人工蛋白纤维增强微生物胶结松散砂的物质变化规律和动态过程机制

Chimeric protein fiber constructed by synthetic biotechnology has the advantages of directional regulation, low cost and durability compared with traditional fibers in the fiber-reinforcing sands consolidation technology. It has great application potential in the microbially induced calcite precipitation (MICP)-cemented-loose sands. At present, chimeric protein fiber using in MICP-cemented-loose sands is in the initial exploration stage, lacking in-depth process and mechanism research. In this project, a keratin-adhesive protein chimeric protein fiber, namely HSKI-MCFP3 constructed from our laboratory formerly, was investigated in the research of fiber reinforcing MICP-cemented-loose sands. Firstly, the cementation parameters were optimized through response surface method, and the dynamic changes of the cementation process were comprehensively analyzed. Based on the convection-diffusion equation, the cementation process was simulated, and the design method of cementation materials and process parameters was established. Secondly, the structure-affect relationship between the structure and strength/toughness of the cement were determined, and the microscopic mechanism were explored through the analysis of the microstructure, thermal stability, functional group and binding energy of the cement. Finally, the dynamic process mechanism of chimeric protein fiber HSKI-MCFP3 enhancing the MICP-cemented-loose sands were clarified through comprehensive analysis of the above results. The project will provide theoretical basis and technical support for the development of artificial chimeric protein fiber materials reinforcing MICP-cemented-loose sands.

在纤维增强固结砂土技术中，运用合成生物技术构建的嵌合蛋白纤维相较于传统纤维具有可定向调控、成本低和耐久性等优势，在微生物诱导碳酸盐沉积（MICP）固结砂土技术中极具应用潜力。目前人工嵌合蛋白纤维增强MICP固结砂土尚处在初始探索阶段，缺乏深入的过程和机制研究。基于此，本项目拟利用实验室已构建的具有胶凝功能的角蛋白-粘胶蛋白嵌合蛋白纤维HSKI-MCFP3开展增强MICP胶结松散砂机制研究。采用响应面法优化胶结参数，综合分析过程中物质变化规律，并以对流-扩散方程模拟胶结过程；明确胶结体结构、矿物组成和含量与强度/韧性之间的构效关系；分析胶结体微结构、热稳定性、官能团和结合能变化规律，探讨微观机制；综合上述结果，进一步阐明嵌合蛋白纤维HSKI-MCFP3增强MICP胶结松散砂的动态过程机制。为开发可定向调控、环保、高效、低成本的人工蛋白纤维材料增强MICP固结砂土技术提供理论基础和技术支撑。

人工嵌合蛋白纤维增强微生物诱导碳酸盐沉积（MICP）是一种低能耗、低排放的绿色固结技术，但缺乏深入的过程和机制研究。本课题首先分别以羊毛纤维、角蛋白、聚谷氨酸（γ-PGA）和黄原胶为研究对象，深入研究并探索蛋白纤维对MICP固结砂土的影响和增强机制。基于此，选取人工嵌合蛋白纤维MFP 151和交联丝素蛋白，探索人工合成蛋白纤维对MICP固结砂土力学性能的影响。. 首先向MICP固结砂土中添加富含α-角蛋白的羊毛纤维（0.1 wt%）后，抗压强度（UCS）最高提高到对照的3.34倍，并显著提高了抗弯性能。基于此，进一步以α-角蛋白为添加剂，验证了蛋白类添加剂对MICP固结砂土力学性能具有提高作用。以上研究都发现细菌分泌的有机物或者蛋白质通过分子间氢键HN-H…O-C（Si）固结砂粒和方解石。蛋白类添加剂可以促进方解石沉淀，从而提高砂粒对载荷的抵抗力。蛋白类物质固有的弹性特性，可以提高试样的韧性。因此，选取具有黏性和水可分散性的两种阴离子生物聚合物γ-PGA和黄原胶，分别对MICP固结砂土的力学性能和潜在机理进行了研究。结果发现，向MICP固结砂土中添加0.1-9 g/L γ-PGA可将抗压强度提高到对照的1.54-3.96倍，并显著降低脆性。黄原胶也可以有效增强MICP固结效果。. 基于以上研究结果，选取人工嵌合蛋白纤维MFP 151和交联丝素蛋白，探索人工合成蛋白纤维对MICP固结砂土力学性能的影响。结果发现，MFP 151可以将MICP固结砂土的UCS和韧性分别提高到对照的2.43倍和2.13倍。在MICP处理前，将0.05%vt戊二醛、交联试剂和1%wt丝素蛋白加入到松散砂土中，UCS和抗弯强度分别最高提高到对照的2.77倍和4.10倍。通过细胞活力测试和转录组分析，首次发现戊二醛的弱毒性环境具有一定程度的细菌活力刺激。本研究探索了人工合成蛋白纤维添加剂在提高MICP固结砂土力学性能中的作用，为开发可定向调控、环保、高效、低成本的人工合成蛋白纤维材料增强MICP固结砂土技术提供理论基础和技术支撑。

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