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A technique for the in-mass measurement of the horizontal to vertical pressure ratio and thedetailsofthe experimental apparatusare presented.Adevicewas built for simultaneous measurements of three normal stresses within agranular medium. Byrecording thetiltofthisdevice itwas possible to determine one vertical and two horizontal stress components, which provided two independent values of the pressure ratio. A series of tests was conducted on wheat and barley in a model bin under both virgin and repeated loading. The pressure ratio was monitored throughout theduration of thetests. Density changes and friction forces in the bin were measured by an Instron testing ma chine and a load cell placed below the false bottom. The results showed that the pressure ratio remains constant with increasing overburden pressure for the initial loading, however, it increases with subsequent loading cycles. There seems to be a correlation between the pressure ratio and the stiffness ofthe granular material. Experimentally determined values ofpressure ratio of0.38 for barley and 0.48 for wheat were reasonablyclose to the value of 0.4 recom mended for all grains by the Canadian Farm Building Code. The deformation of the granular material was mostly nonrecoverable upon unloading. The walls ofthe cylindrical test bin with aheight to diameter ratio of 3 carried about 60% of the vertical surcharge loading.
G.J. Law, S.C. Negi and J.C. Jofriet 1993. A METHOD FOR MEASUREMENT OF HORIZONTAL TO VERTICAL PRESSURE RATIOS OF WHEAT AND BARLEY IN A CIRCULAR BIN. Canadian Agricultural Engineering 35(1):45-49.
Canadian Society for Bioengineering