Structural Stability Modeling of Submersible Threshold Micro-Dams under Ultra-Low Hydraulic Head Conditions

Structural stability assessment of compact hydraulic structures operating under ultra-low hydraulic head conditions (<0.5 m) remains insufficiently addressed in current dam engineering literature. Submersible threshold micro-dams (STHMD), characterized by limited structural height, reduced stabilizing moment, and permanent or periodic submergence, require a dedicated mechanical modeling approach distinct from conventional large-dam methodologies. This study develops a structural stability modeling framework for STHMD systems that integrates analytical equilibrium formulations and three-dimensional finite-element simulations. The proposed model unifies hydrostatic thrust, sediment pressure, uplift forces, and foundation reaction within a unified mechanical representation. The study verifies stability by systematically evaluating sliding, overturning, and uplift failure modes in accordance with conventional safety criteria (ICOLD, USBR). Analytical modeling yields safety factors of 12.7 for sliding, 15.8 for overturning, and 10.9 for uplift, while numerical simulations confirm structural rigidity with maximum displacement limited to 0.0139 mm and negligible volumetric strain. The combined analytical–numerical approach provides insight into load-interaction mechanisms and structural response under ultra-low head conditions. The proposed framework clarifies the mechanical behavior of the STHMD at micro-scale dimensions and establishes a reproducible methodology for structural stability modeling of compact hydraulic structures in low-gradient river environments.