摘要
为准确表征出高铁级配碎石填料的压实过程,采用新型智能振动压实仪,分别从物理力学层面表征出级配碎石的压实过程。提出改进Viola-Jones算法量化出振动压实过程中级配碎石颗粒粒径、颗粒形状的演化规律,最后通过离散元方法揭示了振动压实中的颗粒破碎对级配碎石宏细观力学性能的影响机制。研究结果表明:在振动压实试验中,级配碎石的干密度在振动压实过程中不断增大,而力学性能Kb却出现了“软化”的现象;级配碎石在振动压实前后级配没有明显变化,内部粗颗粒细长比变化也不明显,而圆度在压实后逐渐增加,表明级配碎石在振动压实过程中的颗粒破碎模式并非为颗粒被压碎,而是颗粒边缘突出、薄弱部位被分化、磨圆,可采用圆度来量化振动压实过程中颗粒破碎程度(研磨度);试样强度随着研磨度的增加而逐渐减小,且呈现出三阶段演化机制:0.1≤DF≤0.4时,试样强度损失较小;0.4<DF<0.7时,试样强度出现明显损失;0.7≤DF≤1.0时,试样强度没有明显损失。并通过颗粒平均配位数、滑动与转动等细观指标进一步揭示了振动压实中的颗粒研磨度对试样强度影响机制。研究成果可进一步揭示高铁级配碎石振动压实机理,也可为高铁路基智能压实控制技术奠定理论基础。
In order to accurately characterize the compaction process of graded gravel fill for high-speed railway,a new intelligent vibration compaction instrument was used to quantity the properties of graded gravel fill from the physical mechanical aspects during the vibration compaction process.Moreover,the improved Viola-Jones algorithm was proposed to quantify the evolution of particle size and shape of the graded gravel fill during the vibration compaction.Finally,the influence mechanism of the particle crushing on the macro-micro mechanical properties of graded gravel fill during the vibration compaction was revealed by the discrete element method.The results show that in the vibration compaction tests,the dry density of graded gravel fill increases with the increase of vibration time,while the mechanical property Kb“softens”with the increase of vibration time.The graded gravel fill has no obvious change in gradation before and after vibration compaction.The slenderness ratio of the internal coarse particles has no obvious change,while the roundness increases gradually after compaction.This phenomenon indicates that the particle crushing mode of graded gravel fill in vibration compaction is not that the particles are crushed seriously,but that the particles are differentiated and rounded at the prominent and weak parts of the particle edges.The roundness can be used to quantify the particle crushing degree(friction degree)during compaction.The strength of the sample decreases gradually with the increase of the degree of grinding,and presents a three-stage evolution mechanism.When 0.1≤DF≤0.4,the strength loss of the sample is small.when 0.4<DF<0.7,the strength loss of the sample is obvious.When 0.7≤DF≤1.0,the strength loss of the sample is not obvious.The average coordination number,sliding and rotation further reveal the influence mechanism of particle crushing on the strength of the sample during the vibration compaction.The research results can further reveal the vibration compaction mechanism of grade
作者
谢康
陈晓斌
尧俊凯
王业顺
邓志兴
XIE Kang;CHEN Xiaobin;YAO Junkai;WANG Yeshun;DENG Zhixing(School of Civil Engineering,Central South University,Changsha 410075,China;Railway Engineering Research Institute,China Academy of Railway Sciences Co.,Ltd.,Beijing 100081,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2023年第9期3217-3228,共12页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(51978674)
中国铁道科学研究院集团重点课题(2020YJ143)
中国铁路设计集团重点课题(2020YY240606)
中南大学中央高校基本科研业务费专项资金资助项目(2022ZZTS0622)。
关键词
高铁路基
振动压实
颗粒破碎
形状演化
力学特性
离散元法
high-speed railway foundation
vibration compaction
particle crushing
shape evolution
mechanical properties
discrete element method
