节理岩体爆破的颗粒流离散元的模拟研究

Simulation Study of Blasting of Jointed Rock Mass Using PFC

节理在浅表岩体中的存在具有普遍性、多样性及复杂性。由于节理与岩石波阻抗的差异,使得节理对爆破能量具有一定的吸收、反射作用,从而改变了能量的传播路径及正常衰减规律,进而影响爆破效果。为定量研究不同节理分布形式对爆破能量传播的影响程度,本文采用LS-DYNA软件及PFC程序相结合的方法建立节理岩体爆破模型,对爆破发生过程中关键点速度峰值进行分析。结果表明:节理的存在加大了岩体对能量的正常衰减作用,并且衰减程度随能量透过节理数量的增加而增大;当节理经过药包位置并通向临空面时,能量从药包处外泄,爆破效果也会明显降低;节理与药包最小抵抗线的相交位置也会影响其对能量的衰减效果,当节理分别与药包最小抵抗线和其延长线相交时,后者对能量的衰减作用更加明显。

The existence of joints in the surface rock is universal,diverse and complex.Due to the difference of wave impedance in joint and rock,the joint may absorb and reflect the blast energy,and change the propagation path of energy,and further change the normal propagation law.Therefore,the joint can affect blasting effect greatly.In this study,the LS-DYNA and PFC software were used to establish joint rock blasting model to study the impact of blasting energy spread in different types of joint and the peak velocity of key point in blasting.Results show that the attenuation of energy in the jointed rock mass was more great than in intact rock,and the attenuation degree became more and more obvious as the increased number of joints ; when joints passed through the explosion source and reached the free face,the energy could be spilled from the explosion source,which reduced the blasting effect significantly.The intersection point position of joints and minimum burden line also played a role in attenuation effect.When the joints intersect with the extended line of minimum burden line,the energy attenuation effect would be more apparent.