A novel biopolymer-amended bentonite-based capillary barrier: performance evaluation against rainfall-induced landslides

The growing demand for infrastructure in mountainous regions has increased landslide risks, highlighting the need for cost-effective and sustainable countermeasures. This study evaluates the performance of soft capillary barrier system (SCBS) using bentonite slurry (BS) enhanced with biopolymer (bentonite-XG slurry (BXGS)) compared to a field slope under natural drying-wetting cycles. Laboratory crack tests were conducted with 1%–5% biopolymer that identified 3% as optimal for crack reduction in BS for application in slopes. Hysteretic hydraulic properties of BXGS were evaluated to assess moisture dynamics, revealing a two-third reduction in saturated water content and a decrease in the order of 10 − 2 m/s in case of saturated hydraulic conductivity during wetting. The instrumented field prototypes were monitored over a year, and it was observed that the BXGS layer of SCBS reduced moisture infiltration by 30%–45% during wet seasons. A numerical model incorporating measured hysteretic hydraulic data, climate conditions, and infiltration-evaporation models using the 2D Richard's equation effectively validated field moisture variations. Subsequent seepage and stability analyses indicated that the SCBS implementation nearly doubled the factor of safety post-critical rainfall compared to the natural slope, highlighting its effectiveness in mitigating slope failures and enhancing infrastructure resilience in vulnerable regions.