高强微生物砂浆机理与工作性能研究

发布时间：2018-06-18 09:42

本文选题：微生物灌浆 + 高强微生物砂浆　；参考：《清华大学》2013年博士论文

【摘要】：微生物灌浆加固劣化砌体结构是在不适合使用石灰、水泥和环氧树脂等传统灌浆材料情况下，在被加固空腔内，原位填充颗粒，使其作为加固材料的骨架，并通过注入微生物和胶凝溶液的方法，在填充颗粒孔隙内诱导生成碳酸钙，胶凝颗粒，形成具有一定强度的微生物砂浆体。本研究主要通过沙柱灌浆模型实验，系统地研究了影响形成微生物砂浆强度的主要因素，并结合微生物加固简化模型、现场灌浆实验和理论模拟分析，找到了制备高强度微生物砂浆的方法，并第一次对各强度等级微生物砂浆的材料、力学性能进行系统、全面的测试与分析，，为微生物灌浆技术应用于高质量砖石砌体文物建筑加固，奠定了坚实的实验和理论基础。本文主要研究工作和贡献如下：首先通过对巴氏芽孢八叠球菌野生株的亚硝基胍诱变、筛选，得到该菌株的诱变株，使其增殖能力和产脲酶能力相对野生株均有所提高，且不同批次菌液脲酶活性离散性较小，可以稳定遗传诱变后的特性。同时，从土壤中分离得到耐受高尿素浓度、高钙离子浓度的产脲酶菌株，其中的UR49D在脲酶活性和单体酶活性方面与巴氏芽孢八叠球菌野生株具有可比性，且原位酶活性保持能力较高。其次，通过沙柱实验优化填充颗粒粒径、菌株类型、胶凝液浓度、灌浆次数等可控灌浆参数，有效控制形成微生物砂浆的单轴抗压强度，并成功得到单轴抗压强度在2MPa到55MPa不同强度的微生物砂浆样品。接着，通过对这些微生物砂浆的单轴抗压、劈裂抗拉、循环荷载抗压、单压疲劳等力学性能测试，以及其材料胶凝矿物晶体结构和孔径分布的分析，表明这种新型材料相对同等单轴抗压强度的水泥-石灰混合砂浆而言，具有更高的劈裂抗拉强度，较好的延性和耐久性好，是一种较理想的原位加固劣化砌体结构灌浆新材料。此外，通过简化加固模型实验和现场试验研究，可以发现微细裂缝的微生物灌浆还有一定困难，而缺失修复和空鼓填充加固相对容易实施；室外施工时，还应注意避免冬季低温施工，以确保微生物活动不受低温环境影响。最后，通过适当简化，可以对相对复杂的颗粒体系微生物砂浆形成过程进行数学建模，并可以实现对沙柱微生物灌浆过程中碳酸钙生成量、尿素浓度、孔隙率等参数变化情况的一维有限元程序模拟，为微生物灌浆提供了一定的理论基础。
[Abstract]:When the traditional grouting materials such as lime, cement and epoxy resin are not suitable for the reinforcement of the masonry structure by microbial grouting, the particles are filled in the strengthened cavity in situ so that it can be used as the skeleton of the reinforcing material. By injecting microorganism and cementing solution, calcium carbonate was induced in the pore of filling particles to form microorganism mortar with certain strength. In this study, the main factors influencing the strength of microbial mortar were systematically studied through the sand column grouting model experiment, and combined with the simplified model of microbial reinforcement, field grouting experiment and theoretical simulation analysis. The preparation method of high strength microbial mortar was found, and the material and mechanical properties of each strength grade microbial mortar were systematically tested and analyzed for the first time. It lays a solid experimental and theoretical foundation for the application of microbial grouting technology to the reinforcement of high quality masonry cultural relics. The main work and contributions of this paper are as follows: firstly, the mutant strain of Bacillus pasteuris was obtained by mutagenesis of nitrosoguanidine. The proliferative ability and urease production ability were improved compared with wild plants, and the dispersion of urease activity in different batches of bacteria was small, which could stabilize the characteristics after genetic mutation. At the same time, urease producing strains with high urea concentration and high calcium concentration were isolated from soil. The urease activity of UR49D was comparable with that of wild strain of Bacillus pasteuris in urease activity and monomer enzyme activity. And the in situ enzyme activity retention ability is higher. Secondly, the parameters of filling particle size, strain type, gel concentration and grouting times were optimized by sand column experiment to effectively control the uniaxial compressive strength of microbial mortar. The samples of microbial mortar with uniaxial compressive strength ranging from 2 MPA to 55 MPA were obtained successfully. Then, the mechanical properties of the microorganism mortar, such as uniaxial compressive resistance, splitting tensile resistance, cyclic load compression resistance, single pressure fatigue, and the crystal structure and pore size distribution of the cemented mineral are analyzed. The results show that the new material has higher splitting tensile strength, better ductility and durability than cement lime mixed mortar with the same uniaxial compressive strength. It is an ideal new material for in-situ strengthening and deterioration masonry structure grouting. In addition, through simplified reinforcement model experiments and field experiments, it can be found that there are some difficulties in microbial grouting of micro-cracks, but it is relatively easy to implement defect repair and empty drum filling reinforcement. We should also avoid low temperature construction in winter to ensure microorganism activity is not affected by low temperature environment. Finally, through proper simplification, the formation process of microbial mortar in relatively complex granular system can be modeled mathematically, and the amount of calcium carbonate and the concentration of urea during microbial grouting of sand column can be realized. The one-dimensional finite element program simulation of porosity and other parameters provides a theoretical basis for microbial grouting.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU578.1

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