多块体形状堆石体碾压颗粒破碎数值模拟

通过6种典型堆石块体的形状近似,分别采用两种接触本构模型建立了多块体形状堆石体离散元数值模型,研究堆石体在碾压荷载作用下的颗粒破碎过程,建立颗粒破碎的量化计算方法,分析碾压前、后堆石级配曲线的变化,讨论接触本构模型和颗粒形状对块体破碎的影响。模拟结果显示,碾压荷载下堆石颗粒以张拉破碎为主,随着碾压遍数的增加,局部开始出现剪切破碎;提出的颗粒破碎量化计算方法,在大粒径范围对粒径变化幅度预测偏大,但级配曲线整体趋势与实测结果比较吻合;相比较于接触连接模型,平行连接模型与现场碾压试验结果更接近。6种块体形状的数值结果显示,随着形状系数的增加,在其他条件不变的情况下颗粒破碎率逐渐降低,其中类长方形块体在碾压荷载作用下颗粒破碎最明显。相比较于纯圆颗粒或者单一非圆颗粒,采用的6种颗粒形状建立的堆石体振动碾压离散元模型,更接近现场实际情况。

Numerical simulation of particle crushing for rockfill of different particles shape under rolling compaction

Six typical shapes of rockfill were selected and simulated by clusters of round particles. Two kinds of contact constitutive models were adopted to establish multi-shape numerical model of rockfill. The process of particles crushing under vibration compaction was simulated and the mechanism of crushing was discussed. A quantitative calculation method of crushing was proposed, which can be used to analyze the variation of grain size distribution curve before and after particle crushing. The effect of different contact constitutive models on the numerical results was also discussed in detail. The numerical results indicate that the tensile cracking is dominated and the shear failure zone appears only after several numbers of vibration rolling compaction. Although the crushing ratio calculated from the proposed quantitative calculation method results is higher than the test data for the large particles; the grain size distribution curve predicted from the numerical method has a good agreement with the test results on the whole. The predicted results from the numerical models of parallel-bounded law are more rational than that from the contact bounded model. The numerical results from the 6 shapes models indicate that the crushing ratio decreases with the increasing of shape coefficients. The rectangular particles are more fragile than other shapes. These study results of different particle shapes indicate the numerical model consists of 6 different shapes are more rational than pure round particles or single non-round particles.