# Experimental Study of Erosion Prevention Model by Bio-Cement Sand
## 4 Conclusions  
Traditional slope protection materials for embankment dams include concrete and cement slurry, gabion nets, and vegetation-based solutions. Among these options, concrete and cement slurry offer exceptional stability and durability; however, they have a significant environmental impact, along with potentially higher construction costs and time requirements. Gabion nets are effective for river management but tend to appear less natural, with the added concern of metal corrosion over time. In contrast, vegetation slope protection is environmentally friendly but necessitates time for establishment and may lack sufficient stability under extreme erosion conditions. Microbial grouting presents an innovative approach by rapidly forming a stable calcium layer while being environmentally sustainable. However, this technology remains in its developmental phase, characterized by limited case studies and standards. The complexity and uncertainty associated with  
Figure 11: The evolution process of scour morphology was tested by flume model, (**a**) reinforced 3 times, (**b**) reinforced 6 times. its implementation are relatively high. Additionally, the long-term stability of microbial growing may not match that of traditional cement grouting; furthermore, its effectiveness can be influenced by environmental factors such as temperature and pH levels--conditions that could adversely affect consolidation outcomes in certain scenarios. This study leverages the fundamental principles of microbially induced mineralization to conduct model tests aimed at assessing seepage and erosion mitigation in soil slopes reinforced through grouting for indoor earth dams. It systematically investigates slurry diffusion patterns, migration dynamics, and cementation characteristics pertinent to soil dam grouting while evaluating the penetration strength and erosion resistance properties of sandy slopes subjected to microbial spraying across varying reinforcement levels. The application of microbial spraying on sandy soil slopes effectively binds sand particles, resulting in a durable white shell formation on the surface that markedly enhances penetration strength. A direct correlation was established: as reinforcement intensity increased, so too did penetration strength. Moreover, both cementation depth and penetration strength demonstrated a positive correlation with calcium carbonate content. An analysis of penetration resistance at various measurement points revealed an uneven distribution of sand particles during stacking; this variability, compounded by difficulties in achieving uniform slurry application via a manual watering can, resulted in significant non-uniformity in slope strength--characterized by elevated strengths at peripheral regions contrasted with diminished strengths centrally. Furthermore, microbial spraying treatment significantly improved cohesion among sand particles, thereby enhancing the anti-erosion performance of slope soils. The relationship between shear stress and slope erosion is primarily governed by gravitational forces and particle adhesion mechanisms. Erosion shear stress for unconsolidated sands reaches its initiation threshold under hydrodynamic influence; concurrently, erosion rates increase proportionally with bed shear stress, initially exhibiting gradual growth followed by rapid escalation--a trend consistent with power function behavior overall. Microbial grouting promotes the consolidation of smaller soil particles into larger aggregates; these well-consolidated structures substantially enhance surface erosion resistance while mitigating gully formation risks. Enhanced reinforcement correlates positively with superior erosion resistance outcomes. The primary cause of dam slope failures is the inadequate bonding strength between soil particles, which hinders their ability to withstand the shear forces exerted by water flow. Consequently, enhancing the bonding strength among soil particles is a crucial strategy for improving erosion resistance and preventing soil erosion and loss.