| Grain,as a common granular material,not only presents the general mechanical properties of granular material,but also because grain is a kind of vital active material with breathing function,and the related requirements of its storage quality.Therefore,the granular material has different mechanical properties from the general granular material.Grain is an important strategic material,most of which is stored in granary in the form of granular materials.Grain bulk in granary produces lateral pressure on the granary wall and vertical pressure on the bottom of grain pile.the former is an important mechanical parameter of granary structure design,which has been studied more and more mature.While little research has been done on that lat.However,because grain bulk is different from common rock and soil mass,special sensors are needed for the bottom pressure test of grain pile,so it is necessary to develop special pressure sensors for grain pile environment and carry out the field real warehouse test research on the bottom pressure of grain pile.On the basis of the previous research of relevant personnel,with the support of the public welfare scientific research project of grain industry(No.: 201413303-4),the actual environment of granary and grain pile is fully investigated,the stress characteristics of grain pile bottom are analyzed,the structure design and trial production of the special pressure sensor for grain pile are carried out,the indoor performance test of the sensor is carried out,and the sensor performance calibration of grain pile granular medium environment is carried out,so as to improve and perfect the manufacturing scheme of the sensor,and lay the foundation for the real warehouse test.On this basis,this paper closely combined with the relevant research has been carried out on-site test and simulation analysis of grain reactor bottom pressure test,carried out the pilot test and real warehouse field test,according to the actual warehouse size,design the sensor layout scheme and signal testing and receiving scheme,on-site measurement of two warehouses.Through the test of a certain period of time,the data of the pressure at the bottom of the grain pile in different space and time are obtained,and the distribution law of the pressure at the bottom of the grain pile at any time is analyzed and obtained.The distribution and variation of the bottom pressure of grain pile were obtained by testing the bottom pressure of large bulk grain silo under pilot test and actual working conditions.The pressure distribution at the bottom of grain pile will be affected by grain density,feeding mode,cage on the interior of the silo,wall friction and other factors during the static stacking process.Through the comparative analysis of the data,it is found that the pressure value is smaller than the standard value at the initial stage of grain pile formation,and the pressure distribution at the bottom of grain pile varies greatly,and the pressure value at each measuring point is closely related to the grain feeding process.With the passage of time,the pressure value of each measuring point at the bottom of the overall trend of increasing,but the increase of the overall pressure gradually tends to be stable,the pressure value gap gradually becomes smaller,the pressure value gradually approaches to the standard value.After a certain period of field experiments and tests,the sensitivity and long-term stability of the sensor can meet the requirements,which is suitable for the environmental pressure test of grain piles.The research in this paper enriches the experimental research content of granular materials,especially grain granular materials,lays a foundation for further research on grain pile pressure field,and provides a reference for the design of storage structure and the research in related fields. |
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