网格状带齿加筋体界面特性的宏细观力学机制研究

网格状带齿加筋是一种新型的土工加筋技术，汲取了传统网格状与条带式带齿加筋的优点，其筋土界面特性是加筋结构设计的基础。利用室内拉拔试验从宏观角度分析筋材与土的界面特性，结合颗粒流程序，筋材用平行黏结模拟，从细观角度分析筋土接触界面的产生和发展演化规律。数值结果表明：齿筋的存在对界面处颗粒的移动及剪切带的宽度影响显著，其破坏模式呈现波浪型，在齿筋附近出现应力集中现象。筋土界面处筋材与土颗粒摩擦、咬合和阻抗作用提供“似黏聚力”是改变网格状带齿加筋体系作用机制的内在原因。研究成果对于明确网格状带齿加筋拉拔的机制及模型的建立都具有意义。

Micro and meso-mechanism study of interface behavior of earth reinforced with denti-inclusions

Sandy soil reinforced with denti-inclusions is a new concept of reinforced soil. In the grid with denti-inclusions, besides the conventional latticed inclusions, vertical reinforced elements are also placed in the soil. The behavior of interface between soil and geosynthetics is a significant factor for analysis and design of reinforced earth structures which is simplified as pullout performance. This paper presents the results of pullout tests and numerical simulation aimed at studying the interaction mechanism of reinforced sand. The pullout test is carried out to study the macroscopic mechanism. PFC is adopted to simulate pullout tests and the interface between geosynthetics and sand with emphasis on the meso-analysis. On such a basis, the model of PFC is established by using parallel-bond model to simulate the reinforcement. The sand particle movement trajectory and the particle contact orientations are studied. The results show that the shear bond is influenced by the denti-inclusions and the stress concentration occurs nearby the denti-inclusions. The intrinsic factors which form and change the mechanism of the interface properties are the “cohesion” provided by friction, occlusive force and passive resistances. The study results can provide a new understanding for future studies on the mechanism of the reinforced interface.