A three-dimensional upper-bound limit analysis of inhomogeneous and reinforced embankment stability

Abstract:

The stability of embankments in regions with heterogeneous soft soils presents a key technical challenge in geotechnical engineering. To enhance the assessment of their three-dimensional (3D) stability, a 3D basal failure mechanism for reinforced embankments on heterogeneous soft soils is developed based on the upper bound limit analysis theorem, and the corresponding energy conservation equation is formulated using the principle of virtual work. A genetic algorithm is introduced to construct an efficient optimization strategy for solving the upper bound solution of 3D stability. The proposed failure mechanism is further degenerated into a 3D toe failure mode of slopes and compared with existing upper bound solutions for slopes, thereby verifying the accuracy and computational efficiency of the genetic algorithm. On this basis, a series of parametric analyses are conducted to investigate the influence of stratification characteristics, unsaturated strength properties, heterogeneous shear strength distribution, tensile strength of reinforcement, number of reinforcement layers, and matric suction on the 3D stability of reinforced embankments. The results indicate that under the 3D basal failure mechanism, a larger ratio of heterogeneity coefficients between the unsaturated subsoil and the embankment significantly improves overall stability. For a fixed reinforcement tensile strength, reducing the reinforcement spacing weakens the stabilizing effect of matric suction. When the number of reinforcement layers remains constant, the stabilizing contribution of reinforcement becomes more pronounced with increasing soil heterogeneity. The proposed 3D stability analysis method offers a reliable computational tool for optimizing reinforcement configurations and supports rational embankment design under complex foundation conditions.