珊瑚砂微生物固化体单轴损伤本构模型

Damage Constitutive Model of Biocemented Coral Sand Columns under Unconfined Compression

利用MICP技术固化南海某岛礁吹填珊瑚砂,对固化体试样进行了单轴抗压强度试验,基于损伤力学理论建立了单轴压缩条件下的固化体损伤本构模型。结果表明:利用MICP技术得到的珊瑚砂微生物固化体无侧限抗压强度均大于5 MPa,固化体单轴受压应力-应变曲线可大致分为压密阶段、弹性阶段、塑性阶段与破坏软化阶段。基于连续介质损伤力学理论,假定固化体微元强度服从双参数的Weibull分布,考虑应力-应变曲线特征进行参数简化后建立了单轴压缩条件下的损伤本构模型;模型采用经验拟合方程与损伤本构方程结合的分段函数形式,用试验资料初步验证了模型的合理性。

Coral sand in island of South China Sea were biocemented by MICP method,unconfined compression tests of biocemented coral sand columns were conducted,and the damage constitutive model of biocemented coral sand columns under unconfined compression was proposed based on the theory of rock damage mechanics. The test and analysis results show that all unconfined compression strength of biocemented coral sand columns are more than 5 MPa,and the stress-strain curves of biocemented columns could be divided into approximate the compaction stage,elastic stage,plastic stage,failure and softening stage. Basing the theory of continuum damage mechanics and the assumption that the micro-unit strength of biocemented column obey Weibull distribution,the damage constitutive model under unconfined compression was established,and considering the characteristics of stress-strain curves. The model expression is piecewise function that made of empirical equation and damage constitutive equation. The rationality of model was preliminarily verified by tests data.