[论文解读] EFFECT OF PARTICLE SIZE ON THE SHEAR STRENGTH BEHAVIOUR OF SANDS

Mohammad Nurul Islam, Ayesha Siddika+3 more|arXiv (Cornell University)|Jan 1, 2011

Geotechnical Engineering and Soil Mechanics参考文献 8被引用 27

一句话总结

本研究通过在八种不同粒径的均质砂和级配砂上进行直接剪切试验，探讨了颗粒尺寸对砂土剪切强度的影响。结果表明，随着颗粒尺寸增大，内摩擦角和最大剪切应力均升高，级配砂由于颗粒间嵌锁作用增强而表现出更高的强度，理论模型验证了实验趋势。

ABSTRACT

During plastic deformation of granular materials due to loading, the stress-strain and strength characteristics of sand grains are influenced with grain size, their distribution and packing. Also the macroscopic behaviour of granular materials changes with the variation of microscopic behaviour. Particle size is one of the important properties which plays a dominant role on the stress, strain and strength responses of granular materials. Alteration of grain size results in the change of void ratio as well as particle effective contact area revolutionized and the load distribution mechanism of particle to particle contact. To evaluate the effect of particle size, a series of direct shear tests were performed considering uniform particles of eight samples (0.075, 0.15, 0.212, 0.300, 0.600, 1.18, 1.72 and 2.76 mm) and graded particles of two samples (0.075-1.18 mm and 0.075-2.36 mm). Three types of normal loads (0.05, 0.10 and 0.15 kN) were selected for each test. For uniform particles, particles retained on individual sieve size were considered and in graded particles combination of each uniform particle pondered. A theoretical approach was also proposed to correlate the particle size and macroscopic response. From the experimental results it was observed that for each set of normal load with the increase of particle size, angle of internal friction as well as maximum horizontal shear stress increases for uniform sands and a similar response was noticed in graded sands but the larger the gradation the higher the shear strength. Maximum horizontal shear and angle of internal friction with respect to particle size is also influenced by normal stress. Experimental results have good agreement with the theoretical approach.

研究动机与目标

• 量化颗粒尺寸对颗粒材料剪切强度行为的影响。
• 研究颗粒尺寸如何影响砂土在不同法向应力下的内摩擦角和最大水平剪切应力。
• 评估颗粒级配在改变宏观剪切强度响应中的作用。
• 建立并验证一个将颗粒尺寸与宏观力学行为相关联的理论模型。

提出的方法

• 对八种粒径范围为0.075 mm至2.76 mm的均质砂样进行了系列直接剪切试验。
• 对两种级配砂样（0.075–1.18 mm 和 0.075–2.36 mm）进行了额外试验，以评估级配的影响。
• 对每种样品施加三种法向应力（0.05、0.10 和 0.15 kN），以研究应力依赖性行为。
• 通过筛分保留的单个粒径颗粒确保均质样品的均匀性，并将不同粒径组合用于级配样品。
• 提出一个理论模型，以关联颗粒尺寸与宏观剪切强度响应。
• 将实验结果与理论预测进行对比，以验证模型。

实验结果

研究问题

• RQ1 在不同法向应力下，颗粒尺寸如何影响均质砂的内摩擦角？
• RQ2 颗粒尺寸对颗粒材料最大水平剪切应力有何影响？
• RQ3 与均质颗粒相比，颗粒级配如何影响砂土的剪切强度？
• RQ4 法向应力在多大程度上调节颗粒尺寸与剪切强度之间的关系？
• RQ5 理论模型能否准确预测基于颗粒尺寸的宏观剪切强度响应？

主要发现

• 对于均质砂，颗粒尺寸增大时，所有法向应力条件下内摩擦角均升高。
• 在均质砂中，最大水平剪切应力随颗粒尺寸增大而增加，表明其承载能力增强。
• 级配砂由于颗粒间嵌锁作用增强和有效接触面积增大，表现出比均质砂更高的剪切强度。
• 在较高法向应力条件下，颗粒尺寸对剪切强度的影响更加显著。
• 所提出的理论模型与实验数据吻合良好，验证了颗粒尺寸与宏观力学响应之间的相关性。
• 颗粒尺寸影响孔隙比和载荷传递机制，从而影响整体剪切强度行为。