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针对颗粒流法中颗粒几何参数等对土体宏观力学性质的影响进行了数值模拟,并将数值模拟结果与室内模型试验验证进行了对比。对二维、三维下土体级配及孔隙率进行了理论分析,并提出二维数值试样颗粒数目及孔隙率转换公式。采用PFC2D软件进行了6组参数验证及24组交叉对比(含4组级配、3组孔隙率及2类接触模型)双轴压缩试验。结果表明:孔隙率对土体力学性质的影响大于级配;随着孔隙率增加,土体强度峰值逐渐降低,对应轴向应变增大,体应变则由剪胀性逐渐向剪缩性过渡。当孔隙率较低时,采用线性及Hertz-Mindlin(H-M)接触模型得到的模拟结果均较接近;而当孔隙率升高时,建议采用H-M接触模型,以更好地反映土体到达强度峰值后产生的后续剪胀效应。
The numerical simulation of the influence of particle geometry parameters on the macroscopic mechanical properties of the soil is carried out. The numerical simulation results are compared with the indoor model tests. The two-dimensional and three-dimensional soil gradation and porosity were theoretically analyzed, and the number of two-dimensional numerical sample and the porosity conversion formula were proposed. Six groups of parameters were validated by PFC2D software and biaxial compression tests of 24 groups (including 4 groups grading, 3 groups of porosity and 2 types of contact models) were carried out. The results show that the influence of porosity on the mechanical properties of soil is greater than that of grading. With the increase of porosity, the peak value of soil strength gradually decreases and the corresponding axial strain increases. The bulk strain gradually changes from shear dilation to shear shrinkage. When the porosity is low, the simulation results obtained by the linear and Hertz-Mindlin (HM) contact models are close to each other. When the porosity is high, HM contact model is suggested to better reflect the peak soil strength of arrival After the resulting dilatancy effect.