隧道工程复杂多体接触系统的非线性数值模拟方法及相互作用研究

Nonlinear contact is a common phenomenon in tunnel projects. Contact problems generally lead to discontinuous deformation and probable stress concentration in local regions, playing a critical role in safety control. With the rapid construction of infrastructure in China, the interaction between tunnels and their adjacent structures has become increasingly widespread. The interaction involves numerous multi-body systems. To evaluate it from an engineering point of view, requirement for large-scale numerical simulations is arising..To fulfill these demands, this research aims to develop the contact parallel computing technique for tunnel engineering. This work are facing yet unsolved challenges from nonlinear numerical contact algorithms, especially combined with high performance computing. To deal with the resultant multi-disciplinary issue, we introduce the new achievements in computational mechanics, computational mathematics and computer science to the specific engineering field. Then, a series of improvements are proposed to make the scientific computing methods applicable for complex engineering projects..By collecting the improved algorithms, a numerical scheme is presented to simulate the multi-body contact system in tunnel engineering. A high performance computing software is developed to efficiently operate supercomputer system. This software is then applied to perform large-scale parallel simulations for practical projects. Based on the numerical results, the nonlinear contact effect is analyzed for the coupled interacting system, which composed of tunnels and adjacent structures. This research is envisioned to provide a new tool for engineering applications.

非线性接触问题广泛存在于隧道工程中，其导致的不连续变形现象和应力集中效应，可能成为安全性控制的关键环节。同时，随着我国基础建设的快速发展，隧道与邻近结构之间的相互作用日益成为工程安全评价中亟待解决的关键技术问题之一，而大规模数值模拟是一个有效工具。.为此，本项目面向隧道工程接触大规模并行计算的迫切需求，针对非线性接触算法及高性能计算方面的挑战，引入计算力学、计算数学、计算机科学等多学科交叉领域内的新成果，重点研究解决从接触并行基础算法跨越到大型工程应用所面临的困难。.在此基础上，发展一套可适用于实际隧道工程中复杂多体接触系统的高效非线性数值算法，自主研发具有高可扩展性的大规模并行计算程序，为工程应用提供新的研究手段。在国产超级计算机上完成实际重大工程的大尺度区域精细化数值模拟成果，对隧道及周边结构所形成的相互耦合作用系统，评估接触问题对其力学特性的影响，为安全性控制提供必要的科学依据。

围绕隧道工程的安全性问题，面向复杂多体接触系统的基础理论及计算研究，从力学特性的综合分析出发，重点解决基础科学算法跨越到大型工程应用所面临的算法困难，发展了实用的大规模并行计算手段。面向浅埋海底隧道工程，提出波浪诱导海床瞬态液化的计算模型，统一了两种经典的液化判别准则。提出基于三场变分原理的对偶mortar有限元法，解决了常规mortar方法的约束交叉、主从偏见及求解效率等问题。提出渗流-应力耦合多体接触非线性算法，完成了千万自由度隐式求解。开展了混凝土软接缝的接缝挤压特性试验，提出了两种挤压特性模型。提出光滑粒子法（SPH）的mortar接触算法，实现大变形接触问题的精准模拟，突破了以往粒子类方法难以验证接触计算准确度的瓶颈。提出温度-应力耦合多体接触非线性算法，揭示了太阳热辐射温度应力所致混凝土结构破损机理。提出隧道衬砌背后空洞的过程演化模拟方法，揭示了闭合型空洞的隐蔽性和危害性。提出盾构隧道泥水劈裂的三维数值模拟方法，揭示了盾构隧道泥水劈裂形态、劈裂过程及其引起的地层位移变化规律。探讨了粗粒土应力加载与长期流变之间的相互耦合特性，揭示了流变变形的塑性硬化效应。

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