Numerical analysis of mudmat contribution to capacity of piled offshore platforms

Mudmat foundations are traditionally used for the temporary support of steel jacket structures prior to installation of the piled foundation system. The contribution of the mudmats is typically excluded from the analysis of structural response post installation. However, there are ground conditions that lend themselves to inclusion of the mudmats contribution to foundation capacity, particularly in situations where extension of the production life of existing facilities is demanded. Inclusion of the mudmats will have an effect on displacements, structural forces and the dynamic amplification of environmental loads. The response of a piled foundation system, including and excluding a mudmat for a ground profile typical of that found in the North West Shelf of Australia (NWS) was predicted using numerical techniques. The effect of including the mudmat in the analyses is shown to be generally beneficial.