Study On Mechanical Behavior Of Invert Tapered Shell Bottom Board Structure For Large-diameter Reinforced Concrete Underground Silo

In order to research and develop new system of underground storage, study of national"twelfth five-year" plan for science&technology support program——“Research anddemonstration on key technologies of the energy-saving and green grain storage” areresearched by the team of our school. This thesis is a part of the project, studies on stressmechanism for underground silo.In order to change the existing storage mode, and make full use of the currentlyunderground storage, the new underground granaries which include large-diameter cylinder,side tube and semi-cylinder are proposed by the team of the project. Many experts point outthat the underground granary large-diameter cylinder is better than others.Large-diameter reinforced concrete underground silo is made of the roof adoptedbeam-slab structure, wall adopted cylinder shape structure with constant section and bottomboard adopted invert conical shell structure with central support. Among them, the stress ofbottom board structure is more complex and no corresponding calculation method in actualdesign. The primary researches of the thesis are invert tapered shell bottom board structure’sstress and deformation, the most adverse conditions and the laws of stress and deformation inthe first load condition (lateral pressure of the surrounding soil and the pressure of the uppersoil etc.) and the second load condition (wall pressure and the pressure of the upper soil etc.).Based on the basic theory of soil-structure interaction and load analysis, the paper findsthat groundwater has been the control load; The large-diameter reinforced concreteunderground silo is taken as research object, respectively using the theory of conical shellsand finite element program (MIDAS) method for the analysis of the internal force of thebottom section of the value under different conditions. the first load condition is the mostunfavorable by the comparison and analysis of the internal force under different conditions.Then the paper studies and identifies the mechanical calculation model of invert tapered shellbottom board structure by comparing the analysis results of the two calculation methods.45degrees is the most favorable by the comparative analysis of stress for bottom board structurein the same diameter(25m) under different slope angle (25°,30°,35°,45°) gradient. And theforce analysis on the structure with different diameters(25m,30m,35m,40m) in the mostfavourable slope angle (45°), shows that with the increase of the diameter, internal forcebottom board section increases, especially near the outer edge of the moment9m range increase too fast, and analysis by strengthening scheme of large-diameter bottom boardstructure. Finally, the study of bottom board structure influential factors with the method oforthogonal design, finds that the diameter variation is the main factors that influence theinternal force of the structure, the secondary factor is the slope angle, almost no influence ofintermediate support section size.