基于透明土技术的格栅加筋路堤破坏机理宏细观研究

In order to improve the stability and integrity of the embankment on soft soil, reinforcement is performed by using geogrid due to its excellent mechanical properties. However, the existing theory and design method ignore the influence of foundation deformation and geogrid stress distribution, so they can’t fully consider the effect of the grid reinforcement on the soft soil. The failure mechanism is still far from clear. Due to the lack of effective measurement methods, most studies are limited to macro rules summary and influencing factors. The purpose of this research is to investigate macro-micromechanics of slip surface development and failure mechanism of geogrid-reinforced embankment on soft soil using pullout tests and modeling tests by transparent soil experimental technique, in combination of coupling discontinuum-continuum numerical simulation. Global, continuous, and fine measurement measurement of internal deformation and geogrid tension is based on the laser speckle technique and Particle Image Velocimetry (PIV) technology. Measurement of particle movement in the sliding zone is based on the digital visual tracking technology. Accordingly, considering the influence of foundation deformation and geogrid stress distribution, the computation methods of stability of geogrid-reinforced embankment based on micromechanics are expected to be presented. There will be profound theoretical significance and socioeconomic performance of this research results for the application and development of transparent soil experimental technique, and the design and construction of geogrid-reinforced embankment on soft soil.

土工格栅因其优良的力学性能而常被用作软土地基上路堤的加筋材料，以提高路堤的稳定性和整体性。现有的分析方法不考虑筋材应力分布和地基变形对稳定性的影响，难以充分评估筋材对路堤稳定性的提高作用，也无法对加筋破坏机理做深入分析。因受制于量测手段，研究成果多限于宏观规律总结和影响因素分析。本课题拟采用基于透明土技术的拉拔摩擦试验和模型试验，利用激光散斑技术和粒子图像测速技术对土体内部变形、格栅拉力进行全局、连续、精细化测量，利用数码可视化追踪技术测量滑动带土颗粒运动规律，并结合离散-连续耦合数值模拟，研究软土地基上格栅加筋路堤滑移面的宏细观演化规律及其破坏机理。在此基础上，考虑地基变形与筋材应力分布，建立基于细观力学的稳定性计算方法。研究成果对软土地基上格栅加筋路堤的设计和施工具有重要的基础理论意义和显著的社会经济效益，并有助于推动透明土试验技术在工程中的应用和发展。

土工格栅因其优良的力学性能而常被用作路堤的加筋材料，以提高路堤的稳定性和整体性。现有的分析方法不考虑筋材应力分布和地基变形对稳定性的影响，难以充分评估筋材对路堤稳定性的提高作用，也无法对加筋破坏机理做深入分析。因受制于量测手段，研究成果多限于宏观规律总结和影响因素分析。本课题采用基于透明土技术的拉拔摩擦试验和模型试验，利用激光散斑技术和粒子图像测速技术对土体内部变形、格栅应变进行全局、连续、精细化测量，并结合数值模拟和理论分析，研究格栅加筋路堤破坏机理。归纳起来的主要研究内容和成果如下：基于透光率提出了透明土透明度定量评估方法，并系统研究了透光率与厚度、温度、粒径和压力的定量关系；自主研发了一套“基于透明土技术的立体可视化拉拔摩擦试验机”，实现了加筋土的精细化、全过程、立体量测；通过大型可视化土工格栅拉拔试验，揭示了加筋土剪切带的细观演化规律和筋土荷载传递机制；通过加筋地基模型试验，揭示了条形基础荷载下加筋地基内部位移场演化规律和筋材作用机理，并推导了加筋地基承载力公式；提出了考虑地基变形与筋材应力分布的稳定性计算方法。研究成果有助于透明土技术的应用推广，对加筋土工程的设计和施工具有重要的基础理论意义和显著的社会经济效益。