[Objective] Microbially induced carbonate precipitation (MICP) method is a potentially effective and environmentally friendly technique to improve the unfavorable soil conditions. MICP treatment can improve soil strength. However, the durability of MICP-treated soil under freeze-thaw cycles has not been investigated. [Methods] This study investigates the effects of freeze-thaw cycles on unconfined compressive strength, erosion resistance, and water retention capacity of soil which treated with MICP under different conditions. The surface of the specimens was treated using the spray method, and then some specimens were subjected to erosion tests. Unconfined compressive strength (UCS) and water evaporation rate of the specimens under different freeze-thaw cycles were tested. Combining the mechanism of soil resistance to erosion damage and the test results of specimens under freeze-thaw cycles, the reasons for the deterioration of reinforced soil properties due to freeze-thaw cycles are investigated. [Results] The results show that the UCS of the sample has increased from 43.83kPa to 69.92kPa after MICP-treated. After 20 freeze-thaw cycles, the UCS of the MICP-treated sample is 1.48 times that of the uncured sample, and the erosion amount of the MICP-treated sample is much less than half of that of the uncured sample. The results indicate that the microbially induced calcium carbonate deposits can effectively fill the internal pores of the soil and bind the loose soil particles, thus significantly improving the soil strength and effectively weakening the damaging effect of freeze-thaw on the soil. [Conclusion] Although the consolidation effect of the soil gradually deteriorated due to the increase of the freeze-thaw cycle, the MICP-treated soil still had high strength under the short-term freeze-thaw environment and could effectively resist the erosion effect of rainwater.
DownLoad: