collaborative early warning technology was constructed to divide the high, medium and low risk zones, among which the potential sliding surface instability volume in the high risk zone reached 900 m3. The mechanical transmission mechanism of “roof separation, masonry beam fracture and slope extrusion” is studied, and the cross-scale disaster warning from kilometer-level goaf to centimeter-level surface deformation is realized through collaborative technology.

       

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