珊瑚砂微生物固化体三轴压缩试验及损伤本构模型研究

利用微生物诱导碳酸钙沉积（MICP）技术固化南海某岛礁的陆域吹填珊瑚砂，对珊瑚砂微生物固化体进行了三轴压缩试验，基于损伤力学理论建立了珊瑚砂微生物固化体的损伤本构模型。结果表明，利用MICP技术固化珊瑚砂效果好，强度高；固化体的三轴压缩应力–应变曲线可分为近似线弹性阶段、屈服阶段与延性流动阶段。将固化体划分为匀质微元进行损伤演化分析，根据连续介质损伤力学的有效应力理论与应变等效假说，定义了损伤变量，假定固化体强度服从双参数的Weibull分布及Druker-Prager准则，建立了损伤本构模型。模型参数包括固化体力学参数和Weibull分布参数，由三轴试验和线性回归法确定，并用试验资料初步验证了模型的合理性。

Study of triaxial compression test and damage constitutive model of biocemented coral sand columns

Coral sand of land reclamation in island of South China Sea are biocemented by microbially induced carbonate precipitation(MICP) method; triaxial compression tests of biocemented coral sand columns are conducted; the test results are analyzed; and the damage constitutive model of biocemented coral sand columns is proposed based on the theory of rock damage mechanics. The test and analysis results show that, coral sand can be biocemented well by MICP method; and the stress-strain curves of biocemented columns can be divided into approximate linear stage, yield stage and ductile flow stage. Biocemented columns are divided into homogeneous unit cell, damage evolution analyses are conducted and damage variable is defined based on the theory of effective stress and hypothesis of strain equivalence; and damage constitutive model is proposed with the assumption that the strength of biocemented columns obey the Weibull distribution and Druker-Prager criterion. The model parameters including mechanical parameters and Weibull distribution parameters, which are defined based on tests data and calculated by linear regression method. The rationality of model is preliminarily verified by tests data.