Research on the plastic radius of pile penetration in CPT clayey seabed

Offshore jackups are frequently employed for well workover or maintenance operations, necessitating repeated usage at the same location. Precisely defining the radius of the soil's plastic zone during pile penetration offers a theoretical foundation for establishing the minimum pile spacing required for subsequent well workover or maintenance activities. This study examines the radius of the plastic zone in the seabed of silty soil in the offshore region of the Yellow River Delta and the bearing capacity at various pile diameters following pile penetration, utilizing the Cone Penetration Test (CPT). The specific conclusions are as follows: (1) The disturbance radius of pile penetration into seabed silty soil ranges from approximately 2D to 3D; (2) Utilizing the pile bearing capacity calculation method proposed by Eslami and Fellenius, it is determined that the bearing capacity at a distance of 2.66D from the pile core is equivalent to the initial penetration bearing capacity; (3) According to the Mohr-Coulomb yield criterion theory, the plastic radius of pile penetration in seabed silty soil is calculated to be between 2.4D and 3.2D; (4) The disturbance radius derived from fitting the optimal bearing capacity curve aligns with the minimum pile spacing calculated according to the Mohr-Coulomb yield criterion theory, thereby confirming that the CPT test can accurately estimate the plastic radius of pile penetration.