چكيده به لاتين
Many human constructions are done on the ground, inside the soil or by the soil. As access to suitable construction sites decreases, so does the need to use poor soils for infrastructure use. In the field of geotechnical engineering, soil in its natural state, intended for engineering purposes, is usually less than ideal. As a result, some ground improvement methods should be performed to improve its mechanical properties such as shear strength, hydraulic conductivity, compaction, stiffness, etc. Today, biological methods have been studied as an alternative to traditional soil improvement methods and their effect on improving soil mechanical properties has been proven. Bio-cementation is a newly developed branch in geotechnical engineering that improves soil engineering properties by using microbiological activities and necessary materials. One of the most common processes for performing bio-cementation is by induction of bacterial calcite (MICP). In this study, two types of soils with different structures have been studied. For this purpose, Firoozkooh sand has been used as silicate soil and Hormoz sand has been used as carbonate soil. After initial studies and experiments, urea and calcium chloride were used as cementation solution reactants in distilled water. Bacillus pasteuris microorganism was also used to make the bacterial solution. Variable parameters in this study include: ratio of concentration of reactants in cementation solution (ratio of urea concentration to concentration of calcium chloride), bacterial concentration in bacterial solution and processing time and temperature, pH, ratio of cementation solution concentration to bacterial solution concentration, granulation and injection method In this study, Taguchi algorithm and Minitab software were used to design the experiments, the samples were made in CBR and uniaxial molds with a certain density, and after the processing time, CBR and uniaxial tests were performed on the samples. شد. The results of the biological improvement index for both silicate and carbonate sands by MICP method have a significant effect on Increased soil resistance has not improved. The results of SEM test showed the formation of a bond between soil particles, which was created as a bridge between particles and increased soil strength. Also, variable parameters alone as well as the interaction of factors have affected the test results.
