Nonlinear FEM Analysis Of Preloading Spiral Case Based On Simulation

The characteristic of preloading spiral case is that the surrounding concrete is constructing as keeping a certain pressure in the steel liner. Then remove the preloading pressure which inflict on the steel liner as the surrounding concrete has all been coagulation, so slit will be formed between the steel spiral case and the surrounding concrete because of the contraction of the steel liner .We can make the structure's stress to be more reasonable through using different preloading water head, Therefore the preloading spiral case has obtained a widespread application in the actual project.In former research, a lot of suppositions have been used when carried on FEM analysis of preloading spiral case, so the result is not very precise. Focused on this question, a 3D-noliner simulation model has been established to simulate the construction and running process of the preloading spiral case in this paper. The following aspects are studied:(1)Using the simplification method, a 3-D non-linear finite element analysis has been carried on to analyze the preloading spiral case, the stress distribution of the rebar, the range and the processes of damage in surrounding concrete are obtained.(2)Considering the real construction and running process of the preloading spiral case, a 3D-noliner simulation model has been established .The entire process including preloading loads, construct the surrounding concrete as keeping a preloading pressure, removing the preloading load, then inflicting the complete load. The slit between steel spiral case and surrounding concrete has been studied in this paper. The stress distribution of the steel liner and rebar, the range and the process of damage in surrounding concrete are obtained. The primary cause to the difference between the results of these two kinds method has also been discussed.(3)Based on the selected rebar ratio, a 2-D non-linear finite element analysis has been carried on with different preloading water head to study the relationship between the stress distribution of steel liner, the reinforced concrete and the preloading water head, and the influence of preloading water head on the range of damage in surrounding concrete was also been analyzed.During the modeling and calculating, the simulation of structure is as accurate as possible to reflect the characteristic of real engineering. As a result, some useful conclusions are drawn and can be referred to the real project.