The microbial-induced carbonate precipitation (MICP) technique has been increasingly employed for erosion mitigation and stabilization of sandy slopes. Biocementation can improve the strength and stiffness of unsaturated sand. In this study, the performance of a new biogrouting method (i.e., surface percolation) for sandy slopes under unsaturated conditions was investigated. Model-scale laboratory tests were conducted on MICP-treated coastal slopes to assess the erosion resistance to wave actions. The spatial distribution of
in the biocemented sandy slope was measured, which can reveal the mechanism and characteristics of biocementaion of sandy slopes. Results show that the slope surface experienced no obvious erosion after the implementation of MICP treatment for four cycles. The lowest degree of saturation was observed at the slope crest, and it increased to the highest value at the slope toe. Similarly, the erosion resistance was also doubled from the slope crest to the slope toe due to flow of water/solution in the slope in the downward direction.