微生物固化钙质砂机理与强度特性多尺度研究

微生物固化钙质砂是一种利用微生物诱导矿物沉积，胶结钙质砂颗粒而提高强度的绿色环保加固方法，在我国岛礁吹填工程的加固和修复中具有广阔的应用前景；微生物固化钙质砂的胶结-损伤机理与强度特性具有多尺度特征，而国内外相关研究尚不深入，亟需开展系统性多尺度研究。本项目拟通过微生物加固钙质砂，开展颗粒尺度拉-压-剪强度试验、单元尺度压缩-三轴剪切试验与宏观尺度的模型试验；系统研究不同尺度下胶结-破裂机理与破坏模式；建立微生物加固钙质砂的颗粒尺度拉-压-剪破裂方程与单元尺度强度破坏准则；构建全面考虑微生物胶结-结构损伤机理的多尺度力学模型；提出微生物固化钙质砂力学特性的有限元-离散元耦合多尺度计算方法。本项目聚焦于多学科-多尺度机理和理论模型研究，预期研究成果在岩土工程绿色固化方法中具有重要理论和工程实际意义。

Biocementation of calcareous sands is an environment-friendly reinforcement method, which cements calcareous sand with microbially induced carbonate to increase its strength. This method has a promising application prospect in the reinforcement and restoration of dredging islands in the South China Sea. The cementation-damage mechanism and mechanical characteristics of biocemented calcareous sands are multiscale in nature, which has not been thoroughly investigated. Hence, it is urgent to conduct a systematic multiscale study on this topic. Tensile, compressive, and shear strength tests on the particle scale, oedometer tests and triaxial shear tests on element-scale specimens, and physical model tests on the macro scale will be conducted to systematically investigate the multiscale cementation-damage mechanisms and failure patterns. The tensile, compressive and shear failure criteria of the interparticle cementation and yielding surface of the element-scale specimen will be established, based on which a multiscale numerical model comprehensively considering the biocementation effect and microstructure damage will be built. Finally, an FEM-DEM coupled multiscale approach, specifically designed for biocemented calcareous sands, will be established for evaluating its mechanical performance. This project focuses on multidisciplinary and multiscale mechanisms and theoretical models. The expected outputs will advance the green reinforcement theory and promote its engineering application.