| 摘要: |
| 通过跨度和初始缝高比恒定的三点弯曲梁试验,计算不同自燃煤矸石粗集料取代率下混凝土的断裂韧度和断裂能,用特征长度和延性指数来衡量其脆性与延性.基于图像处理技术,在水平投影方向对断裂面混合粗集料的分布及破坏方式进行分析.通过三维重构断裂面形貌计算相应分形维数，用以表征粗集料表面粗糙度.结果表明：自燃煤矸石粗集料混凝土的弯曲破坏特征与普通混凝土相似,但随着取代率的增大,裂缝发展路径由弯曲扩展向竖直扩展转变,贯穿截面所用时间变短;韧性参数皆随取代率增大而降低,但降幅不同,当取代率为25%时,特征长度及延性指数与普通混凝土持平,之后随取代率增大而下降,当取代率达到100%时,起裂断裂韧度、失稳断裂韧度和断裂能较普通混凝土分别下降1169%、3904%、4786%.取代率变化对混合粗集料与断裂带净面积水平投影之比影响不明显,但对混合粗集料断裂破坏比例影响显著.随着取代率的增大,分形维数逐渐降低,断裂面形貌渐趋平整.自燃煤矸石粗集料对混凝土断裂性能产生明显不利影响,断裂特征较普通混凝土显著,在工程中应予以高度重视. |
| 关键词: 自燃煤矸石粗集料 取代率 混凝土断裂性能 图像处理 |
| DOI：103969/j.issn.1007 9629202004018 |
| 分类号: |
| 基金项目:国家自然科学基金联合资助项目(U1261122)；国家自然科学基金资助项目(51808352)；辽宁省教育厅科学技术项目（LJ2019FL006） |
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| Effect of Spontaneous Combustion Coal Gangue Coarse Aggregate Replacement Ratio on Fracture Properties of Three Point Bending Concrete Beam |
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YANG Shangyu1, ZHOU Mei1, ZHANG Yuzhuo2, ZHANG Yuanqiang1, ZHANG Boqun1
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1.College of Civil Engineering, Liaoning Technical University, Fuxin 123000, China;2.College of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China
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| Abstract: |
| The fracture toughness and fracture energy of concrete with different spontaneous combustion coal gangue coarse aggregate replacement ratios were calculated by three point bending beam test with constant span and initial incision depth ratio.The brittleness and ductility of concrete were measured by characteristic length and ductility index. Based on image processing technology, the distribution and failure mode of mixed coarse aggregate on fracture surface were quantitatively analyzed in horizontal area projection direction. The surface roughness of coarse aggregates was characterized by calculating fractal dimension through three dimensional reconstruction of fracture surface morphology. The results show that the bending failure characteristics of spontaneous combustion coal gangue coarse aggregate concrete are similar to those of ordinary concrete. As the replacement ratio increases, the development path of the crack changes from bending to vertical, and the time taken for the crack to penetrate the section is gradually shortened, the toughness parameters decrease with the increase of replacement ratio, but the decreases are different. When the replacement ratio is 25%, the characteristic length and the ductility index are the same as ordinary concrete, and then decrease with the increase of replacement ratio. When the replacement ratio reaches 100%, the initial fracture toughness, unstable fracture toughness and fracture energy are 1169%, 3904% and 4786%, respectively, compared with ordinary concrete. The change of replacement ratio has no obvious effect on the ratio of mixed coarse aggregate to the horizontal area projection of fracture surface, but the effect on the fracture failure ratio of mixed coarse aggregate is significant. With the increase of replacement ratio, the fractal dimension gradually decreases, and the fracture surface morphology gradually becomes flat.The spontaneous combustion coal gangue coarse aggregate has a significant adverse effect on the fracture properties of concrete. The fracture characteristics are more significant than those of ordinary concrete, and should be highly valued in the project. |
| Key words: spontaneous combustion coal gangue coarse aggregate replacement ratio concrete fracture property image processing technology |
