摘要
In addressing problematic soils,geotechnical engineers employ two key strategies:compatibility and improvement.This study focuses on soft and CL deltaic sediments,and seeks to enhance cementation by investigating microbially-induced calcium carbonate precipitation(MICP).Sporosarcina pasteurii bacteria,together with a cementation solution(urea and calcium-containing salt),were electrokinetically injected into deltaic clay soil from the Telar River in Iran.The initial samples,with a dry unit weight(γ_(d))of 12.75 kN/m^(3),underwent injections in two modes:simultaneous injection of the bacterial and cementation solutions and individual injection in a sequential order.Unconfined compression strength tests and laboratory vane shear tests were conducted to assess changes in soil strength parameters,while a consolidation test was performed to investigate alterations in soil settlement parameters.A comparative analysis with an electroosmosis control sample revealed a remarkable increase in compressive strength and undrained shear strength for MICP bio-electrokinetic improvement.Moreover,the consolidation test demonstrated that the compression index(C_(c))and recompression index(C_(r))exhibited a more pronounced decline in the simultaneous injection than individual injection.This highlights the dual impact of the bio-electrokinetic method,namely the enhancement of shear strength and the mitigation of settlement in deltaic clay soil.The calcium carbonate content was measured for the samples,and the results indicated a higher degree of participation for the samples subjected to simultaneous injection.Microstructure analyses were conducted on samples,and calcite and vaterite were observed in biocemented samples.
