微生物诱导碳酸钙沉淀改良土性是岩土加固领域研究的热点。开展微生物加固钙质砂的共振柱试验，分析小应变下动模量和阻尼比特性；研究蠕动泵联合超声波振动制备微生物加固钙质砂方法，开展空心圆柱扭剪试验，模拟不同循环加载应力路径，研究复杂动态加载路径下微生物加固钙质砂的强度、变形及孔压增长特性，揭示复杂应力下微生物加固钙质砂的动力学行为；通过扫描电镜监测试验各阶段的试样细观结构，分析颗粒及胶结物状态特征及其统计规律；建立能考虑循环累积损伤作用的微生物加固钙质砂颗粒间三维胶结模型，通过离散元数值模拟研究复杂应力下微生物加固钙质砂的细观结构演变特征，提出细观结构损伤识别和表征方法；基于宏细观参量的相关性分析，揭示主控细观损伤参数随加载应力、累积变形等宏观参量的演变规律，明确微生物加固钙质砂动力响应的宏细观机制。研究成果将为推动微生物加固钙质砂的抗震工程实践提供依据和参考。

The soil improvement technique of microbially induced carbonate precipitation has been the primary focus of research in biogeotechnical engineering to date. The resonant column tests of biocemented calcareous sand are carried out to analyze the shear modulus and damping ratio at small shear strain range. A peristaltic pump combined with ultrasonic vibration method to prepare biocemented calcareous sand is proposed. The hollow cylinder torsion shear tests are performed to investigate the cyclic strength, deformation and pore pressure properties under complex cyclic loading conditions and stress paths. Then the dynamic behavior of biocemented calcareous sand under complex stress conditons will be revealed. The mesoscopic structures of biocemented calcareous sand in every loading stage are monitored by scanning electron microscopy, and the statistical state characteristics of sand particles and biocements are analyzed. A three-dimensional biocementation model considering cyclic cumulative degradation is established. The mesostructural evolution characteristics of biocemented calcareous sand under complex stress conditions are investigated by discrete element numerical simulation. A mesostructural degradation recognization and characterization method is proposed. Based on the correlation analysis method between macroscopic and mesoscopic parameters, the evolution law of the main mesoscopic degradation parameter with macro parameters such as loading stress, cumulative deformation is revealed. The macro-mesoscopic mechanism of dynamic responses for biocemented calcareous sand is clarified. This research will provide basis and reference for improving the seismic prevention of biocemented calcareous sand.