Analytical and numerical studies on the scouring of a pile foundation of a marine terminal

Introduction. The purpose of the work is to assess potential scouring of the bottom soil of a designed marine terminal resting on a pile foundation to prevent the bottom erosion caused by wind waves and currents. Materials and methods. The authors have analyzed those effective regulatory documents that could be potentially used to study erosion near pile foundations of marine terminal structures. Numerical modelling of lithodynamic processes was conducted in the mooring basin area in extreme weather conditions, like severe storms, to study soil erosion near the hydraulic structures of the marine terminal. Results. Having analyzed the method used to assess local erosion pursuant to VSP 33-03-07 (Industry-wide set of rules 33-03-07), the authors concluded that it had major fundamental drawbacks and, therefore, it could not be applied to a multi-row pile structure. Therefore, it could not guarantee the required accuracy of projections. The authors presented the numerical modelling of wind waves, currents and lithodynamic processes to study the wave erosion on the bottom of the mooring basin of the marine terminal. Towards this end, a three-level system of interconnected models was designed. It had a model of wind waves, a model of currents and changes in sea levels and a lithodynamic model. Conclusions. Having considered a method for assessing local erosion, described in VSP 33-03-07 (Industry-wide set of rules 33-03-07), engineering and geological conditions near the NZMU marine terminal, as well as the structural solutions contributed to the project, the authors believe that this method cannot be applied to reliably analyze local erosion near the pile supports of a sea terminal. Simulated lithodynamic processes, that are underway near the pile supports of designed mooring structures, suggest that anticipated erosion, caused by severe storms, did not exceed 25 cm and no complete erosion funnel was formed around the pile. Sediment accumulation zones appeared on the windward side of the piles. They were larger than the zones of erosion. Therefore, the authors assume that the influence of lithodynamic processes on the stability of pile supports is insignificant during the operation of hydraulic structures of the marine terminal.