Experimental Study On Static And Dynamic Characteristics Of Wheat Steel Silo Wall Interface

Food is one of the most important materials for the people.Food security is the material basis for social stability and people’s happiness.With the increase of grain production year by year,grain turnover has become more frequent.Ensuring the safety of grain in the turnover link is the key factor to ensure the food security.Steel silo is widely used in the field of grain turnover because of its lower construction cost and short construction period.The interaction between grain and steel silo wall is one of the important factors affecting the stability of silo structure.In this paper,wheat,one of the main crops in China,is selected as the storage material in the warehouse to obtain the static and dynamic characteristics of the interface between wheat and steel warehouse wall.A series of monotonic shear tests,cyclic shear tests and post cyclic single shear tests were carried out to investigate the static and dynamic characteristics of wheat steel interface under different influence factors.The main contents and conclusions of this paper are as follows:(1)The monotonic shear test of wheat steel interface was carried out by using the improved grain direct shear apparatus,and the static characteristics of wheat under different void ratio,vertical pressure and preloading conditions were studied.The results show that:under the same void ratio,the higher the vertical pressure and the smaller the void ratio of wheat,the higher the peak strength and residual shear strength of wheat steel interface,and the more obvious the softening phenomenon of shear stress shear displacement curve.The final shear shrinkage increases with the increase of vertical pressure and decreases with the decrease of void ratio.The peak shear stress of wheat steel interface increases and the shear shrinkage decreases with preloading.(2)The cyclic shear test of wheat steel interface was designed and carried out.In the process of cyclic shear,the shear stress of wheat steel interface presents a shear hardening phenomenon,which increases with the increase of vertical pressure and decreases with the increase of void ratio.With the increase of cyclic shear times,the peak shear stress of each circle increases gradually;The dynamic shear modulus increases with the number of cycles,and the growth rate decreases gradually;The change of damping ratio is opposite to the dynamic shear modulus.The damping ratio decreases with the increase of vertical pressure and increases with the increase of void ratio at the same number of cycles.The damping ratio of wheat steel interface first decreases and then tends to be stable with the development of the number of cycles;The dynamic shear modulus and damping ratio increase with preloading.(3)The single shear test of wheat steel interface after cyclic loading was carried out.The results show that the shear stress development law of wheat steel interface is similar to that of monotonic shear test,but the shear stress corresponding to the same shear displacement is larger than that of monotonic shear test,and the corresponding strength is also improved.After 10 cycles of cyclic shear,the wheat steel interface tends to expand first and then shrink under different conditions.The test can provide reference for interface static and dynamic shear test,and the test results can provide basic test parameters for the design of steel silo,which is of great significance to improve the safety of steel silo structure design.