摘要
落石冲击垫层的动态冲击力与冲击深度是棚洞结构设计的重要依据。级配作为垫层颗粒粒度分布的重要特征,决定了垫层各级粒径颗粒的分配情况,影响了落石冲击垫层的动态过程。为研究颗粒级配对落石冲击垫层动态响应的影响,采用离散元-有限差分耦合方法,其中离散元模拟颗粒垫层,有限差分法模拟棚洞混凝土结构。在垫层平均粒径相等的情况下,开展了落石冲击不同级配垫层的动力响应数值模拟研究,通过对落石冲击力、顶板中心压应力、落石冲击深度的分析,揭示了落石冲击颗粒垫层的动态响应机制。研究结果表明:颗粒间力链的稳定性决定了垫层受冲击后的动态响应特征;颗粒间的摩擦是冲击能量耗散的主要方式,耗能占比达70%~80%;对于单峰型级配,单峰对应的粒径越小,力链长度越长,稳定性越差。峰值粒径d_(t)=75 mm时的峰值冲击力为d_(t)=25 mm的1.9倍,顶板峰值压应力为其3.6倍;对于双峰型级配,双峰的距离越近,颗粒周围约束的数量越少,力链的稳定性越差。非均质系数H_(e)=0.65时的峰值冲击力比H_(e)=0.33时的大40%,顶板峰值压应力大30%,粒径分布的离散性决定垫层受冲击后的响应特征。
The dynamic response characteristic of rockfall impact cushion is the key basis of rock-shed design.As an important feature of cushion particle size distribution,gradation determines the distribution of particle size and affects the dynamic process of rockfall impact cushion.To study the influence of particle gradation on the dynamic response of rockfall impact cushion,the numerical simulation of the dynamic response of cushion with different gradations is carried out by using a discrete element-finite difference coupling algorithm.Under the condition that the average particle size is equal,through the analysis of impact force,central compressive stress,and impacd_(t)epth of falling rock,the dynamic response mechanism of rockfall impact particle cushion is revealed.The results show that:the stability of the force chain between particles determines the dynamic response characteristics of the cushion after impact.The friction between particles is the main way of energy consumption,accounting for 70%-80%of the energy consumption.For single-peak grading,the smaller the particle size of the single peak is,the longer the force chain length is,and the weaker the stability is.When the peak particle size d_(t)=75 mm,the peak impact force is 1.9 times that of d_(t)=25 mm,and the peak compressive stress is 3.6 times.For bimodal gradation,the closer the distance between the two peaks is,the less the number of constraints around the particles is,and the worse the stability of the force chain is.When the heterogeneity coefficient H_(e)=0.65,the peak impact force is 40%larger than that when H_(e)=0.33,and the peak compressive stress is 30%larger.The uniformity of particle distribution determines the response characteristics of the cushion after impact.
作者
黄福有
张路青
周剑
曾庆利
HUANG Fuyou;ZHANG Luqing;ZHOU Jian;ZENG Qingli(Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education,Beijing University of Technology,Beijing 100124,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2023年第2期413-428,共16页
Chinese Journal of Rock Mechanics and Engineering
基金
国家重点研发计划项目(2019YFC1509703)
第二次青藏高原综合科学考察研究资助项目(2019QZKK0904)
中国科学院重点部署项目(KFZD-SW430)。
关键词
岩石力学
级配
离散元-有限差分耦合
缓冲垫层
动态响应
rock mechanics
gradation
discrete element-finite difference coupling
cushion layer
dynamic response
