混杂纤维喷射混凝土的弯曲韧性试验

发布时间：2018-11-07 18:43

【摘要】：对于喷射混凝土这一脆性材料而言,掺入混杂纤维是有利于改善其韧性的。国内外研究学者多以弯曲韧性作为评价混杂纤维喷射混凝土韧性的重要指标,所采用的试件形式也以梁试件居多,但梁试件并不符合混杂纤维喷射混凝土的应用实际,基于梁试件的混杂纤维喷射混凝土弯曲韧性评价方法也存在一些不足。与梁试件相比,板试件更能贴近混杂纤维喷射混凝土的应用实际,基于板试件的评价方法也能更加客观、准确地反映混杂纤维喷射凝土的弯曲韧性,能更好地为混杂纤维喷射混凝土的设计和施工提供理论参考,但由于相关评价方法编入我国纤维混凝土试验规范的时间相对较晚,故我国研究学者目前所取得的基于板试件的相关研究成果相对较少。通过设计一种固定位移计的连接装置,并采用混杂不同掺量的钢纤维、聚丙烯纤维和高炉微粉的方法制备的混杂纤维喷射混凝土板,本文开展了如下的研究工作:(1)进行了混杂纤维喷射混凝土的抗压强度研究,试验结果表明:与聚丙烯纤维相比,高炉微粉和钢纤维的掺量变化能更明显地改善混杂纤维喷射混凝土的抗压强度。(2)基于圆板弯曲韧性试验和方板弯曲韧性试验,研究混杂纤维喷射混凝土的弯曲韧性随纤维掺量的变化规律,并探讨了板的破坏形式,研究结果表明:钢纤维掺量越高,混杂纤维喷射混凝土的弯曲韧性越好;在钢纤维喷射混凝土中混杂小掺量(0.11%)聚丙烯纤维能够明显改善其弯曲韧性;混杂纤维喷射混凝土板均表现出良好的裂缝控制能力,破坏呈裂而不断的延性破坏。(3)基于方板弯曲韧性试验,研究混杂纤维喷射混凝土的弯曲韧性随高炉微粉掺量的变化规律,研究结果表明:随着高炉微粉掺量的增加,混杂纤维喷射混凝土的弯曲韧性会有提高。(4)对比分析在两个不同形式板的弯曲韧性试验中所取得的试验数据及破坏图片后,发现在这两种试验中所得到的试验变化规律及试件破坏模式间都有比较明显的相似性。
[Abstract]:For the brittle material of shotcrete, mixing with hybrid fiber is helpful to improve its toughness. Most scholars at home and abroad regard flexural toughness as an important index to evaluate the toughness of hybrid fiber shotcrete, and most of the specimens used are beam specimens, but the beam specimens do not accord with the practical application of hybrid fiber shotcrete. The flexural toughness evaluation method of hybrid fiber shotcrete based on beam specimen also has some shortcomings. Compared with the beam specimen, the plate specimen is more close to the practical application of hybrid fiber shotcrete, and the evaluation method based on the plate specimen can reflect accurately the bending toughness of hybrid fiber sprayed clay. It can provide a better theoretical reference for the design and construction of hybrid fiber shotcrete, but the relative evaluation method is relatively late to be compiled into the test code of fiber reinforced concrete in China. Therefore, Chinese researchers have obtained relatively few research results based on plate specimens. The hybrid fiber shotcrete slab was prepared by designing a fixed displacement meter connecting device and mixing steel fiber, polypropylene fiber and blast furnace powder with different amount of steel fiber, polypropylene fiber and blast furnace powder. In this paper, the following research works are carried out: (1) the compressive strength of hybrid fiber shotcrete is studied. The experimental results show that: compared with polypropylene fiber, The compressive strength of hybrid fiber sprayed concrete can be improved more obviously by changing the content of blast furnace powder and steel fiber. (2) based on the bending toughness test of circular plate and square plate, The flexural toughness of hybrid fiber shotcrete with fiber content is studied, and the failure mode of slab is discussed. The results show that the higher the content of steel fiber, the better the flexural toughness of hybrid fiber shotcrete. The flexural toughness of steel fiber sprayed concrete can be improved by mixing polypropylene fiber with low content (0.11%). Hybrid fiber shotcrete slabs all show good crack control ability and continuous ductile failure due to cracking. (3) based on the bending toughness test of square plate, The variation of flexural toughness of hybrid fiber sprayed concrete with the content of blast furnace powder is studied. The results show that: with the increase of blast furnace powder content, The flexural toughness of hybrid fiber sprayed concrete will be improved. (4) after comparing and analyzing the test data and damage pictures obtained from two different forms of bending toughness test, It is found that there are obvious similarities between the experimental changes and the failure modes of the two kinds of tests.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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