【作者】 王占桥；

【导师】 高丹盈； 朱海堂；

【作者基本信息】 郑州大学 ， 水工结构工程， 2004， 硕士

【摘要】 随着纤维混凝土的广泛应用和结构分析方法、试验技术、设计方法等的日臻完善，纤维混凝土断裂机理的研究已经引起了广大科技工作者的广泛重视。本文在河南省自然科学基金（0311052800）资助下，主要进行了以下几个方面的研究： 1．通过24组共72个试件尺寸为200mm×170mm×100mm的楔劈拉伸试件的试验，探讨了钢纤维体积率、钢纤维类型、相对切口深度等对高强混凝土断裂性能的影响，建立了钢纤维高强混凝土断裂韧度(K_IC)、断裂能（G_F）、临界裂缝嘴张开位移（CMOD_C）、临界裂缝尖端张开位移（CTOD_C）等断裂参数与钢纤维含量特征参数的关系式；分析了钢纤维高强混凝土和普通高强混凝土的缺口敏感性以及钢纤维对高强混凝土裂缝前缘应变场分布的影响。试验结果表明：钢纤维的加入可以极大地改善高强混凝土的断裂性能，随着纤维体积率的增加，钢纤维高强混凝土断裂参数均有不同程度的提高；与铣削型和剪切波纹型钢纤维相比，切断弓型钢纤维可以极大地改善高强混凝土的断裂性能；钢纤维高强混凝土断裂韧度和断裂能存在缺口敏感性，钢纤维体积率的变化对高强混凝土缺口敏感性的影响较小；钢纤维的加入可以改善裂缝前缘应变场分布。 2．通过8组共24个试件尺寸为200mm×170mm×100mm楔劈拉伸试件的试验，探讨了聚丙烯纤维掺量对高强混凝土断裂韧度、断裂能和临界裂缝嘴张开位移的影响，研究了聚丙烯纤维高强混凝土裂缝前缘应变场分布。结果表明：在本次试验条件下，聚丙烯纤维对高强混凝土断裂韧度基本没有影响，但可以提高高强混凝土的断裂能和临界裂缝嘴张开位移；随着纤维掺量的增加，断裂能和断裂能增益比都有不同程度的提高，临界裂缝张开位移有减小的趋势，临界裂缝嘴张开位移增益比变化没有明显的规律性；聚丙烯纤维对高强混凝土试件裂缝前缘应变场分布改善不显著；聚丙烯纤维主要改善高强混凝土的裂后行为。 3．通过对14组共42个混杂纤维高强混凝土楔劈拉伸试件的试验，研究了混杂纤维高强混凝土的断裂力学性能和纤维混杂效应。研究结果表明：纤维的加入可以极大地改善高强混凝土的断裂性能，纤维掺量较小的混杂纤维高强混凝土表现了纤维的正混杂效应，随着纤维掺量的增加，纤维的混杂效应逐渐消失；钢纤维在混杂纤维高强混凝土断裂性能的改善方面起着主导作用，聚丙烯纤维对高强混凝土断裂性能的改善有局限性，弓型纤维对混杂纤维高强混凝土断裂性能的改善较为有效。更多还原

【Abstract】 With the extensive use of fiber reinforced concrete and the development of structural analysis method, experimental technique, design means, the research on the fracture properties of fiber reinforced concrete has been extensively regarded. As the project supported by the Natural Science Foundation of HENAN Province (0311052800), the following research works have been accomplished in this paper:1 .By the wedge-splitting tensile test on seventy-two specimens of steel fiber reinforced high-strength concrete (HSC) with the size of 200mmxl70mmx 100mm, the impacts of steel fiber volume ratio, notch depth ratio and different types of steel fiber upon the fracture properties, such as critical stress intensity factor (K\c), fracture energy (Gf), critical crack mouth opening displacement (CMODc) as well as critical crack tip opening displacement (CTODc) of HSC have been studied. The correlativity between steel fiber aspect ratio and fracture properties of HSC reinforced with steel fiber has been established. The notch sensitivity of HSC and steel fiber reinforced HSC and the strain field of HSC reinforced with steel fibers ahead of the crack tip have been analyzed. The test results indicated that the addition of steel fiber can significantly improve the fracture properties of HSC. As the increase of steel fiber volume ratio, the fracture parameters of steel fiber reinforced HSC increase differently. In comparison with the milled steel fiber and waved steel fiber, the addition of bowed steel fiber to HSC improves its fractural properties more. The HSC and steel fiber reinforced HSC are all have notch sensitivity. The addition of steel fiber to the HSC has extensively improved the strain filed ahead of the crack tip.2. By the wedge-splitting tensile test on the twenty-four specimens of polypropylene fiber reinforced HSC with the size of 200mmx170mmx 100mm, the impacts of polypropylene dosage upon the fracture properties, such as stress intensity factor, fracture energy, as well as critical crack mouth opening displacement of polypropylene reinforced HSC have been investigated, and the strain field ahead of the crack tip of polypropylene fiber reinforced HSC has been researched. The test results indicate that the addition of polypropylene has no impacts upon the KIC, but increases the GF and CMODc. With the increase dosage of polypropylene, GV and the increment ratio of GF increase respectively, but CMODc decreased, and the varying of increment ratio of CMODc has no disciplinarian, and the influence of strain field ahead of crack tip is small. Polypropylene improves the properties of HSC at the post-cracking zone.3. By the wedge-splitting tensile test on the forty-two specimens of hybrid (steel and polypropylene) fiber reinforced HSC with the size of 200mmx 170mmx 100mm, the fracture properties of hybrid fiber reinforced HSC and the synergy effect on HSC have been investigated.The test results indicate that the addition of fiber has extensively improved the fracture properties of HSC. A positive synergy effect between steel fiber and polypropylene has been observed at low fiber dosage and the synergy effect disappears with the increase of fiber dosage. Steel fiber plays a key role on the improvement of fracture properties of hybrid fiber reinforced HSC. The improvement effect of polypropylene on the fracture properties of hybrid reinforced HSC is small. Bowed steel fiber is more effective on the improvement of fracture properties of hybrid fiber reinforced HSC than other two types of steel fiber.更多还原