矩形顶管隧道F型承插接头刚度模型与变形机制

The rectangular pipe jacking method has been used in subway stations, utility tunnel, underpass tunnel and other projects in recent years. The excessive longitudinal non-uniform deformation of the rectangular jacking tunnel with the F-type joints easily occurs due to the urban subway undercrosss, and it can lead to joint failure or even damage, affect the serviceability, endanger structural safety, and even cause engineering disasters. Therefore, with the increasing demand for urban subway undercrosss the rectangular pipe jacking tunnel, it is necessary and urgent to study the longitudinal deformation mechanism for this kind of tunnel. Therefore, the methods of structural segment joint test, three-dimensional numerical simulation, theoretical analysis and field monitoring data feedback etc. are used in this research. The models for internal force and deformation and stiffness of the tunnel’s F-type joint are established. The deformation mechanism along with the failure mode is studied, thus deformation control standards are built. The longitudinal deformation modes, distribution characteristic of dislocation and opening along the tunnel are explored. Based on the geological condition in Hohhot, Inner Mongolia, the prediction method of the longitudinal deformation model considering the weakened foundation coefficient and shearing effects is proposed. It is expected that the research results have important theoretical significance and engineering application value for the longitudinal design and operation safety of the Inner Mongolia Autonomous Region and China's rectangular pipe jacking tunnel.

近年来，矩形顶管法开始应用于地铁车站、综合管廊、下穿隧道等工程中。在城市地铁穿越扰动下，极易引起F型承插接头的矩形顶管隧道产生过度的纵向不均匀变形，导致接头失效甚至破坏，影响正常使用，危及结构安全，甚至引发工程灾害。因此，随着城市地铁下穿矩形顶管隧道的工程需求越来越多，针对该种隧道的纵向变形机制研究是必要而紧迫的。然而针对该种接头的刚度模型、变形机理及隧道纵向变形等理论问题尚不清楚。为此，本项目采用构件接头试验、三维数值模拟、理论分析及现场监测数据反馈等方法，建立F型承插接头的内力-变形关系模型及刚度模型；揭示F型承插接头的变形机理与失效模式，构建接头的变形控制标准；探索隧道的纵向变形模式、错台量与张开量的纵向分布特征；基于内蒙古呼和浩特地层条件，提出考虑剪切效应与纵向基床系数弱化的纵向变形预测方法。研究结果对于内蒙古及我国矩形顶管隧道的纵向设计与运营安全具有重要的理论意义与工程应用价值。

近年来，矩形顶管法开始应用于地铁车站、综合管廊、多车道隧道等工程中。外部扰动极易引起矩形顶管隧道F型承插接头失效甚至破坏，影响正常使用，危及结构安全，甚至引发工程灾害。因此，随着城市矩形顶管隧道的工程需求越来越多，针对该种隧道的纵向变形机制研究是必要而紧迫的。本项目以内蒙古包头市某矩形顶管行人过街通道为工程背景，采用室内构件试验、三维精细化数值模拟、理论解析等方法，获得了矩形顶管F型承插接头剪力-剪切位移以及弯矩-转角之间的关系以及刚度模型，采用纵向变形等效抗弯和抗剪原则，建立矩形顶管隧道的纵向等效抗弯和抗剪刚度，提出了等效抗弯刚度有效率η和等效抗剪刚度修正系数ξ，实现了对界限弯矩的分析；在此基础上，揭示了矩形顶管F型承插接头剪切和弯曲变形机制及破坏特征，分析了钢套环尺寸、断面形状等因素对接头刚度的影响规律，并提出了接头防水的变形控制标准，接头橡胶圈的压缩高度与接头防水性是否良好密切相关，当橡胶圈压缩高度与其自身高度之比介于0.286~0.500之间时，接头防水良好；构建了能够反应F型承插接头抗剪、抗弯性能三维壳接头模型，可模拟管节接头的转动、拉压和剪切力学特性，研究了多节管节的纵向变形机制、纵向变形模式以及错台量与张开量沿纵向分布特征，提出了纵向基床系数弱化条件下Winkler地基上的Timoshenko梁纵向变形预测方法，采用有限差分法，求得在支撑条件弱化的情况下矩形顶管隧道纵向变形解。将理论计算结果与数值模拟结果、现场监测数据进行对比验证。该成果助力包头市两座过街通道项目顺利贯通，应用前景广阔。对于内蒙古及我国矩形顶管隧道的纵向设计与运营安全具有重要的理论意义与工程应用价值。