Slope instability is a significant geotechnical and environmental issue that can lead to erosion, landslides and structural collapse, especially in monsoon affected areas. In this study, the influence of biochar amendment and root reinforcement on soil mechanical behaviour and slope stability was investigated by working with the soils sampled from the erosion-susceptible area in Dinajpur Rubber Dam in northern Bangladesh. Acacia auriculiformis biochar and Napier grass root (Pennisetum purpureum) were applied to the soil at a rate of 5%, 10% and 15% biochar contents combined with a mix of 0.5%, 1% and 2% root content combinations on dry weight basis. Index properties, compaction characteristics, permeability, field density, and direct shear testing in line with ASTM standards formed part of a full laboratory test programme to quantify the impact of treatment. The test results showed that the addition of biochar lowers maximum dry density and increases optimum moisture content. Root treatment greatly improves the shear characteristics parameters and slope stability, and the best effect is that treated with 5-10% biochar and 1-2% root content. In this condition, the factor of safety (FOS) was increased from 1.349 with untreated soil to be 2.294. Biochar at the high addition rate (15%) induced marginal increase for strength, as a result of low level of interparticle bonding and soil–biochar interactions. The results obtained were confirmed by numerical slope stability analysis carried out using the software GeoStudio SLOPE/W, and a much higher factor of safety value was achieved for treated slopes when compared to unsprayed cases. In summary, the joint use of biochar and vegetative root reinforcement is an effective, sustainable, and environmentally friendly method to enhance land mass stability in the erosion-prone region’s collapsing slope.
Hossaın et al. (Fri,) studied this question.