微生物拌和加固钙质砂渗透特性试验研究

Permeability experiment study of calcareous sand treated by microbially induced carbonate precipitation using mixing methods

吹填钙质砂是岛礁工程中常见的地基土,其所处的海洋环境对其渗透性和抗渗透破坏能力提出一定要求。微生物与钙质砂拌和的方法,有可能将微生物诱导碳酸钙沉积(MICP)技术与吹填工艺结合,以期在吹填过程中完成对地基土的预处理。通过对不同密实度的钙质砂进行微生物固化前后的渗透试验,探究微生物拌和固化方法改善钙质砂渗透性和抗渗透变形性能的效果。结果表明,拌和方法可以使松散钙质砂的渗透系数降低至密实砂同等水平,其抵抗渗透破坏的临界水力坡降也大幅提高,破坏形式由管涌变为流土。

Hydraulic filled calcareous sand is usually used as foundation soil in island projects;and the marine environment surrounding has certain requirements for its permeability properties and seepage failure resistance. By mixing up microbial treatment solution and calcareous sand, microbially induced carbonate precipitation(MICP) technology might be applied to ground improvement through hydraulic progress. Permeability experiments of MICP treated and non-MICP treated calcareous sand with different relative densities are conducted and their permeability properties are evaluated. The results show that the mixing method could reduce the permeability of loose sand to the same level of dense sand;the critical hydraulic gradient increased substantially as well;and the mode of seepage failure changed from piping to flowing soil.