This study highlights the effects of strain rate on the critical state (CS) response of crushable sand. A set of drained triaxial tests is simulated using the discrete element method (DEM) to understand the rate effects on the stress–strain and volumetric behaviour of the granular sample. The DEM parameters are obtained by comparing the stress–strain and particle crushing behaviour of in-house experimental analysis on crushable coral sand under a slow strain rate. In DEM, the particles are subjected to varied strain rates under different initial confining pressures and initial densities to capture the rate effects on macroscopic responses until the CS. It is observed that crushing increases with an increase in confining stress. However, a higher strain rate induces relatively lower crushing and higher strength in terms of both peak stress and residual stress. It is observed that in pressure–volume space, the CS line alters with the increasing strain rate of the crushable samples, especially under high-confining conditions, whereas the effect of strain rate on CS seems to be negligible under low-confining conditions due to the absence of particle crushing.

中文翻译：

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应变率对可碎砂临界状态影响的数值评价

本研究强调了应变率对可碎砂临界状态 (CS) 响应的影响。使用离散元法 (DEM) 模拟了一组排水三轴试验，以了解速率对颗粒样品的应力-应变和体积行为的影响。DEM 参数是通过比较慢应变速率下可破碎珊瑚砂的内部实验分析的应力-应变和颗粒破碎行为获得的。在 DEM 中，粒子在不同的初始围压和初始密度下经受不同的应变率，以捕捉到 CS 之前对宏观响应的速率影响。可以观察到，压碎随着围压的增加而增加。然而，就峰值应力和残余应力而言，较高的应变率会导致相对较低的压碎和较高的强度。观察到在压力-体积空间中，CS 线随着可压碎样品应变率的增加而变化，尤其是在高约束条件下，而在低约束条件下，应变率对 CS 的影响似乎可以忽略不计，因为没有颗粒破碎。