三维梁-颗粒模型在岩石材料破坏模拟中的应用

用三维梁-颗粒模型BPM3D(beam-particlemodelinthreedimensions)对岩石类非均质脆性材料的力学性质和破坏过程进行了数值模拟。梁-颗粒模型是在离散单元法基础上,结合有限单元法中的网格模型提出的用于模拟岩石类材料损伤破坏过程的数值模型。在模型中,材料在细观层次上被离散为颗粒单元集合体,相邻颗粒单元由有限单元法中的弹脆性梁单元联结。梁单元的力学性质均按韦伯(Weibull)分布随机赋值,以模拟岩石类材料力学参数的空间变异性。材料内部裂纹通过断开梁单元来模拟。通过自动生成的非均质材料模型对岩石类材料的破坏机理进行研究。岩石类非均质脆性材料在单轴压缩状态下破坏过程细观数值模拟结果显示,岩石材料宏观破坏是由于其内部细观裂纹产生、扩展、贯通的结果。通过数值模拟结果之间的对比分析,揭示出岩石试样宏观破坏模式随细观层次上韦伯分布参数的变化而不同。与实际矿柱破坏形态的对比分析表明了模型的适用性。根据数值模拟结果对岩石类非均质材料的破坏机理进行了探讨。

3-D beam-particle model for simulating fracture in rock material

A 3-D numerical model BPM3D (beam-particle model in three dimensions) is developed to simulate the mechanical properties and fracture process of anisotropic brittle material like rocks. This numerical method used simulating damage and fragmentation phenomena of rock-like material is presented on the basis of discrete element method (DEM) and lattice model that belongs to the finite element method (FEM). Material is schematized at mesoscale level as a three dimensional assembly of particle elements in the BPM3D and the nearest neighboring particles are connected through a lattice of elastic beam elements of FEM. The mechanical properties of beams in BPM3D are randomly allocated according to Weibull distribution to reflect the spatial variation of mechanical parameters in brittle rocks. Cracks in material are simulated through breaking beam elements. Compact and anisotropic synthetic media are generated automatically and are used to investigate the mechanical behavior of the low-porosity material like rock. The numerical simulation results of anisotropic brittle rock fracture process under uniaxial compression show that the initiation, propagation and linking each other in the rock samples at mesoscale level produce the macro-failure of rock samples. It has been revealed by the comparison of numerical simulation results that the macro-failure modes of rock samples are different according to parameters of Weibull distribution at mesoscale level. The comparison with failure modes of pillars in underground mines proves how highly appropriate this method is. The fracture mechanism of anisotropic brittle rock has been discussed based on the numerical simulation results.