筒仓内壁静态与动态法向应力的测量与分析
Measurement and Analysis of Static and Dynamic Normal Pressure on Silo Walls

精准测量满载和卸料时颗粒物质对筒仓内壁的法向应力，掌握应力随时间和高度的变化规律，与筒仓的安全运行密切相关。本文设计了一种基于全桥电路的电阻应变式传感器，通过搭建筒仓应力测量系统，采用均值粒径为1.29 mm的透明玻璃珠进行实验，测量筒仓静态堆积和卸料过程中的壁面法向应力。静态应力的测量结果表明，颗粒填充完成后，在圆柱形部分出现了静态应力随着高度的降低而减小的区域，这与Janssen模型不一致。然后我们分析了每一个检测点在卸料过程中动态应力最大值的时空分布，结果表明，动态应力最大值出现在圆柱形中下部分，而不是筒仓几何转变处。最后我们计算了最大动态应力与静态应力的比值，得到了每个检测点的超压系数，发现超压系数最大值出现在H = 215 mm处。该研究对筒仓结构设计具有重要意义，有助于对应力增幅显著的区域进行结构优化，为提高筒仓的安全性和耐久性提供了关键参考。
Accurately measuring the normal pressure exerted by granular materials on the inner walls of silos during loading and unloading, and understanding the variation of pressure over time and height, is closely related to the safe operation of silos. This study designed a resistive strain gauge sensor based on a full-bridge circuit and constructed a silo pressure measurement system. Experiments were conducted using transparent glass beads with an average particle size of 1.29 mm to measure the normal pressure on the silo walls during static filling and unloading processes. The results of static pressure measurements showed that, after filling, a region in the cylindrical section exhibited a decrease in static pressure with decreasing height, which is inconsistent with the predictions of the Janssen model. Subsequently, we analyzed the spatiotemporal distribution of the maximum dynamic pressure at each measurement point during unloading. The results showed that the maximum dynamic pressure occurred in the lower-middle part of the cylindrical section rather than at the geometric transition of the silo. Finally, we calculated the ratio of the maximum dynamic pressure to the static pressure at each measurement point to obtain the overpressure coefficient, and found that the maximum overpressure coefficient appeared at H = 215 mm. This study is of great significance to the structural design of silos, as it helps optimize the structure in regions with significant pressure amplification during unloading, providing key references for improving the safety and durability of silo operations.