考虑多尺度的富水软土地层地铁隧道群长期运营沉降预测方法

Many in-situ measurements on metro tunnels show a significant effect of tunnel group on the settlement of tunnels during their service life in saturated soft soils. Current analyses of settlement focus on a single tunnel. This project aims to investigate the physical and mechanical mechanisms of tunnel group effect and to suggest an elaborate modelling method for the long-term settlement of metro tunnel group in soft soils. The project focuses on typical load characteristics during service of tunnels, and the multi-scale characteristics of tunnels-soil interaction. Some key issues are studied: (1) the characteristics and distribution of typical combinations of cyclic loading are clarified; (2) based on the micro-macro multi-scale characteristics of soft soil, a micromechanics based multi-scale model considering the effect of large numbers of cyclic loading and creep is established; (3) on the basis of the multi-time scale characteristic of traffic loading, and enhancing the time homogenization method, a material and time multi-scale coupling model for efficiently simulating large numbers of cyclic loading is proposed; (4) based on the multi-scale spatial characteristics of tunnels-soil interaction problem, adopting both the finite element and meshless methods, incorporating the material and time multi-scale coupling model, a multi-scale modelling approach for tunnels-soft soil interaction is developed. All results of this project provide theoretic support for controlled deformation techniques of tunnels in soft soil sites, which has important scientific significance and application value.

大量地铁隧道的现场实测表明，富水软土地层中地铁运营过程引起的隧道沉降具有显著的隧道群效应，现有研究大多针对单一隧道进行运营沉降分析。申请项目旨在查明隧道群效应的物理机制及微观机理，建立软土地层地铁隧道群长期运营沉降的精细化预测方法。项目针对隧道群的复杂荷载特征以及多尺度特征，开展如下关键研究内容：（1）明确隧道群运营条件下典型循环荷载组合特征及分布规律；（2）从软土的微观结构多尺度的本质出发，提出考虑超大数目交通循环荷载及蠕变效应的软土材料多尺度本构模型；（3）针对循环加载的时间多尺度特征，改进时间均质化方法，提出能高效模拟超大数目循环加载的材料与时间多尺度模型；（4）根据隧道群问题的空间多尺度特性，进行有限元法-无网格法耦合方法的二次开发，形成隧道群-软土相互作用多尺度模拟方法。本课题研究成果为软土地区隧道群变形控制技术提供理论支撑，具有重要的科学意义和广泛的应用价值。

软土中地铁隧道有多尺度的特征和显著的隧道群效应。为此，本课题进行了以下几个方面的研究：开展了大量的隧道群以及地下空间群调查，开展了软土宏微观试验，开展了多尺度模拟；进行了模型程序开发，进行了基于优化方法的智能参数标定，编制了本构模型的程序；建立了有限元法-无网格法耦合方法的二次开发，以及本构模型的有限元二次开发，比奥固结理论耦合本构模型的程序，有限差分-离散元耦合计算二次开发；分析了隧道渐进破坏过程，完成了隧道群运营条件下典型循环荷载组合特征及分布规律。通过本项目的研究，截止结题时，已发表 SCI 收录论文 51 篇， EI 收录论文 6篇；申请发明专利 2 项；出版专著 3 本。该项目中所提出的多尺度计算平台可以准确预测软黏土地基-多隧道相互作用，以及长期变形与渐进破坏的复杂性，弥补了传统的试验技术与经典的计算方法诸多的不足，从而推动了软土地下工程变形控制技术的发展。