Abstract: 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.

Key words: coral sand, biocemented columns, stress-strain curves, Weibull distribution, damage constitutive model