粗粒土与土工格栅接触面静动力变形和强度特性研究

Geogrid has been proved to be economical and easy to be carried out and is widely used to ensure the high rockfill dam’s safety in intense seismic area. But the reinforcement mechanics and applicative conditions have not been clearly understood. Particle image velocimetry (PIV) recognition technology and distributed fiber optic sensors are used in large direct shear apparatus. The impact on deformation and strength of the interaction between coarse-grained soil and geogrid is explored by geogrid arrangement, particle size and filling density. The influence on the dynamic characteristics of the interface is analyzed by loading properties. The static and dynamic deformation and strength characteristics of the interaction between coarse-grained soil and geogrid are investigated from macroscopic and microscopic perspective. The mechanism of geogrid reinforced coarse-grained soil is clarified. The elastoplastic model which is suitable for the interaction between coarse-grained soil and geogrid is established. The physical meaning of the model parameters is revealed. The method of determining parameters is proposed. On this basis, the geogrid reinforcement aseismic measures of high rockfill dams are deeply and systematically investigated. The theoretical reference is provided for design method of the geogrid reinforcement aseismic measures of high rockfill dams.

土工格栅加固措施具有经济性和便于施工等优势，近几年来为一些强震区高土石坝的设计方案所采用，但其抗震加固机理目前尚不清楚，难以进行合理设计。课题拟利用颗粒图像速度（particle image velocimetry，PIV）识别技术和分布式光纤传感器，采用大型直剪仪，探讨土工格栅排列方式、颗粒尺寸和填筑密度对粗粒土与土工格栅间的接触面变形和强度的影响；分析荷载特性对界面动力特性的影响。从宏观和细观上研究粗粒土与土工格栅接触面的静、动力变形和强度特性，阐明土工格栅加筋作用机理，建立适用于粗粒土与土工格栅的接触面弹塑性模型，揭示模型参数物理意义，建议参数确定方法。在此基础上，对高土石坝土工格栅抗震加固措施进行深入系统研究，为高土石坝土工格栅抗震加固设计方法提供理论参考。

土工格栅加固措施具有经济性和便于施工等优势，近几年来为一些强震区高土石坝的设计方案所采用，但堆石料与土工格栅等接触面的变形和强度特性试验研究不多。项目采用某在建的土石坝筑坝料为实验材料，采用大型直剪仪，研究了土工格栅排列方式等对粗粒土与土工格栅间的接触面变形和强度的影响，揭示了界面强度发挥机制，建立了基于广义塑性框架的接触面弹塑性模型。在此基础上，对高土石坝土工格栅抗震加固措施进行研究，综合评价土工格栅加筋后高土石坝的抗震性能。