科研之友
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摘要
Triaxial samples of railway ballast have been modelled using clumps of spheres. The bulk of the clump is formed from ten balls in a tetrahedral shape. The interlocking and breaking of very small asperities which find their way into the voids is modelled using weak parallel bonds between clumps. The interlocking and fracture of larger asperities has been modelled by bonding eight small balls to the clump. Monotonic tests have been performed on triaxial samples under a range of confining pressures from 15 kPa to 240 kPa and the results compared with existing experimental data. Tests were also simulated using uncrushable clumps to highlight the important role of asperity abrasion. Cyclic triaxial tests were then simulated on the same aggregates using the same microparameters as the monotonic tests under a range of stress conditions and the results were compared to existing experimental data for the same simulated ballast. The results show that the clumps are able to capture the behaviour of ballast under both monotonic and cyclic conditions and asperity abrasion is shown to play an important role in governing strength and volumetric strain under monotonic loading, and on permanent strains under cyclic loading. The new contribution is therefore to show that it is possible to model a real granular material under static and cyclic conditions, thus providing much micromechanical insight.
- 出版日期2010-6
