Abstract
This research introduces the development of a sequential limit analysis (SLA) method in OPTUM. The plane-strain analysis capability of the original SLA has been extended to encompass both plane-strain and axis-symmetric problems, and the usability has been expanded to a broader spectrum of users. Moreover, refinements in addressing nodal velocities during soil collapse under gravity, specifically in scenarios featuring a stiff soil berm leading to slope instability, have been implemented, to enable proper modelling of more extreme conditions and complex model geometries. A detailed validation has been made against various penetration problems. It is revealed that SLA simulations can be executed with displacement increments at the order of 1% of the characteristic size of the object. In addition, a succinct parametric study on ball penetration is presented. Penetration resistance with strain softening is reduced by up to 34.5% compared to the non-softening case. An equivalent plastic strain factor was adopted to enhance the accuracy of measuring soil strength through ball penetrometer tests. The enhanced SLA method could also serve as a powerful tool for analysing large deformation soil-structure interaction problems for piles, spudcans, and cone / ball penetrometers in offshore engineering.