Experimental Study on Wall-Normal Pressure and Overpressure Coefficient in Silos with Different Height-to-Diameter Ratios

当前针对筒仓卸料过程中超压现象的研究中，受限于实验测量手段或模拟假设条件，尚缺乏对不同高径比条件下超压分布规律的系统实验验证。为此，本文针对现有实验方法的不足，设计了一种改进的筒仓内壁法向应力测量系统，搭建半圆锥形筒仓模型，测量粒径为1.29 mm的玻璃珠在静态堆积和卸料过程中的壁面法向应力，并计算卸料过程中最大动态应力与静态应力的比值(即超压系数)。实验设置了不同填充高度，分别代表浅仓与深仓工况，系统分析了卸料过程中超压系数的时空分布特征。结果表明：静态阶段颗粒发生沉降与重排，使应力逐渐趋于稳定；卸料阶段动态应力显著增加，并在H = 135 mm处达到峰值。不同填充高度下，最大超压系数位置略有差异，但均集中于圆柱形中下部，最大值达到3.31。漏斗段尤其靠近卸料口区域的超压现象相对较弱。本研究揭示了高径比对筒仓内壁应力与超压分布的影响，为筒仓结构设计与卸料安全提供了可靠实验依据。Current studies on overpressure phenomena during silo discharge are often limited by experimental constraints or simplified simulation assumptions, and lack systematic experimental validation under varying height-to-diameter (H/D) ratios. To address this gap, an improved wall normal pressure measurement system was developed in this study. A semi-conical silo model was constructed to measure the wall normal stress of 1.29 mm glass beads during static packing and discharge. The overpressure coefficient—defined as the ratio of the maximum dynamic pressure during discharge to the corresponding static pressure—was calculated. The experiments were conducted at different filling heights, representing both shallow and deep silo conditions, to analyze the spatiotemporal distribution of overpressure coefficients. Results show that during the static phase, particle rearrangement and settling lead to pressure stabilization; in the discharge phase, dynamic pressure significantly increases and reaches its peak at H = 135 mm. Although the position of the maximum overpressure coefficient varies slightly with filling height, it consistently appears in the mid-lower region of the cylindrical section, with a maximum value of 3.31. In contrast, the overpressure effect is notably weaker in the hopper section, especially near the outlet. This study reveals the influence of height-to-diameter ratio on the wall pressure and overpressure distribution in silos and provides reliable experimental evidence for structural design and safe discharge operations.