| 纤维加筋MICP固化钙质砂的抗拉强度特性研究 |
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| 引用本文： | 王殿龙,唐朝生,泮晓华,刘 博,李 昊,吕 超,程瑶佳.纤维加筋MICP固化钙质砂的抗拉强度特性研究[J].高校地质学报,2021,27(6):670-678. |
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| 作者姓名： | 王殿龙 唐朝生 泮晓华 刘 博 李 昊 吕 超 程瑶佳 |
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| 作者单位： | 南京大学 地球科学与工程学院,南京 210023 |
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| 基金项目： | 国家自然科学基金;国家自然科学基金;国家自然科学基金;国家自然科学基金;江苏省自然科学基金;中央高校基本科研业务费专项 |
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| 摘 要： | 针对微生物诱导碳酸钙沉积 (MICP)固化钙质砂脆性强、抗拉强度低等问题，通过制备“8”字形MICP固化钙质砂试样并开展直接拉伸试验，对纤维加筋的改善作用、纤维-MICP联合加固机理及纤维掺量、纤维长度等影响因素进行了研究。结果表明：纤维加筋能够显著提高抗拉强度、峰值位移和残余强度，减轻峰值强度点的脆性破坏现象，但受纤掺量和长度的影响，总的来说，抗拉强度随纤维掺量的增加和长度的加长呈先增后减的趋势。相比无纤维试样，添加最优纤维掺量（0.6%）时，试样的抗拉强度增长了172.4%，峰值变形提升了158.1%。机理可解释为纤维增加了微生物的吸附量，促进碳酸钙在纤维与钙质砂之间以及纤维表面的沉积，增大纤维与钙质砂之间的界面作用力，整体提升钙质砂的抗拉强度特性。纤维的添加能够显著改变试样的变形特征，无纤维添加试样曲线仅有初始误差阶段和弹性阶段两个阶段，添加纤维后曲线表现为四个阶段包括初始误差阶段、弹性阶段、损伤破坏阶段和残余阶段。纤维掺量影响的内因是纤维与钙质砂的界面作用力和纤维空间分布状态随纤维掺量的变化而变化，纤维长度的影响主要和破坏面附近纤维数量和单位长度所能承担的拉应力相关。研究成果对以钙质砂为地基的岛礁工程的稳定性、安全性具有一定的指导意义。
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| 关 键 词： | 钙质砂 MICP 纤维加筋 碳酸钙含量 抗拉强度 |
Tensile Strength of Fiber-reinforced Micp-treated Calcareous Sand |
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| WANG Dianlong,TANG Chaosheng,PAN Xiaohua,LIU Bo,LI Hao,LYU Chao,CHENG Yaojia.Tensile Strength of Fiber-reinforced Micp-treated Calcareous Sand[J].Geological Journal of China Universities,2021,27(6):670-678. |
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| Authors: | WANG Dianlong TANG Chaosheng PAN Xiaohua LIU Bo LI Hao LYU Chao CHENG Yaojia |
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| Institution: | School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China |
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| Abstract: | The microbially induced carbonate precipitation (MICP) treated calcareous sand tends to be brittle and has low tensile strength. To solve this problem, a special “8” shaped mold was designed and a series of direct tensile tests were conducted to investigate the improvement of fiber reinforcement, the mechanism of fiber-reinforced MICP-treated, and influencing factors such as fiber content and fiber length. The results showed that fiber can improve tensile strength, peak displacement, and residual strength and reduce brittle failure. Overall, the tensile strength of fiber-reinforced MICP-treated calcareous sand samples was influenced by the fiber content and fiber length, the tensile strength tended to increase and then decrease with increasing fiber content and fiber length. Compared to the unreinforced sample, the tensile strength of the sample with 0.60% fiber content (the optimum fiber content) increased by172.40%，the peak displacement increased by 158.1%. The mechanism of fiber reinforcement can be explained by the fact that the fiber increased the amount of adsorption of Sporosarcina pasteurii, promoted the precipitation of calcium carbonate between the fibers and calcareous sand and the surface on the fibers, increased the interfacial forces between the fiber and the calcareous sand, improved the tensile strength of MICP-treated calcareous sand. Fiber can significantly alter the failure characteristics of samples, the tensile stress-displacement curve of the unreinforced sample had only two phases, and an initial phase, and an elastics phase, the curves of fiber-reinforced samples could be characterized by four phases including an initial phase, an elastic phase, a damage phase, and a residual phase. The effect of fiber content was mainly related to the interfacial forces between the fibers and calcareous sand, and the spatial disturbution of fibers. The effect of fiber length was mainly related to the number of fibers near the failure surface and the tensile stress per unit length of fiber could bear. Furthermore, the results of this study have certain guiding significance for the stability and safety of oceanic projects. |
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| Keywords: | calcareous sand microbial induced carbonate precipitation (MICP) fiber reinforcement calcium carbonate content
tensile strength
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