基于颗粒流程序的真三轴应力状态下堆石体的变形和强度特性研究

Stress and deformation analysis of rockfill in true triaxial stress conditions based on PFC

采用三维颗粒流程序,模拟了堆石体的真三轴试验,不仅研究了堆石体在三维应力条件下的宏观应力变形特点,而且将细观与宏观参数联系起来,进一步完善了对堆石体的研究。试验过程采用等中主应力比路径加载。通过比较堆石体真三轴颗粒流模型试验和室内真三轴试验结果,表明颗粒流程序能较好地模拟堆石体的力学特性。颗粒流数值试验结果表明,中主应力对堆石体在三向应力状态下的强度和变形特性均有显著的影响。应力比参数b从0～1变化过程中,中主应力面先压缩后膨胀,小主应力面一直处于压缩状态;中主应力对内摩擦角、弹性模量和泊松比也均有影响。从细观上看,围压越高,b值越大,颗粒配位数越大,孔隙率越小,故从细观角度解释了堆石体的宏观应力变形现象。

Three-dimensional particle flow code（PFC）is adopted to simulate the true triaxial tests of rockfill.Not only the macro stress and deformation characteristics of the rockfill under three-dimensional stress conditions are researched,but also the micro and macro parameters are then linked with each other in order to further improve the study of rockfill.In the process of the test,the ratio of intermediate principal stress is fixed.By comparing the results of rockfill true triaxial test based on PFC and the results of true triaxial test in laboratory,we find that the PFC can suitably simulate the mechanical properties of rockfill.The PFC numerically experimental results indicate that the intermediate principal stress has a remarkable influence on the strength and deformation of rockfill under the three-dimensional stress condition.When stress ratio parameter change from 0 to 1,the intermediate principal stress surface compresses firstly and inflates later;the minor principal stress surface is always on the compression state.The intermediate principal stress is influences on the internal friction angle,the elasticity coefficient and the Poisson＇s ratio.In a mesoscopic view,we find that the higher confining pressure is,the higher value of b is,the greater particle coordination number is,and the smaller porosity factor is.The rockfill macroscopic stress and deformation phenomena are explained from microscopic angle.