Study On Temperature And Pressure Coupling Of Steel Silo-Grain Pile System Under Quasi-Static Storage Conditions

Steel silo is a kind of bulk material storage structure with high storage efficiency,wide application range and green environment protection,which is composed by thin-walled shell structure and support structure.With the wide application of silo in industry and agriculture,the capacity of silo is increasing.And during the use of steel silo,the engineering accident of destabilization and damage of steel silo caused by temperature and pressure effect happens from time to time.The complex pressure field in large silo will lead to the change of thermal conductivity of grain pile(solid-gas two-phase material)and the change of temperature field,and the change of temperature field will produce the temperature stress effect on the structure.The change of temperature inside the silo is likely to cause damage such as mold and insects in the silo,and the temperature stress will lead to structural damage.Therefore,it is important to study the temperature-pressure coupling problem of grain pile for grain storage safety as well as silo structure safety.In this paper,through a combination of experiments and numerical simulations,the thermal conductivity characteristics of the grain pile affected by pressure and moisture content are studied,a finite element numerical model considering the coupling effect of pressure and temperature inside the silo is established,and the effect law of temperature action on the pressure of the silo wall is further explored.The specific research includes:(1)Based on the Fourier heat transfer theory,a home-made pressure-thermal conductivity characteristics test device was developed.The thermal conductivity characteristics of bulk materials such as wheat,japonica rice,rapeseed and standard sand under the influence of overlying pressure and moisture content were studied by transient hot line method,and the pressure-thermal conductivity characteristics model of bulk materials was established.(2)The relationship between the porosity of bulk material and pressure and water content was derived by compression test.The numerical model of the thermal conductivity of the bulk material was established using a combination of PFC and COMSOL,and the thermal conductivity characteristics under the action of porosity and particle morphology were investigated.And the numerical simulation results are compared with the experimental results.(3)The proposed pressure-thermal conductivity characteristics model is applied to numerical simulations and a model of the lateral pressure on the silo wall considering the effect of temperature is established.According to the established finite element numerical model,the effect of the lateral pressure on the silo wall of silos with different height-to-diameter ratios by uniform temperature change and the effect of the temperature field caused by solar radiation on the stress of the silo wall are analyzed.And the lateral pressure theory is compared and verified with the European code and the silo code in China.