郑州大学学报（理学版）

基于连续-非连续单元方法(CDEM),通过在单元中引入线弹性模型,在虚拟界面中引入内聚力模型,实现了外加载荷下岩体损伤破裂过程的模拟.基于霍普金森杆(SHPB)实验的基本原理,建立了直径为50 mm、厚度为25 mm的赤铁矿数值试样模型.借助CDEM探讨了加载应变率为40、80、120、160、200 s-1五种工况下数值试样的动态本构曲线、动态单轴抗压强度、能耗密度、试样破裂度及特征破碎尺寸,获得了与相关SHPB实验基本一致的结果.结果表明:在单元本构及虚拟界面本构中未引入应变率效应的情况下,数值试样的动态单轴抗压强度仍然表现出较强的应变率相关性;随着加载应变率的增加,试样峰值强度按幂函数形式从277 MPa增大至310 MPa,数值试样中用于损伤破裂的能耗密度增大,且能耗密度与试样破裂度及特征破碎尺寸密切相关.

Based on continuous discontinuous element method(CDEM),by introducing linear elastic model for elements and cohesive model for virtual interfaces,the simulation of damage and fracture process of rock mass under the applied load was realized. Based on the basic principle of split Hopkinson pressure bar(SHPB) experiment,a numerical sample of hematite with the diameter 50 mm and thickness25 mm was established. With CDEM,five loading conditions with the strain rate 40,80,120,160,200 s-1were discussed. The dynamic constitutive curves,dynamic uniaxial compressive strength,energy consumption density,fracture degree,and characteristic size of fragment were analyzed,and the results obtained by CDEM were more or less the same as those gotten by SHPB experiment. Although strain rate effect was not considered into constitutive laws of elements and virtual interfaces,the dynamic uniaxial compressive strength of numerical specimen still presented strong strain rate dependence. With the increase of strain rate loaded,the dynamic strength increased from 277 MPa to 310 MPa in power function form; and the energy consumption density for the damage and fracture increased. The energy consumption density was closely related to fracture degree and characteristic size of fragment.