考虑土结相互作用下核电厂海域沉管隧道三维抗震分析

Three Dimensional Seismic Analysis of Immersed Tunnel in Sea Area of Nuclear Power Plant Considering Soil Structure Interaction

为研究核电厂海域安全级取水沉管隧道的动力响应规律,综合考虑结构-土体的相互作用、复杂土体参数的非线性、沉管内部动水的对流效应和脉冲效应,建立了复杂土质地基条件下沉管-土体三维精细化有限元模型,并运用UPFs二次开发在ANSYS中创建了等价线性单元及黏弹性人工边界,在此基础上开展了极限地震作用下的沉管隧道动力时程分析。计算结果表明:层间位移角符合规范;顶板和底板以受弯为主,其中顶板3的弯矩最大,底板2的剪力最大;三个竖墙以受压为主。其中,中隔墙轴力最大;沉管隧道各墙连接部位内力较大,受地震影响最大。应提高顶底板的抗弯能力及竖墙的抗压能力,适当加固各墙连接部位,同时反应位移法、线弹性动力时程分析法、等价线性分析法三种方法计算出的内力规律基本一致,且等价线性法结果较为合理,反应位移法内力值较为保守。

In order to study the dynamic response law of safety level water intake immersed tunnel in the sea area of nuclear power plant,a three-dimensional refined finite element model of immersed pipe soil under complex soil foundation is established by comprehensively considering the infinite interaction between structure and foundation,the non-linear characteristics of complex soil,the convection effect and impulse effect of dynamic water in the immersed pipe.Using the secondary development of UPFs,the equivalent linear element and viscoelastic artificial boundary are created in ANSYS.On this basis,the dynamic time history analysis of immersed tunnel under limit earthquake is carried out.Results show that the maximum inter-story displacement angle of the middle partition wall under the two working conditions is less than the limit value of the code.The top plate and the bottom plate are mainly bent,in which the top plate 3 has the largest bending moment and the bottom plate 2 has the largest shear force.The three vertical walls are mainly compressed,and the axial force of the middle partition wall is the largest.Comprehensive analysis shows that the internal force at the connection part of each wall of the immersed tube tunnel is large,and it is most affected by the earthquake.The bending resistance of the top and bottom slab and the compression resistance of the vertical wall shall be improved,and the connecting parts of the walls shall be properly strengthened.At the same time,the internal force laws calculated by the three methods are basically the same,and the results of the equivalent linear method are more reasonable,and the internal force value of the response displacement method is more conservative.