Finite Element Analysis Of Dynamic And Static Lateral Pressure Of Stored Material In Reinforced Concrete Silo

In the recent years, as the rapid development of cement industry, clinker silo which is the most important structure of cement plant has been used more and more widely. But in the meantime, some new problems come follow it. For one thing, after a period of time of use, repeated filling and discharge would lead to severe wear on reinforced concrete silo wall. For another, rupture and collapse of silo happened both at home and abroad. The occurrences of these problems are closely related to stored material lateral pressure.Stored material belongs to granular media. The interaction among stored material particles and the surrounding medium are complex, being very difficult to formulate a complete and accurate theoretical description of this problem; therefor one of the most important problems for a silo designer is the accurate prediction of the wall pressures induced by the stored material. At present, silo codes of14main countries in the world are based on the modified Janssen formula. The result of static lateral pressure calculated by Janssen formula agree well with the true value and reflect forced state of silos when stored material are static. However, it does not provide methods for the calculation of dynamic lateral pressure, so dynamic lateral pressure was simplified as the product of static lateral pressure and overpressure coefficient by codes of different countries, which cannot reflect the actual forced state of silos during discharge. Whether the calculation of the lateral pressure, especially the dynamic lateral pressure during discharge is right or wrong is directly related to the safety, reliability and rational economy of silo and therefore it is necessary to carry out a further research on static and dynamic lateral pressure induced by the stored material.A large number of related literatures are studied and the development course of study of stored material lateral pressure is reviewed. Based on practical engineering, a further research on the distribution and variation of static and dynamic lateral pressure induced by the stored material is carried out. The main research contents and results are as follows:(1)Three dimension finite element models of deep silo of bottom discharge and shallow silo of side discharge are built by large finite element analysis software ABAQUS, where Drucker-Prager criterion is employed to describe the constitutive behavior of stored material, the interaction between the stored material and the silo walls is modeled with friction contact surfaces and large displacements of stored material are taken into account. Static and dynamic lateral pressures induced by the stored material are simulated. Then the parameter analysis was presented considering the diameter of silo, the Poisson ration, internal friction angle, friction coefficient and density of stored material.(2)The results obtained from FEM simulation are compared with the pressure estimations established by different standards like the Chinese GB50077-2003, the American ACI313-97and R313-97and the German DIN1055and provide evidence for the improvement of code.(3)Wear test of silo is carried out and the simplified formula for calculating wear of reinforced concrete silo is obtained. Then, based on the results of finite element analysis and different working conditions, wear condition of silo walls are analyzed, which provide evidence for silo design and reinforcement.