微生物加固珊瑚粉质砂抗液化机理及本构关系研究

南海岛礁因吹填造地夹含大量粉质珊瑚礁砂，在地震作用下易产生地基液化，从而对岛礁安全带来重大隐患。微生物加固珊瑚粉质砂是一种绿色环保加固方法，可在颗粒间产生生物矿化胶结而提高抗液化性。本项目拟通过弯曲元试验，动三轴试验及振动台模型试验，系统研究微生物加固珊瑚粉质砂的剪切波速特性，动孔压模式、动强度特性及抗液化机理；提出考虑微生物胶结的动孔压方程和动强度方程，并建立考虑微生物胶结的剪切波速特征液化判别方程；在边界面塑性理论和临界状态理论框架下，考虑粉粒含量及微生物胶结对土骨架结构体系的影响，提出微生物加固珊瑚粉质砂塑性本构模型。本项目预期成果将丰富岩土工程绿色加固方法的理论基础，对我国防灾减灾工程及国防战略安全具有重要的实际工程意义。

Coral silty sands are well distributed in the artificial islands of South China sea due to the reclamation by hydraulic filling and susceptibly liquefiable under seismic loading, causing uncertainty in safety evaluation. Bio-cementation is an eco-friendly method for improving the liquefaction resistance of coral silty sands by inducing mineralization cementation among grains. In this project, bender element test, dynamic triaxial test and shaking table test are planned to investigate the developing of shear wave velocity, the excess pore water pressure, the dynamic strength and the liquefaction resistance of bio-cemented coral silty sands. The models for predicting the developing of excess pore water pressure and dynamic strength will be updated and the relationship between shear wave velocity and cyclic resistance ratio CRR for evaluating liquefaction potential of bio-cemented coral silty sands will be established. The constitutive model of bio-cemented coral silty sands, considering the effect of fine content and cementation on soil fabric, will be proposed in the framework of bounding surface plasticity and critical state. This project will expand the ground reinforcement method in geotechnical engineering and be a great of significance in application for disaster prevention and national security.