مشخصات پژوهش

The main objective of this researc h is to stud y the effect of microbia l-induced calci te precipi tation on the geotechni cal prope rties of fine-grain ed soils. For this purpose, a high plastic cohes ive soil retrieved from a speci al zone o f Tabriz city, locate d in east Aze rbaijan provi nce in Iran, and two cultur ed Pseudomon as and Bacillu s bacteria with various concentrations wer e added to the soil sam ples, and then com paction and consolidat ed undra ined triaxial tests were perform ed on them. The resu lts of compact ion tests indicated that bacterial treatme nt did not aff ect meanin gfully maxim um dry density of soil, while it reduc ed the optim um moisture o f soil from 30.46% up to 23.83% . More over, bacteria inclusion incr eased shear strength of soil about 27.0% and 35.0% , respective ly, for consoli dation pressure s of 200 kPa and 300 kPa. SEM analysi s reveale d that after treatme nt, the soil particle s arrange in an aggre gative structure with a numb er of small pore spaces and form a few large pore spaces. Th e format ion of the new structu re in treated soil has led to strength improv ement. In general , cal cite partic ipation led to an increas e in shear-indu ced pore water pres sure, which is due to formation of calci te crystals betwee n clay partic les. Obtained resu lts revealed po tential abili ty of these bacteri a in treatme nt of fine-gr ained soils, but it needs mor e researc hes in this field.