To investigate the influence of blasting disturbances on the surrounding rock of stopes in deep environments, this study developed a numerical model of a deep stope featuring staged longhole drilling, utilizing the discrete element method platform (PFC3D) and based on the engineering conditions of a hard rock mine in southern China. A five-row fan-shaped blast hole configuration was designed, and numerical simulations of millisecond-delayed blasting were conducted. The findings indicate that distinct dynamic response characteristics are observed in various zones of the surrounding rock under multi-row blasting conditions. Notably, the particle vibration amplitudes in the goaf sidewalls initially increase and subsequently decrease as the blast hole row spacing increases. Additionally, the vibration of the roof shows a marked reduction when the spacing exceeds 1.5 meters, whereas the row spacing between 1.0 and 1.5 meters has a relatively minor effect. Significant vibration accumulation is anticipated on the bench face and free surface. Cumulative deformation damage is primarily observed in the left abutment, bench face, and roof of the goaf under blasting loads, while the right abutment exhibits minimal damage. A distinct strip-shaped damage zone is evident on the left abutment, and large-scale rock collapse is likely on the bench face. Field validation corroborates substantial collapse risks in the roof strata and localized damage zones in the left abutment, aligning with numerical predictions. This study offers practical guidance for optimizing blasting design and mitigating disaster risks in deep hard rock mining operations.
数值仿真模型采用颗粒流仿真平台PFC3D进行建模。由于离散单元法能够独立展示岩体的裂纹扩展及岩体变形,其在分析围岩破裂及其致灾过程方面具有较大优势。为此,许多学者选用离散单元法开展围岩稳定性分析。PFC3D是经典离散单元仿真平台,其在计算过程中不需预置材料的本构模型,颗粒之间的运动遵循牛顿第二定律。因此,在计算复杂的动力问题(如围岩爆破响应)时也具有较大优势。如图2所示,在PFC3D中,岩体的力学行为及其构成可由颗粒以及颗粒之间的线性接触和黏结等表征。在本研究中,平行黏结模型被用来模拟岩体的力学行为。平行黏结模型假设颗粒介质之间存在一定的黏结,并通过黏结来传递力和力矩(Qiu et al,2020)。当黏结上的法向应力或剪切应力达到其法向强度或剪切强度时,黏结会发生破坏,并在破坏位置产生新的裂纹。黏结上的最大法向应力和剪切应力如式(1)所示。
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