应变硬化尾矿砂水泥基复合材料断裂特性分析

发布时间：2018-05-13 17:40

本文选题：应变硬化 + 尾矿砂　；参考：《沈阳工业大学》2017年硕士论文

【摘要】：当前,应变硬化水泥基复合材料在海洋、高低温等复杂环境下建筑的应用越来越多。研究应变硬化尾矿砂水泥基复合材料(Strain-Hardening Tailings Cementitious Composites,简称SHTCC)断裂时的应力强度因子及能量因子,进而评估带缝构件的寿命及安全性是工程界极为关注的问题。本课题基于非线性断裂力学理论及双K断裂准则,在常态、冻融及硫酸盐腐蚀三种情况下,对SHTCC进行三点弯曲断裂试验,主要研究内容是:(1)基于数字图像相关方法,采用非接触视频测量仪对三点弯曲梁全过程中试件观测面的位移场及应变场进行观测。通过检验水泥砂浆试验结果以说明采用此方法确定试件起裂荷载的合理性,进而基于该方法总结SHTCC材料起裂荷载与极限荷载比值的范围,为后续研究作为参考。(2)研究在常态下SHTCC的断裂性能。主要研究试件尺寸、粉煤灰掺量、尾矿砂掺量、纤维掺量、水胶比等因素对断裂参数的影响。研究表明,试件尺寸对断裂参数几乎没有影响;粉煤灰掺量为54.5%断裂参数最大;替换率为50%的尾矿砂作为细骨料对断裂参数几乎无影响;纤维掺量2%、水胶比0.4时SHTCC的起裂断裂韧度最大,纤维掺量2%、水胶比0.5时SHTCC的失稳断裂韧度及断裂能最大。(3)研究冻融循环作用下SHTCC的断裂性能。主要研究冻融循环次数、纤维掺量、水胶比等因素对断裂参数的影响。研究表明,在冻融循环条件下,SHTCC试件的起裂断裂韧度是水泥砂浆的2倍左右,失稳断裂韧度是水泥砂浆的10倍左右,断裂能是水泥砂浆的100倍左右。(4)研究干湿循环硫酸盐腐蚀作用下SHTCC的断裂性能。主要研究干湿循环腐蚀次数、纤维掺量、水胶比等因素对断裂参数的影响。研究表明,在硫酸盐腐蚀条件下,SHTCC试件的起裂断裂韧度是水泥砂浆的2倍左右,失稳断裂韧度是水泥砂浆的10倍左右,断裂能是水泥砂浆的100倍左右。从断裂力学的角度分析,相对于水泥砂浆而言,在诸如冻融循环以及硫酸盐腐蚀的恶劣环境下,SHTCC材料具有卓越的断裂特性。
[Abstract]:At present, strain-hardening cement-based composites are used more and more in complex environments such as ocean, high and low temperature. It is very important to study the stress intensity factor and energy factor of strain-Harding Tailings Cementitious Composites, during the fracture of strain-hardening tailings cement-based composite material, and to evaluate the life and safety of jointed members. Based on the theory of nonlinear fracture mechanics and double K fracture criterion, the three-point bending fracture test of SHTCC is carried out under normal, freeze-thaw and sulfate corrosion conditions. The main research content is: 1) based on digital image correlation method. The displacement field and strain field of the observed plane in the whole process of three-point bending beam were observed by the contactless video measuring instrument. The test results of cement mortar show that the method is reasonable to determine the crack initiation load of the specimen, and then the range of the ratio of the initial crack load to the ultimate load of SHTCC material is summarized based on this method. The fracture properties of SHTCC under normal condition were studied as a reference for further study. The effects of sample size, fly ash content, tailings content, fiber content and water-binder ratio on fracture parameters were studied. The results show that the size of the specimen has little effect on the fracture parameters, the content of fly ash is 54.5% and the tailings with a replacement ratio of 50% have little effect on the fracture parameters. The fracture properties of SHTCC under freezing and thawing cycles were studied by using the following parameters: the maximum initial fracture toughness of SHTCC was obtained when the fiber content was 2 and the ratio of water to binder was 0.4. The fracture toughness and the maximum fracture energy of SHTCC under freeze-thaw cycle were studied when the fiber content was 2 and the ratio of water to binder was 0.5. The effects of freezing and thawing cycle times, fiber content and water / binder ratio on fracture parameters were studied. The results show that the initial fracture toughness of SHTCC specimen under freeze-thaw cycle is about 2 times of that of cement mortar, and the instability fracture toughness is about 10 times that of cement mortar. The fracture energy is about 100 times of that of cement mortar.) the fracture properties of SHTCC under dry and wet cycle sulphate corrosion are studied. The effects of dry and wet cycle corrosion times, fiber content and water / binder ratio on fracture parameters were studied. The results show that the initial fracture toughness of SHTCC specimen is about 2 times of that of cement mortar, the instability fracture toughness is about 10 times that of cement mortar, and the fracture energy is about 100 times that of cement mortar under sulphate corrosion condition. From the point of view of fracture mechanics, compared with cement mortar, SHTCC materials have excellent fracture characteristics under harsh conditions such as freeze-thaw cycle and sulphate corrosion.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332

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