基于阻尼器反力墙体系的特大型LNG储罐控制研究

特大型液化天然气（LNG）储罐的固有频率通常介于2~10 Hz之间,处于大部分地震运动的频率范围之内。在过去的几十年中,许多事故已经证明,储罐在地震作用下很容易遭破坏。使用隔震支座来减少储罐的地震作用已经被证明是非常有效的,但对于特大型LNG储罐,其连接组件对隔震层层间位移有严格限制,尤其是在软土场地中,桩水平抗力与隔震层位移是一对矛盾,普通隔震系统会在隔震层产生较大位移,导致特大型LNG储罐连接组件的设计非常困难。因此提出了一种由环形阻尼器反力墙、粘滞阻尼器以及安装于基桩顶端的隔震支座组成的新型隔震系统,反力墙独立设置于地基中,不与桩基连接,罐底的部分剪力直接向反力墙传递。以容量为16万m3的特大型LNG储罐为例,建立多自由度集中质量简化模型,以层间位移、桩基剪力作为性能指标进行了评价分析。结果显示,新型隔震系统对特大型LNG储罐隔震层位移及桩基剪力的控制非常有效。

Study on Seismic Control of Large-scale LNG Storage Tank Based on Damper Reaction Wall Isolation System

Most of the large liguified natural gas（LNG） tanks have a fundamental frequency between 2 and 10 Hz which involves range of resonant frequency of most earthquake ground motions.In the past few decades,many accidents happening in earthquakes proved that the tanks could be damaged easily by earthquakes.It is an effective way to reduce the response of storage tank by use of isolation system in strong earthquake.However,there is a strict restriction of connection component on interlayer displacement of isolation system for large LNG storage tank.It is a contradiction between horizontal resistance of piles and isolation layer displacement.The displacement of the isolation system used in large LNG storage tank under earthquakes is always very large especially in soft site,which means that the design of connection components is relatively difficult.Hence,a new isolation system composed of damper reaction wall,viscous dampers and isolators mounted on top of pile is presented in this paper.The damper reaction wall which is not connected with the piles is embedded into the ground independently so that the part of shear force of tank bottom is directly transferred in the damper reaction wall.A practical large LNG tank using new isolation system which can contain 160000 m3 LNG was analyzed by the multi-degree-of-freedom lumped mass model.The efficiency of the isolation system was investigated by analyzing several parameters such as isolation layer displacement,pile shear and so on.The results show that new isolation system is very effective to control the isolation layer displacement and pile shear.