Harnessing Green Cover Systems for Effective Slope Stabilization in Singapore

Slope stability is crucial in civil engineering, especially in urban areas like Singapore, where heavy rainfall may result in catastrophic slope failures. This study aims to evaluate the effectiveness of three rectification methods, i.e., vegetation covers, GeoBarrier Systems (GBS), and Capillary Barrier Systems (CBS), in reducing rainwater infiltration for maintaining slope stability. Numerical analyses were conducted using finite element seepage and limit equilibrium slope stability software incorporating various rainfall and soil conditions to simulate real-world scenarios, focusing on the Factor of Safety (FOS) and Overdesign Factor (ODF) variations during and after rainfall events. The results from numerical analyses indicate that all three rectification methods significantly reduced negative pore pressure across slope layers under different rainfall scenarios, with CBS being slightly less efficient compared to other methods. Compared to simulations of slopes without rectification methods, the negative pore pressures of the rectified slope are improved by 50 kPa, demonstrating the effectiveness of the rectification methods in mitigating rainwater infiltration. The rectification methods showed similar trends in FOS values, with significant improvements over bare slope simulations. The FOS of the bare slope dropped by 0.7, reaching 1.0 under short, intense rainfall and 0.94 under prolonged heavy rainfall. The FOS of the slope with rectification methods remained stable, with only a 0.05 drop under different rainfall scenarios. The ODF showed similar results. Simulations with high-permeability soils revealed the same trends, confirming the rectification methods’ reliability in representing negative pore pressure and FOS accurately. These findings suggest that all three rectification methods are highly effective in maintaining slope stability under heavy rainfall, making them viable options for slope stabilization in Singapore.