温度场与硫酸盐侵蚀耦合作用混凝土孔结构分形特征演化规律  

Evolution of Fractal Characteristics of Concrete Pore Structure Under Coupling Effect of Temperature Field and Sulphate Attack

作　　者：张少辉 王艳 郭冰冰 吕瑶[2] 牛荻涛[2,3] ZHANG Shaohui;WANG Yan;GUO Bingbing;LV Yao;NIU Ditao(School of materials science and engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;School of civil engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;State Key Laboratory of Green Building,Xi'an University of Architecture and Technology,Xi'an 710055,China)

机构地区：[1]西安建筑科技大学材料科学与工程学院,西安710055 [2]西安建筑科技大学土木工程学院,西安710055 [3]绿色建筑全国重点实验室,西安710055

出　　处：《硅酸盐学报》2024年第2期474-484,共11页Journal of The Chinese Ceramic Society

基　　金：国家优秀青年科学基金(52222806);陕西省杰出青年科学基金(2022JC-20);国家自然科学基金(52078413);西安建筑科技大学优秀博士学位论文培育基金(2021XYBPY004)。

摘　　要：高地热环境隧道衬砌混凝土耐久性劣化是混凝土内部温度场与硫酸盐侵蚀耦合作用的结果。设计了耦合作用室内模拟制度与装置,采用分区分形维数研究了耦合作用孔表面粗糙度、孔结构复杂性与孔曲折度,分析了分形维数对混凝土整体强度与损伤层平均抗压强度的影响权重与关系。结果表明:耦合作用混凝土整体抗压强度比单因素作用下降22.5%~30.0%。随温度场从40℃升高到80℃,耦合作用混凝土中凝胶孔(<10nm)占比下降43.17%,毛细孔(100~1000nm)占比增加573.10%。过渡孔(10~100 nm)表面变得更为粗糙,凝胶孔与过渡孔空间结构比毛细孔和大孔(≥1000 nm)更加复杂,凝胶孔、过渡孔、毛细孔曲折度增加但大孔曲折度下降。过渡孔与大孔表面粗糙度、凝胶孔结构复杂性对损伤层混凝土平均抗压强度影响最为显著。大孔、毛细孔与过渡孔的孔体积分形维数与整体混凝土抗压强度呈负线性相关,毛细孔、过渡孔与凝胶孔的Ds对整体混凝土抗压强度影响存在极值。Introduction During the long-term service of the tunnel in high-geothermal environment,one side of the lining structure is in contact with the high-temperature rock wall,and another side is the normal temperature opening area of the tunnel.The temperature field is formed inside the lining concrete.The durability deterioration of lining concrete is the result of the coupling effect of temperature field and sulfate attack.The existence of temperature field under the coupling effect accelerates the diffusion of SO_(4)^(2-)from the outside to the inside of concrete as well as the chemical reaction and damage degree of attack.The deterioration mechanism of sulfate attack in high-geothermal environment is different from that in normal temperature environment.However,an indoor simulation test in high-geothermal environment adopts a hot sulfate solution soaking method.Although this method can achieve the acceleration of high temperature,it cannot simulate the effect of temperature field.The concrete corner is subjected to two-way high temperature under the method of hot sulfate solution immersion,resulting in more serious corner deterioration.Therefore,the scientific basis and rationality of the hot sulfate solution soaking method are still debatable.In addition,the pore structure characteristics of concrete are a key to affecting sulfate attack.The existing research on the pore structure of sulfate attack concrete mostly adopts the index of pore size distribution and its corresponding pore content,which cannot fully reflect the mechanism of sulfate attack.Fractal theory is proved to quantitatively characterize the complexity and irregularity of the pore structure of cement-based materials,and can also link the pore structure characteristics of cement-based materials with macroscopic properties.Therefore,this paper proposed a durability simulation system for the coupling of one-dimensional temperature field and sulfate attack.A fractal dimension method was used to investigate the pore structure characteristics of lining

关 键 词：高地热环境 衬砌混凝土 温度场作用 硫酸盐侵蚀 耦合作用 分形 

分 类 号：TU528[建筑科学—建筑技术科学]