穿越变化地层的沉管隧道接头地震响应的解析解

Analytical solution of seismic response of flexible joint of immersed tunnel crossing different strata

沉管隧道接头是穿越变化地层的沉管隧道抗震设计的关键。介绍了穿越变化地层的沉管隧道接头地震响应的理论分析模型。分析模型包含两个柔性接头和3个管节单元,利用Pasternak双参数地基模型模拟下卧地层,利用Euler-Bernoulli梁模型模拟沉管隧道管节,考虑了穿越变化地层的沉管隧道接头的力和变形传递,立足于两端连接人工岛的沉管隧道类型,以自由边界模拟结构两端连接方式。基于矩阵传递原理,建立了考虑行波效应的沉管隧道接头的地震响应解析解。利用有限元模拟结果验证了解析解的可靠性。发现使用柔性接头可以明显减小变化地层界面的剪力和弯矩,自由边界条件下,接头剪切刚度主要影响接头剪力,接头弯曲刚度主要影响接头弯矩。当沉管隧道接头的受力呈现同向最大值时,对应的地震波相位角并不一致。地震波垂直入射时,接头受力最小。

Flexible joint is a key factor in the seismic design of the immersed tunnel when crossing through variable strata.This paper presents a theoretical model of the seismic response of flexible joint of immersed tunnel through different strata.The analytical model consists of two flexible joints and three tube elements.The Pasternak two-parameter foundation model was used to simulate the subsoil,while the Euler-Bernoulli beam model was used to simulate the immersed tunnel.The force and deformation transmission conditions of the joint in the immersed tunnel crossing through variable strata were considered.The analysis was based on the type of immersed tunnel that connects the artificial island at both ends,and free end boundary conditions were used to simulate the connection at both ends of the tunnel.By applying the matrix transfer principle,an analytical solution was to assess the seismic response of joints in immersed tunnels,accounting for the traveling wave effect.Verification of the analysis scheme was performed using finite element simulation results,demonstrating that flexible joints can effectively reduce shear forces and bending moments at strata interfaces.Under free end boundary conditions,joint shear stiffness mainly affects the joint shear force,and joint bending stiffness mainly affects the joint bending moment.The phase angles of seismic waves differ when forces reach the maximum values.When seismic waves are vertically incident,joint experiences the minimal force.