土石混合料剪切力学特性的精细化离散元分析  

The Shear Mechanical Characteristics of Soil-rock Mixture Using a Refined Discrete Element Method

作　　者：涂义亮 李军 方忠 周成涛[4] 张立舟[4] TU Yiliang;LI Jun;FANG Zhong;ZHOU Chengtao;ZHANG Lizhou(State Key Laboratory of Mountain Bridge and Tunnel Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Xiaogan Urban and Rural Planning and Architectural Design Institute Co.Ltd,Xiaogan,Hubei 432100,China;China Construction(Shenzhen)Design International Co.Ltd,Shenzhen,Guangdong 518057,China;Chongqing Survey Institute,Chongqing 401121,China)

机构地区：[1]重庆交通大学省部共建山区桥梁及隧道工程国家重点实验室,重庆400074 [2]孝感市城乡规划建筑设计院有限责任公司,湖北432100 [3]悉地国际设计顾问(深圳)有限公司,深圳518057 [4]重庆市勘测院,重庆401121

出　　处：《铁道工程学报》2024年第9期22-29,共8页Journal of Railway Engineering Society

基　　金：中国博士后科学基金项目(2020M673110);重庆市技术创新与应用发展专项面上项目(CSTB2022TIAD-GPX0046,CSTB2024TIAD-GPX0051);重庆市建设科技计划项目(城科字2024第2-7号)。

摘　　要：研究目的:土石混合料具有非均质、非均匀、非连续、显著的结构效应等特点,其物理力学性质十分复杂。为探究含石量对土石混合料剪切力学特性的影响,本文基于真实块石形状,提出了块石逆向重构的数字图像法,建立了土石混合料离散元数值模型,并在此基础上开展了6种含石量试样在4种不同法向应力下的三维离散元直剪试验。研究结论:(1)剪应力-剪切位移曲线主要经历弹性阶段、初始屈服阶段、峰值强度阶段、残余强度阶段四个阶段;(2)在剪切过程中,块石转动存在明显的“齿轮带动效应”,土颗粒运动具有明显的“绕石”现象,颗粒的运动呈明显的漩涡状;(3)力链主要沿着剪切力和法向力的夹角方向分布,随着含石量的增大,力链偏向水平剪切方向的角度越大;(4)剪切面演化主要经历微裂隙阶段、剪切面贯通阶段、剪切带扩宽阶段,剪切带宽度随含石量增加而增加,且逐渐向逆时针方向偏转;(5)土石混合料抗剪强度随含石量的增大而增大,通过拟合发现,黏聚力和内摩擦角均与含石量呈指数函数关系;(6)本研究成果可为土石混合料相关工程设计和施工中的力学参数取值提供参考。Research purposes:Soil-rock mixture(SRM)is characterized by heterogeneity,nonuniformity,discontinuity and remarkable structural effect,and its physical and mechanical properties are very complex.In order to explore the influence of rock block proportion on the shear properties of soil-rock mixture,a discrete element numerical model of soil rock mixture was established based on the real shape of rock blocks and the reverse reconstruction of rock block using digital image method.On this basis,the three-dimensional discrete element direct shear tests of six rock contents samples under four different normal stresses were carried out.Research conclusions:(1)The shear stress-shear displacement curves can be divided into four phases including elastic, initial yield,peak strength and residual strength.(2)In the process of shearing,the rotation of block stones has obvious "gear driving effect",the movement of soil particles has an obvious "rock around" phenomenon,and the movement of particles has an obvious vortex shape.(3)The force chain is mainly distributed along the angle between shear force and normal force. With the increase of rock content,the angle of the force chain towards the horizontal shear direction increases. (4)The evolution of shear plane mainly goes through micro crack stage,shear plane penetration stage,and shear band widening stage. The width of shear band increases with the increase of rock content, and gradually deflects counterclockwise.(5)The shear strength of soil-rock mixture increases with the increase of rock content. Through the fitting formula,the cohesion and internal friction angle are exponential functions with the rock content. (6)The research results can provide reference for the determination of mechanical parameters in the design and construction of SRM engineerings.

关 键 词：土石混合料 剪切特性 真实块石形状 直剪试验 离散元 

分 类 号：TU43[建筑科学—岩土工程]