煤矿堵漏风生物自修复材料及其性能调控机理

Because current air-sealing materials are prone to cracking under the effect of pressure, in this project, an innovative microbial air-sealing material is developed. First, the microbial organisms are introduced into the cement mortar. Once cracking occurred, the dormant microorganisms are quickly activated, inducing the precipitation of calcium carbonate and resulting in the filling of cracks, thus completing the healing process. Urease-producing bacteria with outstanding mineralization ability are selected, and the effect of the environmental factors on the mineralization ability of such bacteria is analyzed. The nitrogen-fixing process of phosphate is examined, revealing the biomineralization mechanism. Next, the biocompatibility between the wall material and the bacteria is analyzed using microencapsulated bacteria, and the effects of the material ratio, reaction temperature, and other factors on the microencapsulation properties are investigated to identify the optimal microencapsulation technology. To study the effect of the microcapsule content on the workability and the mechanical properties of the cement material, a computer simulation technique is used. Using this technique, the effects of the microcapsule scale, content, and other characteristics on self-healing efficiency of material are simulated and the control mechanisms behind the self-healing function of microbial organisms are identified. The binding mechanism between the bacteria-induced mineralization product and the sand grains is studied, and the crack-healing process is analyzed using X-ray computed tomography, and a precipitation model of the bacteria-induced mineralization product in concrete cracks is established to reveal the crack-healing mechanisms of the microbial self-healing materials. This study provides a theoretical basis for the use of the self-healing materials for air-sealing applications in mining.

针对现有堵漏风材料在矿压作用下容易产生漏风裂隙的问题，本项目创新性地提出了“堵漏风生物自修复材料”，即将微生物引入水泥砂浆中，一旦材料开裂，休眠的细菌迅速被激活，诱导产生碳酸钙沉淀，主动填充裂缝。本研究拟筛选矿化能力突出的产脲酶细菌，分析井下环境对细菌矿化能力的影响，揭示细菌矿化成岩的机理；利用磷酸盐吸收矿化过程产生的氨气，阐明磷酸盐的固铵机制；利用微胶囊包覆细菌，分析微胶囊壁材与细菌的生物相容性，探讨物料配比、反应温度等对微胶囊性能的影响，明确微胶囊包覆细菌的最优工艺；研究微胶囊掺量对水泥工作性能和力学性能的影响，建立愈合概率几何模型，优化微胶囊的几何尺寸和掺量，揭示生物自修复材料的性能调控机制；研究细菌矿化产物对砂粒的胶结机理，借助计算机断层扫描技术分析裂隙的愈合过程，建立矿化产物在裂缝中的沉积模型，揭示生物自修复材料的裂缝愈合机理，为该材料在煤矿堵漏风领域的应用提供理论基础。

本研究针对现有堵漏风材料在矿压作用下容易产生漏风裂隙的问题，采用实验室试验、理论分析和数值模拟的方法，研发了一种煤矿堵漏风生物自愈合材料。首先，筛选出了一种矿化能力突出的产脲酶细菌，研究了pH值、营养物质、温度、Ca2+和尿素浓度等因素对细菌的生长活性、酶活性等的影响规律及矿化产物特征，明确了细菌的最佳生长环境，研究发现细菌矿化产物为方解石型碳酸钙。其次，选取电石渣、粉煤灰以及水玻璃等作为生物胶囊的壁材，菌粉、酵母粉、黄原胶等作为生物胶囊的芯材，研究了生物胶囊的防水性及其与细菌的生物相容性，明确了生物胶囊包覆细菌的最优工艺参数，结果表明胶囊中细菌存活率为80.61 %；生物胶囊破裂后，在一定的环境下细菌孢子可以萌发生长，并且诱导碳酸钙矿化。然后，通过在水泥砂浆中掺加生物胶囊，制备了堵漏风生物自修复材料，研究了微胶囊掺量对材料稠度、凝结时间、力学性能的影响规律，利用光学显微镜探讨了微胶囊与水泥材料的断裂匹配性；通过裂缝填充效果和透水性测试等评价了裂缝的愈合效果，研究发现：生物胶囊添加量为5 %时，对水泥砂浆性能影响最小；掺加生物胶囊的试样在愈合后其透水性比未掺加试样的透水性低两个数量级。最后，研究了细菌矿化产物与砂粒间的界面结构、Si电子结合能等参数，探讨了细菌矿化产物与松散砂粒间的胶结机理；借助计算机断层扫描技术（X-CT）阐明了材料裂隙的愈合过程；通过数值模拟方法探明了氧气在裂缝中的扩散规律以及裂缝的自修复机理，结果表明，裂纹中氧气的扩散速率明显高于基体中的扩散速率。本项目的实施为该材料在煤矿堵漏风领域的应用提供了理论基础。