不同卸料流态对仓壁侧压力影响的试验研究

Experimental Study on Influence of Material Density on Discharge Flow in Silo

为了观察筒仓卸料过程中内部流态及其相对应的仓壁压力变化进行研究,现基于物理模型试验,自主设计并制作半圆形筒仓,采用压实和松散两种装料方式,观察卸料过程中不同的物料流态.结果表明,当采用压实装料时,物料表现为管状流,采用松散装料时,物料表现为整体流与漏斗流共存.通过自主设计定制的土压力盒传感器来测定贮料及卸料工况下仓壁压力数值,将仓壁压力数值与物料流态联合分析,结果显示:在贮料工况下,压实装料时仓壁压力数值与Janssen公式计算值具有较好的一致性,松散装料时,内部力链网络疏松,仓壁压力数值较大.在卸料工况下,物料流态为管状流和漏斗流时,仓壁压力变化稳定,物料流态为整体流时,仓壁压力具有较大的波动性变化.对两种不同装料方式下,仓壁压力进行超压分析,发现物料表现为管状流和漏斗流时,无较大的超压变化,物料表现为整体流时,有较大的超压现象,最大超压系数为1.85,且仓壁压力波动性最大点与超压现象最大点一致.在筒仓卸料过程中,不同的装料方式具有不同的流态,同时,仓壁具有不同的压力变化规律,该研究可为构建和完善筒仓结构安全设计提供参考.

In order to observe the internal flow state and the corresponding wall pressure change during the unloading process of the silo,based on the physical model test,the semi-circular silo was designed and manufactured independently,and the two types of compaction and loose charging were adopted.Different material flow patterns during the unloading process were studied.The results indicated that when the compaction charge was used,the material exhibited a tubular flow state.When the loose charge was used,the material exhibited a coexistence of the overall flow and the funnel flow.Through the self-designed customized earth pressure box sensor,the pressure value of the wall under the storage and discharge conditions was determined.The pressure value of the wall and the material flow state were combined and analyzed.The results indicated that under the storage conditions,when the loading was compacted,the pressure value of the wall was in good agreement with the calculated value of the Janssen formula.When the material was loosely loaded,the internal force chain network was loose and the pressure of the wall was large.Under the unloading condition,when the material flow state was tubular flow and funnel flow,the wall pressure changed stably,and when the material flow state was the whole flow,the wall pressure had a large fluctuation change.Under the two charging modes,the overpressure analysis of the wall pressure of the silo wall showed that there was no large overpressure change when the material was expressed as a tubular flow and a funnel flow.When the material was in the overall flow,there was a large overpressure phenomenon.The maximum overpressure coefficient was 1.85,and the maximum point of wall pressure fluctuation was consistent with the maximum point of overpressure phenomenon.In the silo unloading process,different charging methods had different flow patterns.At the same time,the silo wall had different pressure variation rules.This study could provide references for constructing and perfecting the silo structure safety design.