Geotextiles are commercially made from synthetic fibres and have been used to enhance bearing capacity and to reduce the settlement of weak soil foundations. Several efforts have been made to investigate the possibility of using bio-based geotextiles for addressing environmental issues. This paper attempts to review previous studies on the bearing capacity improvement of soils reinforced with bio-based geotextiles under a vertical static load. The bearing capacity of the unreinforced foundation was used as a reference to illustrate the role of bio-based geotextiles in bearing capacity improvement. The effects of first geotextile depth to footing width ratio (d/B), geotextile spacing to footing width ratio (S/B), geotextile length to footing width ratio (L/B) and the number of reinforcement layers (N) on the bearing capacity were reviewed and presented in this paper. The optimum d/B ratio, which resulted in the maximum ultimate bearing capacity, was found to be in the range of 0.25–0.4. The optimum S/B ratio was in the range of 0.12–0.5. The most suitable L/B ratio, which resulted in better soil performance against vertical pressure, was about 3. Besides, the optimum number of layers providing the maximum bearing capacity was about three This article is useful as a guideline for a practical design and future research on the application of the natural geotextiles to improve the short-term bearing capacity of weak soil foundations in various sustainable geotechnical applications.

Lateritic soil is a kind of residual soil widespread in tropical countries. This soil usually possesses acceptable engineering properties to be laid under the construction projects. However, it needs treatment for transportation infrastructure such as railway and road subgrade and embankment, particularly when it is in fine-grained form. Thus, cement, one of the very common stabiliser agents in soil stabilisation, was selected to study its influence on lateritic soil at macro- and micro-levels. In order to achieve this goal, UCS, durability, FESEM and EDX tests were conducted. The results obtained indicate that the UCS increase occurs with an increase in cement content and curing time. It was also found that the shear modulus increases with cement content and curing time. The durability test results disclosed that 3% cement is not enough for soil stabilisation when used for projects in the areas subjected to cyclic wetting-drying cycles. The durability test results revealed that the UCS decreased for specimens treated with 6% cement, while on the other hand, the UCS increased for samples treated with 9% and 12% cement. The FESEM results revealed that the soil micro-structure changed with the addition of cement and curing time. The EDX results presented the chemical elements change upon adding cement and increasing curing time. Overall, it was found that cement-stabilised residual soil can be used for road construction. However, the cement percentage needed to stabilise residual soil differs depending on the standards.

This paper concerns the adequacy of utilising a chimney drain, horizontal filter and cutoff wall in reducing seepage through an earthen dam. To this end, anti-seepage systems comprising a chimney drain, a horizontal filter and a cutoff wall were investigated. Variations of lengths, angles and locations of these features were studied. The amount of seepage was determined using SEEP/W software. The results indicated that by expanding the vertical chimney drain and the horizontal filter from the embankment toe to half or three-quarters of the downstream slope, the seepage flow from the dam body and its foundation will decrease. On the contrary, when the horizontal filter's length is extended to more than three-quarters of the dam's downstream slope, the amount of seepage flow that may pass through the dam's cross-section rapidly increases. Additionally, it was observed that seepage from the earthen dam and its foundation reduced by increasing the cutoff depth. Finally, with respect to the minimum factor of safety for the downstream slope, obtained using SLOPE/W software, a suitable model for seepage control within the body and foundation of the dam was found to be the hybrid model introduced at the end of this study.