珊瑚砂微生物固化体三轴压缩声发射试验研究

Triaxial Compression with Acoustic Emission Test of Biocemented Coral Sand

对不同干密度增量的珊瑚砂微生物固化体进行了三轴压缩声发射试验,研究不同围压条件下固化体的应力应变曲线特征及对应的声发射信号特征。试验结果表明,珊瑚砂微生物固化体的三轴压缩声发射曲线可分为三个阶段,在应力应变曲线的近似线弹性阶段声发射活动不频繁,屈服阶段声发射活动频度增大,延性流动阶段声发射活动频度降低,但仍有少量声发射振铃计数与能量高峰出现;累计振铃计数曲线呈直线型,反映了声发射活动在变形全过程均维持了一定的频度,说明内部的胶结断裂与颗粒破碎持续发生,颗粒发生错动并重新排列,导致固化体表现出延性流动特性。通过声发射试验,可以更好地理解珊瑚砂微生物固化体的宏观变形与破坏过程,为建立珊瑚砂微生物固化体损伤本构模型奠定基础。

To explore the characteristics of stress-strain curves and corresponding curves of acoustic emission signal,triaxial compression with acoustic emission test under different confining pressure of biocemented coral sand with different dry density was conducted.The test results shown that,curves of acoustic emission signal under triaxial compression could be divided into three stages,the acoustic emission activity was not heavy in approximate linear stage,and it increased in yield stage,then decreased in ductile flow stage while still show some peak values of CNT and ENE.The cumulative CNT curves were linear type,which reflects that the acoustic emission activities were persistent during deformation process.As the biocementation fracture and particle breakage occurring continuously,the particle moved and repacked,thus the specimens showed ductile flow property.The macroscopic deformation and failure process of biocemented coral sand can be better understand by triaxial compression with acoustic emission test.The test results lay a foundation for the establishment of damage constitutive model of biocemented coral sand.