Abstract Manager

The proposed 165 km Northern Road Link (NRL) traverses the Hudson Bay Lowlands, where deep, highly compressible peat deposits, shallow groundwater tables, and strong climate-driven hydrological variability pose significant challenges to roadway design, construction, and long-term performance. In this environment, embankment behavior is intrinsically linked to groundwater dynamics, and conventional road design approaches that rely on static or steady-state groundwater assumptions are insufficient to capture settlement, stability, and resilience under evolving hydroclimatic conditions.

To address these limitations, a coupled hydrogeological–hydromechanical modeling framework is developed to support sustainable roadway and infrastructure design in peat-dominated terrain. Transient groundwater flow is simulated using FEFLOW to represent stratified peat and underlying mineral units, lateral and vertical hydraulic connectivity, and time-varying boundary conditions driven by seasonal recharge, surface water interactions, and regional groundwater fluctuations. Unlike conventional approaches, the framework explicitly resolves the temporal evolution of pore pressures within compressible peat layers, providing a physically based representation of climate- and drainage-driven groundwater behavior. Transient groundwater heads from the flow model are coupled with hydromechanical analysis, whereby changes in pore pressure induce effective stress variations and associated consolidation or expansion of peat deposits. Finite element discretization is refined within deformable strata to resolve vertical deformation gradients, and baseline model behavior and parameter uncertainty are constrained using satellite-based InSAR ground-displacement time series, enabling calibration against observed natural subsidence patterns relevant to linear infrastructure performance.

Embankment deformation and stability are evaluated using Limit Equilibrium Method (LEM) and Finite Element Method (FEM) analyses to assess construction-stage settlement, stability, and long-term performance under representative peatland conditions. The modeling results inform performance-based comparison of alternative construction and ground improvement strategies, including geosynthetic reinforcement, staged construction, vertical drains, flotation embankments, and targeted ground improvement.

Preliminary design outcomes indicate that in lower-compressibility zones with thinner peat and lower groundwater tables, geosynthetic reinforcement and preloading can provide adequate strength gain with manageable settlements. In contrast, highly organic terrain characterized by moderate to thick peat, high groundwater tables, and strong seasonal variability may require vertical drains or other pore pressure management measures. Maintaining natural hydrologic connectivity remains central to design, and reinforced flotation approaches incorporating permeable fills, geogrids, and equalization culverts are adopted where hydrogeological modeling indicates elevated hydraulic gradients.

Application to the NRL demonstrates how integrated hydrogeological–geotechnical modeling supports risk-informed design, construction sequencing, and climate-resilient infrastructure development in sensitive northern peatland environments.