高速铁路斜坡软弱地基路堤非埋式桩板结构动力服役性能演变行为及机制研究

Sloped weak ground has special causes and engineering properties, using the pile plank structure can effectively control the deformation of the embankment, but the dynamic interaction mechanism between the embankment over sloped weak ground and pile plank structure under the train loads is still not clear. Based on a large scale dynamic model test, through the synergy of multiple actuator, implementing the high-speed movement of multiple train wheel, recreating the behavior of macrokinetics of the embankment-pile plank structure over sloped weak ground; Adopting the 3-D discrete-continuous dynamic coupling field method, simulating the dynamic interactions between spherical particles and grid unit in the interface of soil and structure, developing a connector between the softwares of Particle Flow Code in 3 Dimensions and Fast Lagrangian Analysis of Continua in 3 Dimensions; Considering the difference between the rigid and compacted pile plank structure, and flexible and loosening soil, creating a dynamic simulation model of embankment-pile plank structure over sloped weak ground effected by the train loads; developing the sensitivity analysis of design parameter such as pile foundation, bearing plate, embankment, foundation, etc, exploring the macro damaged failure morphology and mesoscopic gradually variational catastrophe process; obtaining the dynamic interaction mechanism between the train loads and embankment-pile plank structure over sloped weak ground, constructing its design index system, and then proposing some effective measures to improve the structure. Results could provide a new and creative thought for the dynamic interactions of soil and structure, meanwhile, complementing and perfecting the design theory of high-speed railway embankment-pile plank structure over sloped weak ground.

斜坡软弱地基具有独特的成因及工程特性，采用桩板结构可有效控制路堤沉降变形，但斜坡软弱地基路堤-桩板结构受列车荷载的动力相互作用机制尚不清楚。基于大比例动力模型试验，通过多个作动器协同作用，实现多个列车轮对高速移动，再现斜坡软弱地基路堤非埋式桩板结构的宏观动力学性态；采用三维离散-连续动力耦合场方法，模拟土-结构交界面处球状颗粒与网格单元动态相互作用，研发颗粒离散体PFC3D程序和有限差分连续体FLAC3D程序接口；考虑桩板结构刚性密实状与土体柔性松散状的差异，创建斜坡软弱地基路堤桩板结构受列车荷载作用的全动态仿真模型；开展桩基、承载板等设计参数敏感性分析，探究宏观损毁破坏形态及细观渐近灾变过程；获得斜坡软弱地基路堤-桩板结构列车荷载动力相互作用机制，构建其设计指标体系，提出有效结构改进措施。成果可为土-结构动力相互作用提供一种全新思路，补充和完善高速铁路斜坡软弱地基路堤桩板结构设计理论。

斜坡软弱地基具有独特的成因及工程特性，采用桩板结构可有效控制路堤沉降变形，但斜坡软弱地基路堤-桩板结构受列车荷载的动力相互作用机制尚不清楚。该项目结合国内公路、铁路、岩土等行业规范，从成因、分布、工程特性等方面入手，较系统地比较了”斜坡软土”与一般“软土”的异同，明确了“斜坡软土”的概念，并尝试提出了“斜坡软土”相应的判别标准；开展了斜坡软弱地基路堤的概率稳定性分析、降雨条件下瞬态稳定性分析、基于颗粒流的稳定性分析、拉裂缝对稳定性影响分析；基于有限元宏观模拟、颗粒流细观仿真，引入地基变形系数，阐释了路堤荷载作用下斜坡软弱地基的变形耦合机制，并获得离心模型试验成果的验证；构建了兼顾“变形”与“稳定”的斜坡软弱地基路堤双指标设计体系；编制了基于半解析有限单元法高速交通荷载作用下路基路面结构力学行为快速分析计算程序、可利用高速移动荷载作用下实测动态弯沉开展结构层模量反算的程序；揭示了板底脱空地段、土基回弹模量易衰变地区、高寒地区的路基路面车致损伤规律，并进行了长期性能预测；明确了碎石桩+抗滑桩、系梁式桩网结构、防滑铲等工程对策的处治效果及其机理；形成了斜坡软弱地基路堤处治措施合理选择、板下土体脱空科学判识与防治方面相对完善的工程对策体系。该项目已发表期刊论文14篇（其中SCI检索源刊1篇、EI检索源刊8篇）、录用待发表期刊论文2篇（其中EI检索源刊2篇），培养毕业博士2名、硕士7名。研究成果可科学指导西部山区高速铁路斜坡软弱地基路堤桩板结构设计改进与优化。