| 蒋京泰,李地元*,汪小东,余一松,王勇兵,方旭刚.钢纤维混凝土力学性能优化与裂纹扩展特性试验研究[J].实验力学,2023,38(4):455~466 |
| 钢纤维混凝土力学性能优化与裂纹扩展特性试验研究 |
| Experimental study on mechanical properties and crack propagation characteristics of steel fiber reinforced concrete |
| 投稿时间：2022-08-31 修订日期：2022-10-06 |
| DOI：10.7520/1001-4888-22-212 |
| 中文关键词: 钢纤维混凝土 抗折强度 数字图像相关 裂纹扩展 |
| 英文关键词:steel fiber reinforced concrete flexural strength digital image correlation crack propagation |
| 基金项目:国家自然科学基金项目(No. 52074349)；校企合作项目：超深井高地压复杂环境下开采关键技术研究 |
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| 中文摘要: |
| 为探究复掺钢纤维下混凝土力学性能和裂纹扩展特性，利用云南某深部矿山现场所取的砂、石、水泥等材料制成不同钢纤维掺量的混凝土试样，通过四点弯曲、劈裂拉伸和单轴压缩等试验获取试样抗折、抗拉和抗压强度，并借助数字图像相关技术(DIC)分析试样破坏和表面应变演化特征，优选出钢纤维混凝土配方应用于矿山竖井衬砌支护。同时对观测图像进行形态学处理，求算裂纹长度与裂纹扩展速度。试验结果表明：相较于对照组，添加钢纤维后混凝土试样的抗拉强度提升了46%～83%、抗折强度提升了24%～39%。钢纤维混凝土配方中，三掺钢纤维配方(40kg/m3长纤维，5kg/m3中长纤维，10kg/m3短纤维)对混凝土抗拉、抗折强度提升效果最佳，对残余强度和韧性指数的提升幅度最大。随着钢纤维尺寸种类的增加，试样位移-荷载峰后曲线斜率逐渐降低，同时混凝土试样内部固结后形成金属网结构的孔隙度降低，混凝土试样表面剥落量和裂纹衍生数量不断减少，到达峰值荷载时试样最大主应变降低。随着钢纤维种类增加，混凝土表面裂纹扩展平均速度减缓，相对起裂应力(起裂应力与峰值应力比值)逐渐降低，三掺钢纤维混凝土试样相对起裂应力最低(71%峰值荷载)，平均裂纹扩展速度最慢(7.38mm/s)。 |
| 英文摘要: |
| To explore the mechanical properties and crack propagation of concrete with different steel fiber contents, the samples of steel fiber reinforced concrete with different contents were prepared by using materials including sand, stone, and cement from Huize mine in Yunnan province. The flexural, tensile, and compressive strengths of the samples were tested by the four-point bending test, splitting tensile test, and uniaxial compression test. Recording and analysis of specimen failure processes and principal strain evolution with digital image correlation, the preferred steel fiber concrete contents were applied to mine shaft wall lining support. At the same time, the monitored images were subjected to morphological processing, and the crack trajectory length and propagation velocity were calculated. The test results showed that the tensile strength of concrete samples increased by 46%~83% and the flexural strength increased by 24%~39% after adding steel fibers compared to the control group. In the steel fiber concrete formulation, the three-incorporated steel fiber formula (40kg/m3 long fiber, 5kg/m3 medium long fiber, 10kg/m3 short fiber) had the best effect on improving the tensile and flexural strength of concrete. Compared with the formula with single doped steel fiber, the toughness index of the formula with triple doped steel fibers has the highest increase. With the increased of steel fiber types, the slope of the post-peak curve of the sample gradually decreased, the porosity of the metal mesh structure formed by the internal consolidation of the concrete was reduced, the surface spalling amount and the number of crack derivatives on the concrete sample decreased, and the major principal strain of the sample decreased when the peak load was reached; the average speed of crack propagation on the concrete surface slowed down, and the relative cracking stress value gradually decreased. Among them, the relative crack initiation stress of the triple mixed steel fiber concrete sample was the lowest (71%Fmax) and the average crack propagation velocity was the slowest (7.38mm/s). |
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