垮塌区隐患资源爆破开挖变形响应的DDA法

Discontinuous Deformation Analysis Method for Deformation Response of Hidden Resources in Collapse Area under Blasting Excavation

针对地下金属矿山垮塌区隐患资源开采的安全问题,应用非连续变形分析法(DDA)研究垮塌区隐患资源在爆破动荷载作用下的变形响应.通过势能极小化原理和平面应变假设探讨DDA法的计算过程,在DDA模型中引入自由场边界和设置边界单元体的法向与切向自由阻尼器来模拟垮塌区边缘采场的爆破开挖,讨论了注浆加固后的垮塌区滑移面附近区域在爆破动荷载作用下的变形特征.研究结果表明:DDA模型中的输入波表现出明显的滞后性,根据输入波的滞后性计算波的传播速度与现场实测结果非常接近;爆破开挖后垮塌区滑移线下部区域的变形明显小于上部区域,与实际开挖后现场的监测结果相符合;距离爆源越远的监测点,速度放大系数越大,在DDA法中引入自由场边界和边界单元的自由阻尼器来研究垮塌区边缘采场在爆破动荷载作用下的变形响应是可靠的.

Aiming at the safety problem of hidden resources mining in collapse area of underground metal mines,the discontinuous deformation analysis(DDA)is used to address the deformation response of hidden resources in collapse area under blasting dynamic load.The calculation process of DDA method is stated using the minimization principle of potential energy and plane strain assumption.Meanwhile,free field boundary is inserted in the DDA model and the tangential free damper and normal free damper of boundary units are used to discuss the deformation response of blasting excavation after grouting reinforcement near the collapse area.Results show that the input wave in the DDA model is characterized by obvious hysteresis,and the wave propagation velocity computed considering the hysteresis is consistent with the measured results.Modelling results after excavation indicate that the deformation under the slip line of collapsed zone is clearly less than that above the slip line,which is consistent with the actual monitoring results after excavation.Moreover,the velocity amplification coefficient of monitoring points in the collapsed zone increases with increasing distance from blasting source.Therefore,it is reliable to introduce free-field boundaries and the free dampers of boundary units into the DDA model to study the deformation response of stopes at the edge of collapse area under blasting dynamic load.