基于离散元再生混凝土单轴拉伸细观数值研究  

Mesoscopic numerical atudy on recycled concrete under uniaxial tension based on discrete element model

作　　者：刘晶[1,2] 陈宣东 巩新枝 唐壮东 曾湧智 方梓婷 LIU Jing;CHEN Xuandong;GONG Xinzhi;TANG Zhuangdong;ZENG Yongzhi;FANG Ziting(College of Civil and Architecture Engineering,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory of New Energy and Building Energy Savig,Guilin 541004,China)

机构地区：[1]桂林理工大学土木与建筑工程学院,广西桂林541004 [2]广西建筑新能源与节能重点实验室,广西桂林541004

出　　处：《混凝土》2023年第4期45-50,共6页Concrete

基　　金：国家自然科学基金(52268002);广西科技计划资助项目(桂科AD21238025);2023年广西高校中青年科研基础能力提升项目(2023KY0269);广西建筑新能源与节能重点实验室开放基金(桂科能22-J-21-26)。

摘　　要：再生混凝土以其固废再利用的优势得到了广泛的关注,但不明确的破坏机理限制其工程应用。基于离散元理论,建立再生混凝土单轴拉伸细观离散元模型,模拟了再生混凝土单轴拉伸作用下裂纹发展及宏观力学响应,揭示了再生混凝土细观层面破坏机制。通过与现有的第三方试验对比,验证了所提出模型的可靠性。研究表明:初始裂纹的形成与扩展取决于新、老砂浆层的强度。当新砂浆强度大于老砂浆时,初始裂纹始于老界面;反之,初始裂纹主要始于新界面。进一步,老砂浆力学性能总体与再生混凝土抗拉强度、弹性模量正相关。但当老砂浆强度高于新砂浆强度后,随着老砂浆强度增长,再生混凝土强度基本不变。此外,清除附着的老砂浆可以有效的提升再生混凝土的力学性能;再生混凝土中再生骨料应来源于混凝土等级较高的构件。研究揭示了荷载作用下再生混凝土破坏机制,为再生混凝土的优化及在工程上运用提供了理论支撑。Because of the advantages of solid waste reuse,recycled concrete has been widely concerned,but its failure mechanism is not clear,which limits the application of recycled concrete in engineering.Based on discrete element theory,a uniaxial tensile mesoscopic model of recycled concrete was established to study the crack development and macroscopic mechanical response of recycled concrete under uniaxial tensile action,and the mesoscopic failure mechanism of recycled concrete was revealed.Compared with the existing third-party experiments,the reliability of the model is verified.The results show that the formation and propagation of initial cracks depend on the strength of new and old mortar.When the strength of the new mortar is greater than that of the old mortar,the initial crack begins at the old interface and extends to the old mortar and the new mortar successively.On the contrary,it starts from a new interface and extends to a new mortar.Furthermore,the mechanical properties of old mortar are positively correlated with the tensile strength and elastic modulus of recycled concrete.However,when the strength of old mortar is higher than that of new mortar,the strength of recycled concrete is basically unchanged as the strength of old mortar increases.In addition,removing the old mortar can improve the mechanical properties of recycled concrete,and the recycled aggregate should come from members with higher concrete grade.The research reveals the failure mechanism of recycled concrete under load and provides theoretical support for the optimization and application of recycled concrete in engineering.

关 键 词：再生混凝土 离散元 抗拉强度 老砂浆厚度 裂纹 

分 类 号：TU528.01[建筑科学—建筑技术科学]