Complete Process Analysis Of Concrete Outer Tank And Dome During The Construction Period Of LNG Tank

The energy structure is changing, due to the need of energy supply and reserves,thelarge prestressed liquefied natural gas (LNG) tank was built one after another in thedomestic. At present, we have’t master the design and construction technology of thisLNG tank yet. The amount of investment of LNG project is huge, if we achieved thedomestic independent design and construcion technology, that will bring great economicbenefit. In the existing domestic LNG tank construction project, the outer concrete tankwill crack during construction, at the same time in order to ensure the safety of theconcrete dome construction, a fine finite element model for a16000m3LNG tank wasestablished using the finite element software (ANSYS) to simulate the actualconstruction process. The specific research work are as follows:1. The temperature field under the load of heat of hydration is determined forchanging temperature conditions; The early thermal stress under temperature load isfigured out by the incremental method, considering the influence of concrete shrinkageand concrete creep; The tensile strength at early ages of concrete along withreinforcement ratio and time is identified. And the concrete crack distribution andprogress of LNG concrete tank is determined by comparing thermal stress with earlytensile strength. The results show that: the shrinkage of concrete has a significant effecton thermal stress, stresses in the simulation period of150days continue to show growthstate; The thermal stress of the first pouring section is greater than other casting section,there will have a large number of vertical crack and local circumferential crack on tankwall of the first pouring section.2. We discussed the inference of shuttering material、 construction quality、construction season and pouring temperature on cracks, and found that constructionquality and construction season have a strong inference on cracks. On this basis, thethermal stress is the combination of sigle effect of hydration heat、concrete shrinkage、environmental and casting temperature. Then, we proposed some suggestions onanti-cracking measures mainly by regulating the construction season, complementally byimproving the quality of construction.3. For the ribbed-type reticulated dome with steel plates of LNG tank, we putforward reasonable scheme for analyzing the stability during the construction stage. Thenonlinear load-deflection complete process analysis was carried out. And we discussedhow do the thickness of the steel plate, beam section size, rise to span ratio and initialgeometric imperfections affect the stability of the reticulated dome with steel plates. 4. According to various construction process of concrete dome, the analysis modelswere established respectively, and determined the air pressure of each constructionsegment. The safety factors of the reticulated dome were calculated under the appropriatepressure and initial geometric imperfections. And the ribbed-type reticulated dome withsteel plates was optimally designed.