COMMITTEE CHAIR: Dr. Md. Jobair Bin Alam
TITLE: HYDROLOGIC PERFORMANCE EVALUATION OF GEOGRID-GEOTEXTILES INTEGRATED EXPANSIVE CLAYEY SLOPES
ABSTRACT: Expansive clay embankment slopes are highly vulnerable to climate-driven wetting-drying cycles, which reduce matric suction and shear strength, leading to surficial failures. While conventional stabilization often focuses on mechanical reinforcement, a significant research gap exists regarding the dual hydraulic-mechanical performance of geosynthetics, particularly geogrid-integrated geotextiles, under field-scale climatic conditions and transient soil-water characteristic curve (SWCC) responses. This study addresses this gap through a quantitative evaluation of geocomposite-reinforced slopes in high-plasticity clay (CH, PI = 47.7-51.2) under natural seasonal exposure. Two field-scale test slopes (1.83 m × 1.07 m × 1.22 m) with 1H:1V geometry were constructed at Prairie View A&M University. One slope featured three horizontal layers of geogrid-embedded geotextile geocomposite, while the other served as an unreinforced control. Using TEROS 11 and 21 sensors, volumetric moisture content (VMC) and matric suction were monitored at depths of 0.5, 1.5, 2.5, and 3.5 ft at 15-minute intervals from June 2025 to February 2026. The resulting dataset was analyzed using descriptive statistics, ECDF, KDE, rank-based Empirical Copula analysis (Kendall’s Tau), and depth-wise Van Genuchten SWCC fitting. The results demonstrate that the geocomposite-reinforced slope effectively moderated moisture dynamics, significantly narrowing the moisture envelope compared to the control. During the summer, mean VMC at the 1.5 ft depth increased from 0.285 to 0.332, while the coefficient of variation (CV) decreased from 0.046 to 0.028, indicating enhanced hydraulic stability. Similar buffering effects were observed during winter. ECDF and KDE analyses confirmed tighter moisture distributions in the reinforced slope, while Copula analysis revealed stronger depth-integrated hydraulic connectivity. Furthermore, SWCC fitting showed modified suction-moisture behavior, particularly at intermediate depths. These findings confirm that geogrid-integrated geotextiles function as both hydraulic buffers and mechanical reinforcement. This probabilistic framework provides a robust basis for reliability-oriented assessments of expansive soil embankments subjected to seasonal moisture uncertainty and extreme weather.
Keywords: Geocomposite-reinforced Slopes; Expansive Soils; Climate-resilient Infrastructure; Hydro-geotechnical Stability; Soil Moisture Dynamics; Probabilistic Analysis; Unsaturated Soil Mechanic
Room Location: Wilson Building, Room 203