浅埋矩形顶管背土效应形成及演化机理研究

浅埋矩形顶管背土效应导致顶进力骤增，引起周围土体变形加剧，严重威胁顶管及周边环境安全。如何探明其施工过程中“管道—背土—周围土体”相互作用机制，系统揭示背土效应的诱因、驱动力及演化发展过程，是矩形顶管领域亟需解决的科学问题。本课题旨在通过理论分析、管土接触面直剪试验、室内矩形顶管模型试验和数值模拟等方法，研究不同因素对矩形顶管周围土体扰动效应和破坏机理的影响规律，分析不同条件下管土接触界面力学特性，探明背土效应的诱发机理和驱动摩阻力形成机理，揭示背土形成和演化过程中的力学机制、临界破坏条件及发展模式，最后在建立矩形顶管管道土压力、摩阻力和土体扰动理论模型的基础上，结合实际工程监测数据，构建不同工况条件下浅埋矩形顶管背土效应预测力学模型。研究成果不仅对矩形顶管工程的设计和施工具有重要指导意义，也可为浅埋矩形顶管技术突破长距离、大断面的限制提供科学依据。

The carrying-soil effect of shallow buried rectangular pipe jacking results in the sudden increase of jacking force, which leads to the intensification of soil deformation and threatens the safety of pipe jacking and surrounding environment seriously. It is an urgent scientific problem in the field of rectangular pipe jacking that how to investigate the interaction mechanism of "pipe-carrying soil-surrounding soil" in the construction process and reveal the inducement, driving force and evolutionary process of carrying-soil effect. By means of theoretical analysis, direct shear test of pipe-soil contact surface, rectangular pipe jacking model tests and numerical simulation, this project aims to research the influence of different factors on soil disturbance effect and failure mechanism around the rectangular pipe jacking. With analyzing the mechanical properties of pipe-soil contact interface under different conditions, the mechanisms of carrying-soil induction and driving frictional resistance are ascertained. Simultaneously, it reveals the mechanical mechanism, critical failure condition and development mode of carrying-soil in formation and evolution process. Finally, based on the theoretical models of pipe soil pressure, frictional resistance and soil disturbance of rectangular pipe jacking, a mechanical model for predicting carrying-soil effect of shallow buried rectangular pipe jacking under different conditions is constructed combining with actual engineering monitoring data. Therefore this research achievements not only have an important guide for the design and construction of rectangular pipe jacking projects, but also provide a scientific basis for shallow buried rectangular pipe jacking technology to break through the limitation of long distance and large section.