| Oil storage tanks are extensively applicated containers in oil and petrochemical industries and related enterprises, they are quite important equipments for the crude oil reservation, oil refining, and oil-transferring. With the rapid development of the oil fields and petrochemical industry, the strategic position of energy reservation and distribution is constantly improved, compared with conventional storage tanks, large-scale tanks have many advantages, such as in favor of energy-saving investments, reducing the area of the land ,therefore, large-scale oil storage tanks have become an inevitable trend around the world.The large-scale tanks also bring about many new problems, on statical aspect such as increasing uneven foundation settlement, leading to distortion of bottom plate due to long-term use, increasing the probability of oil leakage due to bottom plate's corrosion and so on. In order to resolve these problems, many measures are raised, and the appearance of the new environment-friendly down tapered foundation is an important breakthrough, it is product of gravel ring wall foundation and environmental protection technology, it's outstanding feature is that the outer zone of the foundation is higher than the inner zone, so the bottom plate is like an down taper. However, the mechanical properties of this foundation are not completely understood by us. On dynamic aspect, there are also some problems, such as reduction of the tank stiffness, elongation of system period, change of the radio of height to diameter, which have a significant impact on the seismic performance of large-scale tank. Considering its storage of flammable, explosive media, the consequences are very serious in the event of earthquake disaster, and it is easy to produce secondary disasters such as fire disaster and environmental pollution, so an in-depth study of the static and dynamic properties of tanks is necessary.In this paper the mechanical properties and dynamic properties of 15×104m3 unanchored tank are studied with numerical simulation method, the main contents are as follows:(1)Static and dynamic research results of the storage tank are summed up, and the remaining problems are brought forward.(2) The theree dimensional finite element model of large storage tank is established with ADINA software using contact element, considering liquid-solid coupling and interaction between bottom plate and foundation, the states of stress of the tank wall, bottom plate and foundation are analyzed. (3)The impact of liquid height, foundation stiffness, the slope of foundation to stress of the tank and deformation of the bottom plate is analyzed; the simplified formulae to estimate the peak stress are put forward. In view of engineering application, the reasonable limits of the cone slope are analyzed, and the analysis of down tapered gravel foundation is also developed.(4)Using spring element to simulate the foundation, the natural frequencies and vibration modes of liquid-structure coupling vibration and liquid sloshing are analyzed, the effect of floating roof is also carried out, and the key system parameters which have great impact on two types of vibration are found out.(5)Four typical seismic waves (four sites) are selectde for three-dimensional seismic excitation, the seismic response of the tank is analyzed, and the results of the analysis are compared with those from well-known code formulae(6)The main researches of this paper are summarized and the further research that is closely related to this article is put forward.
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