Bio-stimulated sealing technology is an interesting and promising technology for leakage repair in geotechnical engineering.Advancing studies of this technology have shown that some nutrients can be used to activate the metabolic process of in-situ soil microorganisms that induce bio-mediated sealing in a relatively short time.In this paper,we injected nutrient solution into sand columns with leakage and investigated the sealing mechanism.Two sand columns,each with a 2-cm diameter hole,were set up.One was treated with nutrient solution and the other received no nutrients as a control.The results showed that 900 mL of nutrient solution per day,with a concentration of 4.4 g L-1 potato extract solution,could notably decrease the volume of groundwater seepage.Finally,the volume of the seepage in the treated column was 0.85% of the control column.Evidence of micro morphological changes to the sand samples after the bio-stimulated sealing tests is given using the ESEM observations.Chemical element composition,organic and iron compound analyses were performed for an enhanced understanding of the underlying bio-stimulated sealing mechanism.The preliminary results obtained indicate that iron compound deposits,and organics(biomass and biofilm) produced during the sealing process near the leakage enhanced the sealing effect.
