Field Test And Discrete Element Simulation Of Vertical Pressure On The Bottom Of Warehouse

Grain is considered as the livelihood guarantee for the people.It is also a significant material for the national strategic reserve.China has a big capacity of grain storage.Thus,the safety and reliability of granary is the safety guarantee for the grain storage.The rectangular bin occupied a great deal of portion in China.The determination of grain pressure was important for the grain bin design and management,which also had a great practical significance.In the paper,the vertical floor pressure was obtained from a filed test.Based on the field test results,a discrete element model was also used to analyze the influence factors on the vertical floor pressure.The distribution of vertical floor pressure was observed by comparing the numerical simulation with test results.At the same time,the influence factors of vertical floor pressure were presented by the comparison.It included the particle shape,particle loading way and the friction coefficient corresponding with the bin wall.The description of vertical floor pressure was effectively supported by analyzing the interior and exterior influence factors.The main contents are as follows:(1)The basic characteristics of wheat samples were measured.The variations were analyzed including the specific gravity,bulk density and porosity.Under the effect of different water content,the friction coefficient was measured between wheat and other materials used in bin walls.The basic parameters are provided for the subsequent numerical simulation.(2)A rectangular field bin was instrumented by the vibrating string type pressure sensor,which analyzed the distribution of the vertical floor pressure along the whole bin.According to the field test data,the distribution of vertical floor pressure was investigated under different location with the variation of grain bulk height.Meanwhile,the vertical floor pressure of grain bulk was analyzed during the different storage time.(3)The wheat particles were simulated with ellipsoid particles.Also,the discrete element numerical model was established according to the filed test bin.The numerical model was verified through comparing the numerical simulation with the field tests results of the vertical pressure.The results showed that the ellipsoid particles established by PFC3 D,which can better simulate the vertical floor pressure of grain bulk during wheat packing process.A spatial distribution of the vertical floor pressure was consistent with the field test results.The vertical floor pressure in the middle of bin was greater than that near the bin wall.It is inconsistent with the uniform distribution recommended by the relevant codes.(4)Based on the field tests results,the influence on the vertical floor pressure was analyzed.The effects of particle shape,particle loading mode and friction coefficient were considered.It was affirmed that the shape of grain storage had an effect on the fluctuation of the pressure at the bottom of the bin.The particles were formed in different ways,which resulted in the compaction state of grain pile structure is also different.The vertical floor pressure of grain bulk was related to the friction coefficient and the distance along the bin wall.What's more,vertical floor pressure of grain bulk was most effectively affected by the friction coefficient along the bin wall.