中文摘要：

通过直剪试验，研究培养液类型、浓度和培养时间3因素变化时，微生物对粉土抗剪强度的影响．通过向土体中注入不同浓度的葡萄糖和淀粉溶液，对土体进行15、30和60d的培养．制作环刀试样，进行直剪试验．分析发现，淀粉溶液和葡萄糖溶液培养的微生物均能显著提高粉土的抗剪强度；相同培养时间下，培养液浓度增大，粘聚力和内摩擦角呈增大趋势；用葡萄糖和淀粉溶液培养60d后，粉土的粘聚力提高2．38和2．03倍，内摩擦角扩大了6．54和8．40倍．实验结果可为微生物改性土工程提供参考．

英文摘要：

In this paper, direct shear test is conducted to investigate the effect of microbes on the shear strength of silty soil under the conditions with varying culture medium, culture medium concentration and culture time. By injecting different concentrations of glucose and starch solution into the soil, observations after 15 days, 30 days and 60 days of culture are carried out, respectively. As can be seen from direct shear tests, both glucose and starch solution can improve the shear strength of silty soil. Both cohesion and internal friction angle of silty soil show increasing trend along with increasing concentration of culture medium at the same culture time. After cultured by glucose and starch solution for 60 days, the cohesion of silty soil can increase to 2.38 and 2.03 times respectively, and the internal friction angel of silty soil can increase to 6.54 and 8.4 times respectively. The results are expected to provide reference for soil improvement by microbes.