考虑颗粒破碎的砂土高应力一维压缩特性颗粒流模拟

以Toyoura砂室内高应力一维压缩试验结果为基础,利用二维颗粒流方法中的接触黏结模型生成簇颗粒单元来模拟实际砂土的颗粒破碎特性。高应力一维压缩数值试验中,数值试样由887个簇颗粒单元组成。数值试验与室内试验结果对比表明:数值试验得到的压缩曲线形状及颗粒破碎屈服应力大小均与Toyoura砂室内试验结果一致,说明数值试验能够较好地再现实际砂土在高应力一维压缩条件下的颗粒破碎特性。与室内试验相比,利用数值试验不仅能得到宏观的颗粒破碎现象,而且还能通过分析内部接触力的变化和对黏结破裂位置的追踪来研究颗粒破碎的细观演化规律,从而可进一步探讨颗粒破碎的细观力学机制。最后,就细观参数、加荷速率、簇颗粒数量及试样平均粒径等因素变化对数值试验结果的影响进行了分析。

Numerical simulations of particle breakage property of sand under high pressure 1D compression condition by use of particle flow code

Based on the results of high pressure ID compression laboratory tests on Toyoura sand, the cluster element which was formed by the contact-bond model in PFC^2D was used to simulate the particle breakage characteristics of sand under high pressure. The high pressure ID compression numerical tests were executed with the sample consisting of 887 clusters. It was indicated that the compression curve and the yield stress at the beginning of particle breakage achieved from numerical tests were both in good agreement with those of the laboratory tests on Toyoura sand. Compared with the laboratory tests, numerical tests could not only demonstrate the macro phenomenon of particle breakage, most importantly, it could also expose the regularity of evolution of particle breakage microscopically, and would contribute to the further research of the micromechanics of particle breakage. Finally, the sensitivity of the results of numerical tests to the variation of micro parameters, loading velocity, number of clusters and mean duster size, was also investigated.