循环直剪条件下粗粒土与结构接触面颗粒破碎研究

Particle breakage of gravel-structure interface under cyclic shear

循环剪切条件下粗粒土与结构接触面颗粒破碎规律的定量研究具有重要意义。循环剪切时,接触面产生了明显的颗粒破碎,并显著影响其宏观力学响应。接触面颗粒破碎细观上表现为大颗粒破碎、小颗粒含量增加及大孔隙的减少或消失,统计上表现为粒径分布曲线的抬升和特征粒径的减小,宏观上表现为接触面不可逆性剪切体变;且不可逆性剪切体变可作为接触面颗粒破碎等物态演化的宏观度量。接触面颗粒破碎主要由剪切引起,相对破碎率与剪切路程、不可逆性剪切体变与相对破碎率间的关系均可用双曲线描述。法向应力越大、结构面板越粗糙、硬度越小,接触面颗粒破碎和损伤越严重;且相对破碎率与法向应力间符合幂函数关系;剪切路径对接触面相对破碎率影响较小。

The particle breakage of gravel-structure interface is obviously observed during cyclic shearing, which significantly influences the mechanical response of the interface. The particle breakage mesoscopically leads to the increasing content of relatively small particles and the decrease and even disappearance of large void, statistically causes uplift of grain size distribution curve and reduction of grain size, and is exhibited and can be measured macroscopically by irreversible volumetric change of the interface. The relative breakage ratio of the interface mainly depends on and behaves in hyperbola manner with shear distance and is hardly influenced by shear path. The hyperbola model is also fit for the relationship between irreversible volumetric change and relative breakage ratio of the interface, and the relation between the relative breakage ratio and the normal stress obeys the power function. The type and roughness of the structural plate have effects on the relative breakage ratio of the interface.