Simplified limit analysis of bearing capacity of small-aspect-ratio suction caissons in clay with crust

This study proposes a simplified plastic limit analysis (SPLA) applied to the soil profile with the surficial crust for suction caissons with small aspect ratios. Considering that the calculation results from SPLA commonly used are larger than that from the finite element (FE) method for small aspect ratios, for a characteristic one-layer clay strength profile, an improved expression of the bearing factor derived from numerical simulation is used and corresponding failure mechanisms are adopted to improve the accuracy of the SPLA method particularly for short suction caissons firstly. By incorporating the equivalent depth method, the crust effect is incorporated into the SPLA calculations. To verify the reliability of the proposed SPLA method in clay with crust, the horizontal bearing capacity and optimal loading depth, and normalised H-V envelope under different movement patterns, caisson aspect ratios, and soil profiles are calculated and compared with FE results and experimental data. The results show that SPLA gives good agreement in predictions.

Automated summary

This study proposes a simplified plastic limit analysis (SPLA) to analyze the soil profile with surficial crust for suction caissons with small aspect ratios. The SPLA method is improved by incorporating an improved expression of the bearing factor derived from numerical simulation and corresponding failure mechanisms, particularly for short suction caissons. The crust effect is incorporated into the SPLA calculations through the equivalent depth method. The results show that the proposed SPLA method gives good agreement in predictions with the horizontal bearing capacity and optimal loading depth.