Research Of Seismic Response And Soft Ground Treatment Of Oil Tanks

Oil tanks store up combustible and explosive liquid medium. Tank destruction under theeffects of earthquake or dehiscence of the tank bottom produced by large amount of unevensettlement, is likely to lead to disastrous economic losses and devastating secondary disasters.Thus tank seismic response and settlement in soft soil foundation are two main research topicsthe large-scale development of storage tank after in tank development towards large-scale.Based on the large finite element analysis software ADINA, the wholetank-liquid-ground simulated models of vertical cylindrical unanchored tank are founded,considering the foundation-tank interaction and the coupling interaction between storage tankand internal liquid. Seismic responses in tanks of different volume are analysed, providingbasis to tank seismic design. Based on the partial conclusion of analysis of tank seismicresponse, tanks of different volume are divided into three components: large volume, mediumvolume, small volume. Numerical simulations are made to three foundation treatmentmethods(water filling preloading method of small tank, compounding foundation of cementpowdered jet piles of medium tank, precast pile foundation of large tank) with FLAC3Dgeotechnical engineering software. Studies on the properties of deformation and foundationsettlement of these three foundation treatment methods are made, which have certain directivesignificance to the actual engineering. Work in this paper is:1, Summations of tank seismic research theories and test results, and every settlementcomputation theories and settlement calculation methods of these three kinds of groundtreatment are made in the first chapter.2, In the second chapter, on the basic of dynamic response characteristics of tanks in earthquake, Summaries of basic equations of tank seismic response and fluid motion, andfinite element equations of tank-liquid system are made. Analysis mode choosed in thefoundation settlement simulated models and allowable values of tank foundation deformationare also introduced. Chapter2lays the theoretic foundation for the next numerical analyses.3, Considering the foundation-tank interaction and the coupling interaction betweenstorage tank and internal liquid, models of eight tanks of d ifferent volume with differentliquid storing height with ADINA are made, then analyses of liquid sloshing wave height,stress and peak acceleration of rigid wall of these models are made in chapter3.4, Vertical displacement time-history analyses and stress analyes of tank bottom nodeand the corresponding node of liquid are made. Based on the analyses, chapter4summarizesthe size effect to tank bottom, and validates the lift-off mechanism of tank bottom.5, This paper illustrated the tank-foundation-Dynamic-Interaction, analysed tankcharacteristics under the uneven settlement, and draw a conclusion that suitable methodsshould be chosen to reduce the tank uneven settlement.6, Loading rate has a direct effect on the treatment of water filling preload ing method.Studies on the influence of loading rate on tank foundation settlement and side displacementof deep foundation with FLAC3D are shown. Summaries of the relationship between loadingrate and formation and abreaction of excess pore water pressure are made. The numericalsimulation of loading path among tanks in reasonable spacing is carried out to seek the rightloading path.7, In view of compounding foundation of cement powdered jet piles, influences of pilelength, pile spacing, pile stiffness on additional stress, settlement, lamination settlement andside displacement of tank foundation are studied with FLAC3D in chapter6.8, Models of precast pile foundation with single pile, four piles, nine piles are createdunder the condition of one-time loading and stage loading with FLAC3D. Analyses of theeffect of pile groups, pile group settlement of different amounts and pile-soil relativedisplacement are shown.Research results may provide basic theory support and value validation for tank Anti-seism design and soft soil foundation treatment and have certain directive significance inengineering practice.