Abstract:In order to improve the availability of bacteria and cementation solution for better solidification effect, the low-pH one-phase method was used to analyze and discuss the effects of two different bacterial grouting strategies, i. e. , multiple injection of low concentration bacteria and single injection of high concentration bacteria, on the solidification efficiency of microbially induced calcite precipitation(MICP)technology. Liquid solution, sand layer filtration and sand column bio-cementation experiment were carried out, and thereafter, three aspects including the calcium carbonate production, the grouting waiting period and the bio-cementation effect were evaluated. The result shows that with the same amount of bacteria used, the calcium carbonate produced by multiple injection of low concentration bacteria(OD=0. 45, activity=3 U/mL)is 3 times more than that produced by the single injection of high concentration bacteria method(OD=3. 6, activity=24 U/mL). When the pH of the all-in-one solution decreases to 4, the low concentration bacteria are not easy to flocculate and can provide a longer grouting period. This also results in a more uniform calcium carbonate distribution. It is found that when the calcium carbonate content is about 13%±1%, the unconfined compressive strength of bio-cementation sand column is about 2. 5 times greater than that treated with single injection of high concentration bacteria.