海水环境下巴氏芽孢杆菌驯化及钙质砂固化效果研究

为了提升微生物诱导碳酸盐沉淀(MICP)技术在海洋环境下对钙质砂的加固效果,在以往研究的基础上,设计进行了人工海水环境下巴氏芽孢杆菌多梯度人工驯化培养试验,并结合MICP固化钙质砂柱的力学试验和微细观结构分析,对巴氏芽孢杆菌的驯化效果进行了综合评价。结果表明:(1)海水环境下五梯度驯化后细菌的菌液浓度可达到淡水环境的97%以上,其与胶结液作用后碳酸盐的生成量较淡水环境下有一定幅度提高;(2)驯化后的巴氏芽孢杆菌具有很好的温度适应能力,在10～30℃温度下均有较好的MICP性能;(3)海水环境下加固的钙质砂柱无论是碳酸盐生成量还是无侧限抗压强度均较未驯化前高,尤其是五梯度驯化后的细菌,驯化后的细菌菌体变小,在海水环境生成的碳酸盐(碳酸钙和碳酸镁)晶体更小,更加致密,能更好地填充钙质砂颗粒的孔隙并胶结相邻的钙质砂颗粒,具有更优异的MICP性能。相关研究思路和方法可为MICP技术在海洋环境钙质砂地基加固方面的研究与应用提供参考。

Study on the domestication of Sporosarcina pasteurii and strengthening effect of calcareous sand in seawater environment

In order to improve the strengthening effect of microbially induced carbonate precipitation(MICP) technology on calcareous sand in the marine environment, on the basis of previous studies, the multi-gradient artificial domestication culture test of Sporosarcina pasteurii in artificial seawater environment was designed and carried out. Combined with the mechanical test and micro-mesostructural analysis of MICP strengthened calcareous sand column, the domestication effect of Sporosarcina pasteurii was comprehensively evaluated. The results showed that: i) The bacterial liquid concentration after five-gradient domestication in seawater environment could reach more than 97% of that in freshwater environment, and the production of carbonate after the interaction with cementing fluid was increased to a certain extent compared with that in freshwater environment. ii) The domesticated Sporosarcina pasteurii had good temperature adaptability, and it had good MICP performance at 10 ℃ to 30 ℃. iii) Both carbonate production and unconfined compressive strength of calcareous sand columns strengthened in seawater environment were higher than those before domestication, especially the bacteria after five-gradient domestication, and the bacteria after domestication became smaller. The carbonate crystals(calcium carbonate and magnesium carbonate) generated in the seawater environment were smaller and denser, which could better fill the pores of calcareous sand particles and cement the adjacent calcareous sand particles, and had better MICP performance. The relevant research ideas and methods can provide reference for the research and application of MICP technology in the reinforcement of calcareous sand foundation in seawater environment.