This study aims to optimize geotextile placement depth to enhance subgrade strength and achieve sustainable pavement design. Laboratory tests were conducted to characterize the soil and evaluate the effect of geotextile placement at depths of 3/4D, 1/2D, and 1/4D (where D is the total specimen depth). California bearing ratio (CBR) tests revealed that positioning the geotextile at 0.3D significantly improves subgrade strength, yielding a 78.08% increase in soaked CBR (from 5.84 to 10.4) and a 136.56% improvement in unsoaked conditions (from 3.72 to 8.8). Pavement analysis using IITPAVE software further demonstrated that geotextile placement at 0.3D effectively reduces fatigue and rutting strains, allowing reductions in pavement layer thicknesses-16.67% for bituminous concrete (BC) and dense bituminous macadam (DBM), 38.18% for water bound macadam (WBM), and 25% for granular sub-base (GSB). These optimizations lead to a cost saving of Indian Rupee36,06,610 ($42,430) per kilometer. The findings highlight the practical and economic benefits of placing geotextile at 0.3D depth (150 mm for a 500 mm subgrade), offering improved pavement performance, material savings, and enhanced sustainability. This research benefits pavement engineers, contractors, and transportation agencies by offering a sustainable, cost-efficient design strategy. Additionally, the findings provide a foundation for future research into geosynthetic reinforcement techniques under varying soil conditions, supporting the development of resilient, eco-friendly pavements.

来源平台：INDIAN GEOTECHNICAL JOURNAL