诱导顶板崩落时变力学模型的建立与应用

运用时变力学理论,针对大厂铜坑矿顶板诱导崩落试验采场的地质特征,建立有限元基本方程和时变力学模型,采用多步骤开挖的准时变力学有限元方法,模拟不同顶板诱导失稳崩落模式下的塑性区发展、东西预裂硐室与崩顶硐室的安全系数,对比研究确定顶板诱导可控失稳崩落的诱导模式,即先预裂爆破后切顶诱导崩落,其塑性区主要控制在东西两条预裂缝之间,垂直向达到顶板上方58m处,最小安全系数为1.1。采用数字式全景钻孔摄像技术,对铜坑矿顶板诱导崩落实验采场的顶板围岩诱导效果进行可视化监测。发现生成20～40mm宽的预裂缝,在顶板围岩中出现大量"X"型次生裂隙。实践结果表明,该模式可以有效地实施顶板的诱导可控失稳崩落。

Application and establishment of time-varying mechanical model to induction caving roof

FEM(Finite element) basic equations were built according to the theory of the time-varying mechanics.Based on the geology and the ore physical mechanical properties and characteristic,the time-varying mechanical 2D FEM model was built in the testing stope of the Tongkeng Mine,and the time-varying mechanical behavior was simulated by the method with many steps.For the two kinds of modes of the induction caving roof,the expanding of the plastic zone and the safety factors were analyzed in the tunnel,the effects were analyzed for the safety of the stop and the influences of the mine technology.The results show that it is advantageous to induction caving roof,where there occurs the first pre-splitting blasts and then forced cutting roof caves.To the mode,the plastic zone is controlled between the east and west preblasting crack,and the height is 58 m above the emptied areas,the minimal safety factor is 1.1.According to the results,it is proposed that the millisecond blasting should be between the first pre-splitting blasting bolts and the last bolts in the same time.Digital panoramic borehole camera technique can be used to detect the crack development and evaluate the induction caving mode effect.In the East and West Presplitting Tunnels,the presplitting cracks are found,and its width is 20-40 mm.At the same time,a large number of "X" secondary cracks are formed in the roof.The results prove that it is advantageous to control the mode of induction caving roof.