冻融损伤混凝土单轴压缩细观破坏研究  

Research on meso failure of concrete subjected to freeze-thaw damage under uniaxial compression

作　　者：黄灵芝[1] 柯梅尉 司政[1] 杜晓奇 王正鑫 Huang Lingzhi;Ke Meiwei;Si Zheng;Du Xiaoqi;Wang Zhengxin(Institute of Water Resources and Hydro-electric Engineering,Xi’an University of Technology,710048,Xi’an,China;Lingshi County Electric Construction Engineering Co.Ltd.,031300,Lingshi,China)

机构地区：[1]西安理工大学水利水电学院,西安710048 [2]灵石县电建工程有限公司,灵石031300

出　　处：《应用力学学报》2021年第4期1400-1407,共8页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(51879217,51609200)。

摘　　要：根据冻融循环试验测得混凝土损伤层厚度,利用离散元软件建立冻融损伤混凝土数值模型;基于单轴压缩试验得到应力-应变曲线,标定不同冻融循环次数下混凝土中水泥砂浆间以及水泥砂浆与粗骨料薄弱接触面的细观参数,并开展冻融损伤混凝土模型单轴压缩仿真模拟。将数值模拟得到的颗粒轴向位移与试验得到的轴向压缩变形进行对比,验证模型与所标定细观参数的正确性。通过研究颗粒间的接触力和裂纹发展过程,分析冻融损伤对混凝土力学性能的影响。结果表明:随着冻融次数的增加,第二阶段点颗粒间接触力最大值逐渐减小,第三阶段点颗粒间接触力最大值逐渐增大;第二阶段点冻融150次颗粒之间的最大接触力相比于冻融75次颗粒之间的最大接触力降低4%,第三阶段点冻融150次颗粒之间的最大接触力相比于冻融75次颗粒之间的最大接触力增大7.8%;随着冻融次数的增加,混凝土模型中的裂纹数量逐渐增多。不同阶段点对应的颗粒间接触力和裂纹发展可以反映出混凝土的细观破坏程度。因此,可以采用数值试验研究冻融混凝土的细观破坏过程。According to the thickness of concrete damage layer measured by freeze-thaw cycle test,a numerical model of freeze-thaw damaged concrete is established by using discrete element software.Based on the stress-strain curve obtained from uniaxial compression test,the meso-parameters of cement mortar in concrete and the weak contact surface between cement mortar and coarse aggregate are calibrated under different freeze-thaw cycle times.The freeze-thaw damage concrete model is simulated by uniaxial compression.The axial displacement of particles obtained by numerical simulation is compared with the axial compression deformation obtained by experiments to verify the correctness of the model and the calibrated meso-parameters.By studying the contact force between particles and the process of crack development,influence of freeze-thaw damage on the mechanical properties of concrete is analyzed.Results show that with the increase of the number of freeze-thaw times,the maximum value of contact force between particles at the second stage decreases gradually,and the maximum value of contact force between particles at the third stage increases gradually.In the second stage,the maximum contact force between particles for 150 times of point freezing-thawing decreased by 4%compared with the maximum contact force between particles for 75 times of point freezing-thawing,and in the third stage,the maximum contact force between particles for 150 times of point freezing-thawing increased by 7.8%compared with the maximum contact force between particles for 75 times of point freezing-thawing.With the increase of freeze-thaw times,the number of cracks in the concrete model increases gradually.The contact force between particles and crack development at different stage points can reflect the meso-failure degree of concrete.Therefore,numerical experiments can be used to study the meso-failure process of freeze-thaw concrete.

关 键 词：混凝土 冻融损伤 单轴压缩试验 离散元 细观破坏 

分 类 号：TU528[建筑科学—建筑技术科学]