数值分析法确定露转坑岩层移动范围

 随着浅部矿产资源的枯竭，中国许多露天开采已经或即将转入地下开采，或露天与地下联合开采。合理确定岩层及地表的移动，为露转坑设计和安全生产提供依据是露转坑联合开采首先要解决的重要课题之一。为了验证永平铜矿露天转地下开采工程设计的合理性，为后续安全生产提供参考，采用三维有限差分数值模拟计算方法，系统地分析永平铜矿II、IV号矿体在不同开采水平的岩体移动变形、地表位移变化及露采边坡稳定状态，给出了相应开采水平的岩体及地表移动变形特征、最大垂直和水平位移，以及岩体移动角。结果表明，II号矿体对岩层移动的影响远大于IV号矿体；最大垂直和水平位移均在II号矿体上部东部边坡岩体中；合理的开采顺序应是先采Ⅳ号矿体，后采II号矿体；模型局部地段处于破坏或极限稳定状态，但随开采深入，露采边坡整体处于稳定状态，因此矿山采用的矿房回采嗣后充填采矿方法合理可行。用FLAC3D数值模拟方法研究露转坑联合开采的岩层移动规律，反映了岩体应力、变形的客观过程，为露转坑矿体开采岩层移动范围确定提供了一条新的途径。

Range of Rock Movement in Transition from Open Pit to Underground Mining Determined by Numerical Method

With the depletion of shallow mineral resources, many open pits have been already or shall soon be switched to underground mining. The safety design of open pit stoppage combined with the opening of underground mine involves many problems. In this paper, FLAC3D is used to systematically analyze the rock layer movement and deformation. Surface displacements of ore-bodies II and IV at different mining levels are discussed. With the determination of parameters of rock layer movements, the open pit slope stability of Yongping copper mine is analyzed. The corresponding movement characteristics of rock mass, maximal vertical and horizontal displacements as well as rock movement angles are obtained. Results show that the influence of ore-body II on the rock layer movement is far greater than that of ore-body IV. The maximum vertical and horizontal displacements all occur in the rock mass located on the eastern slope of ore-body II. The reasonable mining sequence should be ore-body IV first and ore-body II second. A part of the model area is in the state of breakage and limit stability. However, the open pit slope is in an integral stability state as the mining advances. It is shown that the filling method used in the next stage in the mine is feasible. The rock layer movement during the open pit stoppage combined with the opening of the underground mine, simulated by using FLAC3D, gives a true picture of the stress and displacement states of the rock mass.