颗粒级配对珊瑚砂微生物固化影响研究

对不同颗粒级配的珊瑚砂试样在相同条件下进行了微生物固化试验,研究颗粒对细菌的吸附性、固化体无侧限抗压强度与渗透系数、干密度增量的关系及内部碳酸钙的微观分布,分析颗粒级配及初始孔隙比对固化效果的影响。试验结果表明:低孔隙比试样对细菌的吸附性更好,适中的孔隙比能保证砂颗粒对细菌的吸附性与渗透性达到最优平衡;固化体无侧限抗压强度在1 MPa^3 MPa范围内,应力-应变曲线均为软化型,颗粒错动与薄弱结构面导致阶段性应力峰值的出现;抗压强度随干密度增量的增加而增大,随渗透性增大而减小,孔隙比约为1的级配不良试样固化效果最好;固化后孔隙比高的级配良好试样颗粒间碳酸钙黏结较少,孔隙比低的级配不良试样颗粒表面碳酸钙包裹覆盖更好,颗粒间碳酸钙分布更连续均匀。

Influence of Grain Composition on Coral Sand Bio-cementation

Test of coral sand bio-cementation with different grain composition were performed in the same condition,by measuring the absorbability of bacteria to the sand particle,testing the permeability coefficient,dry density and unconfined compressive strength of solidified coral sand columns,scanning microscopic structure of coral sand,systemic analysis on the influence of grain composition and initial void ratio on bio-cementation effect were conducted in this paper.The test show that specimens with low void ratio can absorb more bacteria,and the absorbability of bacteria and permeability of specimens can be balanced properly in medium void ratio.The value of unconfined compressive strength of specimens is within the range of 1 MPa ～ 3 MPa,all the specimens are strain-softening material,and the weak structural plane and partical dislocation of specimens with different grain composition cause to periodical peak value in stress-strain curves.The compressive strength increases with the increase of dry density increment and the decrease of permeability,the biocementation effect of poorly graded specimens with initial void ratio of 1 are the best.After bio-cementation,less calcium carbonate cemented between particles of specimens with high void ratio,and particles of specimens with low void ratio are almost wholly surrounded by calcium carbonate,the cementation between particles is more continuous and even.