Abstract: The silt can be strengthened effectively by the bio-cementation approach, in which the Sporosarcina pasteurii solution was premixed with dry soil followed by cementation solution (including equal ratio of calcium chloride and urea) percolation several times. The amount of reaction solution used (the number of percolation treatments of cementation solution and the volume of bacterial solution) has a significant impact on the reinforcement effect. The test results of cementation solution percolation treatments show that the samples reinforced with different percolation treatments have good stability in water. As the number of infiltration treatments increases, the CaCO3 content and unconfined compressive strength in the sample gradually increase, and the increase in the late percolation stage is higher than that in the early stage. The scanning electron microscope photos indicate that the crystal size of CaCO3 is much bigger when there are more times of cementation solution percolation. The test results of bacteria solution volume show that when the amount of bacterial solution is 1.0 time of the pore volume (1.0Vv), relatively more CaCO3 is generated in the sample, and the unconfined compressive strength is also higher. Reducing the volume of bacterial solution could not improve the reinforcement effect. Besides, when the percolation times is less, the reinforcement of samples treated with 0.6Vv of bacteria solution is poor.

Key words: geotechnical engineering; microbial-cementation; cementation solution; percolation treatments; bacteria solution volume

摘要： 采用先将巴氏芽孢杆菌的菌液与粉土拌合，然后入渗多轮胶结液(包含等比例的氯化钙和尿素)的方法可对粉土进行有效胶结加固。反应溶液用量(胶结液入渗轮数和菌液体积)对加固效果有重要影响。胶结液入渗轮数试验结果表明：不同入渗轮数加固的试样在水中具有良好的稳定性；随着入渗轮数增加，试样中的CaCO3含量和无侧限抗压强度逐渐提高，且入渗后期的增幅高于前期。扫描电镜结果表明：入渗轮数较多时沉积的CaCO3晶体尺寸更大。菌液体积试验结果表明：当菌液用量为1倍孔隙体积(1.0Vv)时，试样中生成的CaCO3相对较多，无侧限抗压强度也更高。减少菌液体积并不能带来加固效果的提升；当入渗轮数较少时，采用0.6Vv菌液体积的加固效果较差。

关键词: 岩土工程；微生物胶结；胶结液；入渗轮数；菌液体积