基于介观传输格构网络的混凝土冻融热湿耦合模型  

Thermo-Hydro Coupled Model of Concrete Under Freeze-Thaw Cycles Based on Mesoscopic Flow Lattice Network

作　　者：张力 沈雷[1] 张继勋[1] 董义佳 徐磊[1] NIZAR FAISAL ALKAYEM ZHANG Li;SHEN Lei;ZHANG Jixun;DONG Yijia;XU Lei;NIZAR FAISAL ALKAYEM(College of Hydraulic Conservation and Hydropower Engineering,Hohai University,Nanjing 210024,China)

机构地区：[1]河海大学水利水电学院,南京210024

出　　处：《硅酸盐学报》2024年第11期3372-3382,共11页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(52109159,52250410359);江苏省科协青年科技人才托举工程(TJ-2023-043)。

摘　　要：寒区水工混凝土结构经历冻融循环而产生性能劣化,但冻融损伤的力学主导机理并不明晰。采用考虑混凝土介观材料非均质性的传输格构网络空间离散化方法,引入与温度相关的孔隙特性表征系数,提出混凝土冻融循环热湿耦合模型,实现均匀与非均匀温变条件下冻融过程中冰含量滞回现象模拟分析。在利用均匀温变冰含量试验与变形量试验验证了所提模型后,针对非均匀温变冻融循环作用,分析了温度、冰含量、相对湿度、孔隙压力、冻胀应变随冻融次数和冷端距离的变化规律。在水分结冰-融化的过程中,孔隙内冰水混合物对固体骨架的力学作用呈现2个阶段。其一以流体压力为主,采用广义有效应力原理计算孔隙压力荷载;其二以固体应力为主,采用多孔介质弹性力学理论计算冻胀变形,作为非应力引起的应变作用于固体整体变形中。Introduction In cold regions,concrete is widely used as a material in hydraulic structures.Its durability is crucial for ensuring the stability of concrete structures over service life.As a porous medium,concrete undergoes freeze-thaw cycles where the water in the pores freezes and expands,causing water migration and pore pressure.This phenomenon results in internal structural damage and thus degradation of concrete performance.Therefore,it is important to analyze the relationship between temperature,humidity,and pore pressure of concrete during the freeze-thaw cycles.Scholars have proposed various mechanism theories,and a general knowledge is given that the thermo-hydro coupled behavior of concrete imposes the major machinal loads inducing the freeze-thaw damage.But the dominant mechanism is still not clear.The hydrostatic pressure theory and the crystallization pressure theory explain the freeze-thaw damage of concrete from the perspective of the effective stress principle of fluids.The theory of poroelasticity explains the freeze-thaw damage of concrete from the perspective of internal pressure and deformation generated by the pores inside the concrete during the formation and thawing of ice crystals.Hence,it is believed that an additional attention should be paid to the combined mechanical effect of solid phase expansion and the load contribution of the fluid phase.By conducting a detailed analysis of pore pressure and ice expansion deformation during the freeze-thaw process,the dominant mechanism of freeze-thaw damage can be further analyzed.Methods The spatial discretization method of flow lattice network(FLN)considering the concrete mesoscopic heterogeneity is adopted to describe the heat transfer and mass transport behavior.Within the framework of FLN,a thermo-hydro coupled model for concrete during the freeze-thaw cycles is proposed and its mechanical mechanism are discussed based on the poroelasticity and effective stress principle.The proposed model implemented into UEL subroutine and solved by standar

关 键 词：传输格构网络 冻融循环 冰含量 孔隙压力 冻胀应变 

分 类 号：TV431[水利工程—水工结构工程]