Experimental Study And Simulation By PFC On Bottom Pressure Of Bulk Grain Storehouse Under Different Operating Modes

Grain storehouse is the major type of storehouse in domestic grain deposits. Its storage scaleaccounts for85percentages of national total sum of grains. However, national grain depositsmainly depend on labors to conduct checking work for a long time. This way is backward ontechnique and costs too much. Besides, some lawbreakers make use of the shortcoming ofsupervision and regulation to resell national grain, seriously impacting its safety. Based on thepressure sensor technique, developing a set of real-time monitoring system for the grainstorehouse can replace the traditional checking method and realize real-time and efficientsupervision so that the supervisory level of grain sector will be enhanced and the safety ofnational grains will be guaranteed.Under different operating modes, the distribution of grain pile’s bottom pressure is thetheoretical basis of the above system. The related researches did in the past mainly focusedon silo’s dynamic lateral pressure and flow pattern. While macro mechanics of continuummedia bening used to analyze the granular materials, and their discrete and moving featureoften confilcts wiht the hypothesis of uniform and continuum. The existing research results isunable to provide sufficient supports for developing such an system. Therefore, filedexperiments combined with numerical analysis are adopted to conduct researches on thebottom pressure of bulk grain storehouse.Five field experiments were successively performed on test storehouses located in Henanand Shandong province, studying the mechanical performance of vibrating cord pressuresensors when applied in grain pile, studying the factors of grain pile’s bottom such as heightand friction, studying the impact of unloading locally on the bottom force field of the wholegrain pile. The relation between grain pile’s bottom pressure and its height was mainlyresearched. Besides, the situation of home-made pressure sensors used to test the bottompressure of the grain pile was introduced. Based on the field experiments, PFC3D(particleflow code in three dimensions) was used to build numerical models of field experiments. Thelocal grain storehouse and the whole grain storehouse under ideal loading process weremodeled and analyzed, the granular flow caused by the gravity from single door and double doors on the same side were modeled and analyzed as well. MATLAB was used to plot thetendency chart of the distribution of bottom pressure in three dimensions.The in-suit results reveal that the grain pile’s bottom is impacted by its height, friction,formation mode, piling time and other factors. Under ideal loading process, the relationbetween grain pile’s bottom pressure for a single point and its height is approximately linear,but the overall distribution of bottom pressure is non-uniform. To a grain storehouse which isfull of grains, its bottom pressure is dynamic during the piling process; and the local grainpile tends to be self-balancing and its bottom pressure will not be effected by the localunloading from other part. The simulation results obtained by PFC are coincident with themajor experimental results, which versifies the properties of grain pile’s bottom. Besides,compared with the calculation achieved by related code, the bottom pressure’s value ofsimulation is much smaller. The research results provide theoretical basis for developing areal-time monitoring system. It also can provide references to related researches in the fieldof mechanics of granular media.