基于连续-非连续单元方法的露天矿三维台阶爆破全过程数值模拟

爆破开采是露天矿采选总成本控制的首要环节，数值模拟是进行露天矿爆破开采优化设计及爆破效果分析的有效手段。利用连续-非连续单元方法（continuum-discontinuum element method，CDEM）对露天矿的三维台阶爆破过程进行了模拟，通过朗道爆炸模型实现了爆炸作用力的精确计算，通过弹性-损伤-断裂本构实现了岩体损伤破裂过程的描述，通过半弹簧-目标面及半棱-目标棱的联合接触算法实现了破碎岩块碰撞、飞散及堆积过程的高效模拟。开展了小尺度单自由面爆破过程的数值模拟，计算给出的块度分布曲线、爆破漏斗体积等参数与文献中模型实验的结果基本一致，证明了CDEM及本文所述各类模型在模拟爆炸破岩方面的精确性。以鞍千矿南采区的露天铁矿爆破开采为研究对象，建立了3排21炮孔的三维台阶爆破概化模型，模拟了从炸药起爆、岩体损伤破裂到最后爆堆形成的全过程；计算结果表明，除后缘拉裂槽外，数值计算给出的爆堆形态、顶部鼓起高度等与现场的测试结果基本一致，证明了利用CDEM开展三维露天台阶爆破全过程模拟的可行性。

Numerical simulation on complete process of three-dimensional bench blasting in an open-pit mine based on CDEM

Blasting mining is the most important part of the total cost control in an open pit mine, and numerical simulation is an effective method to optimize the design of blasting mining and to analyse blasting effect. By using the continuum-discontinuum element method (CDEM), the three-dimensional bench blasting process of the open pit mine is simulated. The Landau explosive model is adopted to precisely calculate the blasting effect, and the elastic-damage-fracture constitutive law is used to describe the damage and fracture process of rock. By adopting the semi-spring target face and semi-edge target edge combined contact algorithm, the collision, flying and accumulation process of large number of fragments is simulated efficiently. The numerical simulation of the small scale blasting process with the single free surface is carried out. The block distributing curve and volume of the crater obtained by numerical simulation are more or less the same as those obtained by experiment, which demonstrates that CDEM and corresponding models described in this paper are good at simulating the rock blasting process. Based on the blasting technology in the south region in Anqian open-pit mine, a generalized three-dimensional bench blasting model with 3 rows and 21 bore holes is set up, and the complete process from explosive detonation to muckpile formation is carried out. Numerical results show that, except the tensile crack behind the blasting area, the muckpile shape and heaving height obtained by numerical simulation are accordant with the ones obtained by field test to some extent, which demonstrates the feasibility to simulate the three-dimensional bench blasting by CDEM.