一株本源产脲酶细菌的分离培养及其在裂隙岩体加固中的应用

Isolation and culture of a native urease-producing bacterium and its application in the reinforcement of fractured rock mass

微生物诱导碳酸盐沉淀是岩土工程领域一种新型绿色环保加固技术,为了研究工程环境中原位提取产脲酶细菌的加固效果,从三峡库区典型岸坡土体中分离提取了一种高效产脲酶菌种,经鉴定为蜡样芽孢杆菌。为了分析其加固效果,首先通过正交优化确定了蜡样芽孢杆菌的最佳培养条件,然后采用蜡样芽孢杆菌和巴氏芽孢杆菌进行了砂柱和裂隙岩体固化试验。结果表明:(1)相比于巴氏芽孢杆菌,蜡样芽孢杆菌固化的砂柱孔隙的填充更为密实,抗渗性更好,碳酸钙生成量更高,说明蜡样芽孢杆菌具有较好的成矿作用;(2)蜡样芽孢杆菌加固后裂隙岩样的渗透系数降低了3个数量级,内摩擦角和黏聚力分别增加了48.09%、85.10%,说明蜡样芽孢杆菌可有效改善裂隙岩体的渗透性能和抗剪性能,而且相比巴氏芽孢杆菌具有更好的加固效果。相关研究思路和结果可为工程岩体绿色加固提供较好参考。

Microbial-induced carbonate precipitation is a novel green reinforcement technology in the geotechnical engineering field.To study the reinforcement effect of urease-producing bacteria extracted from the engineering environment in situ, a highly effective urease-producing bacteria was isolated from typical bank slope soil on the Three Gorges Reservoir and identified as Bacillus cereus. To analyze the reinforcement effect, the optimum culture conditions of Bacillus cereus were first determined by orthogonal optimization,and then the solidification tests on a sand column and fractured rock mass were carried out using Bacillus cereus and Sporosarcina pasteurii. The results showed that:(1) Compared with Sporosarcina pasteurii, the porosity of the sand column reinforced by Bacillus cereus was filled more densely, the impermeability was better, and the calcium carbonate engenderment was higher, thus designating that Bacillus cereus had better mineralization function.(2) The permeability coefficient of fractured rock samples reinforced by Bacillus cereus decreased by 3 orders of magnitude, and the internal friction angle and cohesion increased by 48.09% and 85.10% respectively,denoting that Bacillus cereus can efficaciously ameliorate the permeability and shear resistance of fractured rock, and compared with Sporosarcina pasteurii, it has a better reinforcement effect. Relevant research conceptions and results can provide a good reference for the green reinforcement of engineering rock mass.