模型维数对岩土离散元试验影响的宏-微观研究

Macro-Micro Research on the Influence of Model Dimension to Soil Behaviors in DEM Tests

对实验室常规三轴试验分别进行了二维和三维的离散元数值试验,从试样宏观力学响应和剪切带演化的角度比较模拟结果,分析模型维数对岩土力学性质模拟结果的影响。数值试验结果表明,最密实状态的、具有相同参数的二维和三维试样,在剪切过程中均会表现出软化特性,试样峰值应力均随围压的提高而增大,其峰值应力的数值相近,但三维数值试样达到峰值应力所对应的应变约为二维试样的1/4。随着围压的增大,二维和和三维离散元数值试样剪切带均趋于集中;但在相同围压作用下,不同维数数值试样宏观剪切带的形状和厚度均不同,二维试样剪切带的范围和厚度均较大。

2D and 3D DEM were both employed in the conventional triaxial test simulation to figure out the influence of model dimension on the numerical results of soil behaviors. The differences of 2D and 3D DEM test results were caused by the dimension when 2D and 3D specimens had the same density state（ the minimum void ratio） and parameters. Numerical simulation results indicate that,stress-stain curves of most compacted 2D and 3D specimens show obvious softening characteristics,the strains corresponding to peak strength of 3D specimens are smaller,and about 1 /4 of strains for 2D specimens. The peak strength increases with the increasing confining pressure,the peak strength of 3D specimen under high confining pressure is larger than the peak strength of 2D specimen. With confining pressure increasing,shear bands of both 2D and 3D numerical specimens become concentrated. However,the shape of shear bands of 2D and 3D specimens are different under the same confining pressure level,and the range and thickness of 2D specimens are bigger than those of 3D specimens.