土-海底沉管隧道体系三维地震响应分析

以港珠澳大桥工程中大型海底沉管隧道为工程背景,根据工程场地土层地质实际分布情况,建立了沉管隧道上方无回淤土和有回淤土两种计算条件下的土-沉管隧道体系的大型三维精细化有限元计算模型.在计算模型中考虑了沉管接头非线性、土与隧道间的接触非线性和土层介质非线性等特征.采取直接从基岩面输入一致地震和地震行波两种激励方式,运用动力显式算法对土-沉管隧道体系进行地震响应分析.数值结果表明,回淤土体减小了模型的自振频率,增大了隧道的地震响应;不同地震波激励形式和激励方向对隧道接头的相对变形和管节内力响应的影响不容忽视.

Three-dimensional Seismic Response Analysis of Soil-undersea Immersed Tunnel System

According to the large-scale undersea immersed tunnel of the Hong Kong-Zhuhai-Macao Bridge, and based on the actual site soil geological distribution, three-dimensional refinement FEM models were built considering the siltation above the tunnel with and without siltation. The nonlinear characteristic of flexible joints, the nonlinear contact effect between the soil and tunnel, and the nonlinear behaviour of soil material were all taken into account in the calculation model. With uniform excitation and travelling wave excitation input directly on the bedrock surface, the earthquake response analysis of soil-immersed tunnel was conducted with the dynamic explicit algorithm. Numerical results have shown that the existing siltation soil above the tunnel reduces the natural frequency of soil-immersed tunnel system and increases the seismic response of tunnel. The excitation mode and excitation direction of seismic wave also have certain influence on the relative deformation of flexible joints and the internal force response of tunnel, which can not be ignored.