Numerical Approach for Estimation of Model Parameters from Robotic Site Investigation Device

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Developing a next-generation robotic site investigation device, ROBOCONE, is a significant step forward for accelerated offshore wind energy installations. This 54mm diameter cylindrical device, when pushed into the ground to the required depth, can probe the soil in the lateral, shear and torsional directions with respect to its axis through three separate modules. The P-Y Module, a crucial part of the device, moves outward perpendicular to the device and records the lateral force-displacement trend. The outputs from the P-Y Module are used to estimate the ground mechanical characteristics. This paper presents a procedure to estimate HS-small (HSS) model parameters from the ROBOCONE P-Y Module response. The initial stiffness calculated from the lateral force-displacement response of the P-Y Module is used as the base parameter. A database of correlations between HSS model parameters and P-Y module initial stiffness is developed. This database is created by simulating P-Y Module movement in PLAXIS-3D using the HS-small model, whose parameters are estimated based on established correlations. A range of HS-small models with relative densities ranging from 25% to 90%, covering loose to highly dense sands, were used for this database. A calibrated layered HSS model was used as a reference for verification of the proposed method. A satisfactory comparison between the pile responses based on known and back-analysed HSS parameters was observed in terms of mudline force and moment versus displacement responses.

5th International Symposium on Frontiers in Offshore Geotechnics (ISFOG2025)

2 - Site characterization, in-situ and laboratory testing, measurement