Assessment and Mitigation of Cavity Induced Sinkhole Effects on Shallow Foundations Using FELA and Machine Learning
摘要
This study investigates the ultimate bearing capacity (UBC) of shallow foundations resting above single and dual subsurface cavities in cohesive–frictional soils. Adaptive Finite Element Limit Analysis (AFELA) is employed for the numerical investigation. The soil behaviour is characterized using the Mohr–Coulomb criterion, and the influence of shear strength parameters (c′, ϕ′), the unit-weight factor (γB/c′), and cavity geometry expressed through normalized offset (M/B), depth (N/B), and spacing between dual cavity (S/B) is assessed through the stability number (Ns). The proximity of the cavity is shown to markedly reduce Ns, with the most critical condition occurring at M/B = 0. The adverse influence diminishes progressively and becomes negligible beyond M/B = 3–4.5 and N/B = 3.5–4.5, depending on soil friction, indicating reduced vulnerability to void-induced settlements and sinkhole-type geohazards at greater embedment depths. The parameter γB/c′ significantly governs the stability response. Low γB/c′ values (γB/c′ = 0.5–1.0) produce stable and convergent solutions, whereas high γB/c′ values (γB/c′ = 2) leads to non-convergence in low-ϕ′ soils due to self-weight-controlled failure. For dual cavities, significant interaction occurs for S/B < 2, whereas stability is restored when the spacing increases to S/B ≥ 3. Higher friction soils (ϕ′ = 15°–20°) consistently exhibit enhanced Ns and reduced sensitivity to cavity location, whereas low-ϕ′ geomaterials remain susceptible to instability under natural hazard scenarios such as rainfall softening, subsidence, or seismic disturbances. Machine-learning evaluation based on the FELA dataset confirms the superior predictive performance of nonlinear models, particularly ANN and GPR, achieving R2 > 0.99.