Finite Element Study On The Pressure Of The Side Wall Of The Large Diameter Concrete Shallow Barrel Under Eccentric Discharge

With the rapid development of industry of our country in recent years, cement clinker which is the important structure of cement plant has been constructed and used more and more extensively. In the meantime, scholars have begun to pay more attention to silo structure. Currently, the research of concrete silo mainly focused on central discharge while the study of eccentric discharge is relatively less, however, the existing theoretical models of the eccentric discharge entirely adopted the slender silo thus it cannot accurately describe the distribution of the silo lateral pressure in eccentric discharge which will bring security risks to the silo structure. This paper analysed the squat silo under eccentric discharge with the finite element numerical simulation and the theoretical study of the lateral pressure on the wall, which based on the National Natural Science Foundation "Research on Dynamic Action Mechanism and Design Method of the Wall in Large-diameter Concrete Squat Silos under Eccentric Discharge".The major work in the thesis is described as follows:1. In order to study the characteristic of wall stress and lateral pressure in the squat silo under eccentric discharge, the analysis is been carried out according to two different forms of the squat silo with the slab foundation and ring beam foundation. The finite element procedure ABAQUS is been used to establish a contact analysis on eleven different silo and stored solids models, then the the correctness of the FEM by reduced scale silo experiment is verified.2. The results of the squat silo with slab foundation show that the values of lateral and vertical pressure at all points of silo wall are constantly decreasing, the circumferentially axial tension is also reducing. The maximum value of lateral pressure occurs at the full state. The hoop stress and the vertical bending moment reached the most disadvantage state under an intermediate state of eccentric discharge. The maximum circumferential stress is 20%-50% larger than that at the full state when the eccentricity is greater than 0.35. The maximum ratio of the vertical bending moment is relatively small when the eccentricity is less than 0.3, The maximum ratio is 1.71 when the eccentricity is greater than or equal to 0.3.3. The results of the squat silo with ring beam foundation show that the maximum value at each point of the wall lateral pressure is increases firstly and then decreases with the discharge, the maximum value of the lateral pressure at the initial stage of the discharge is greater than that at the full state, and the maximum lateral pressure is at the bottom of the wall. The maximum ratio of circumferential stress increases with the increasement of eccentricity, and the maximum value is 1.44. The moment of the squat silo with ring beam foundation is been almost released, so both of the circumferential moment and the vertical moment are very small.4. As for the research on the calculation method of lateral pressure of squat silo under eccentric discharge, we analyse the silo specifications of China, Europe and Australia and summarize the results of various parametric analyses, then the application scope together with the advantages and disadvantages are discussed. Finally we propose the ring and vertical calculation formula of squat silo under eccentric discharge both for the slab and ring beam foundation after obtaining the variation of the circumferential stress and the vertical bending moment through summarizing the comparative analysis results of the ratio of height to diameter, eccentricity and constraint condition.