Consolidation of unstable slopes through the use of organic polymers

This thesis investigates the use of anionic polyacrylamide (PAM) polymer as a sustainable solution for improving soil stability and mitigating shallow slope instabilities, such as erosion and landslides. Laboratory experiments were conducted on four different soil types (kaolin clay, silty sand, clay soil, and clayey silt) to assess the impact of varying PAM concentrations (0% to 1%) on soil physical, mechanical, and hydrological properties. Tests focused on Atterberg limits, shear strength, and the record of soil water retention curves. Results were analysed using statistical methods (Pearson’s correlation coefficient r and ANOVA) to quantify the association between specific soil parameters and applied PAM percentage. Results showed that PAM significantly enhances soil cohesion, particularly at concentrations around 0.03%, while simultaneously causing changes in plasticity. PAM-treated soils demonstrated improved water retention capacity and greater resistance to shear forces, particularly under high saturated conditions. The changes in these properties directly influenced slope stability, as highlighted by a sensitivity analysis of Factor of safety (Fs) done using Lu and Godt (2008)’s model to assess polymer's potential to stabilize slopes in various slope angles and pore water pressure scenarios. Its application offers a promising method for mitigating soil erosion, stabilizing agricultural slopes, and reducing shallow instability risk in vulnerable areas. However, the research also emphasized the importance of assessing PAM's long-term environmental interactions and effectiveness under field conditions to ensure its viability as a widespread soil stabilization tool.