Caisson foundations are widely used in offshore geotechnical engineering due to their ability to withstand complex natural and seismic loads, along with environmental factors. During service, caissons experience vertical, horizontal, and moment (V-H-M) loads. This study simulates real-world scenarios, such as wave-induced rapid load changes, by analysing V-H-M loading using three-dimensional finite element analysis (FEA). A literature review on foundations in homogeneous soil under V-H-M loading was conducted to identify research gaps, particularly in failure envelopes. To address this, we extended the analysis to caisson foundations in layered soil, accounting for caisson-soil interface conditions. Numerical models were developed and validated using laboratory prototypes with similar properties and simulated using the finite element software ABAQUS Cae computer program. Variations in the sand relative density were examined for their effects on bearing capacity. Results were presented as normalized and dimensionless failure envelopes in V-H, V-M, and H-M spaces. Comparisons with existing studies confirmed that the proposed numerical methods accurately describe caisson foundation capacity under V-H-M loading in layered soils. The findings contribute to developing standard design codes for offshore caisson foundations, marking a significant contribution to the field.