When grains are added to a cylinder, the weight at the bottom is smaller than the total weight of the column, which is partially supported by the lateral walls through frictional interactions with the grains. This is known as the Janssen effect. Via a combined experimental and numerical investigation, here we demonstrate a reverse Jansen effect whereby the fraction of the weight supported by the base overcomes one. We characterize the dependence of this phenomenon on the various control parameters involved, rationalize the physical process causing the emergence of the compressional frictional forces responsible for the anomaly, and introduce a model to reproduce our findings. Contrary to prior assumptions, our results demonstrate that the constitutive relation on a material element can depend on the applied stress.

中文翻译：

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窄颗粒柱中的反向詹森效应

当将谷物添加到圆柱体中时，底部的重量小于圆柱的总重量，该圆柱的总重量通过与谷物的摩擦相互作用而部分地由侧壁支撑。这被称为詹森效应。通过组合的实验和数值研究，在这里我们证明了反向的詹森效应，其中，由底座支撑的重量部分克服了这一作用。我们表征了此现象对所涉及的各种控制参数的依赖性，合理化了导致异常现象的压缩摩擦力出现的物理过程，并引入了一个模型来再现我们的发现。与先前的假设相反，我们的结果表明，材料元素上的本构关系可以取决于所施加的应力。