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Title: Innovative Retrofit of a Steam Turbine Generator Foundation to Mitigate Settlement

Author(s): Hongchun Liu, Jaspal S. Saini, Gang Zhao, Sushil Chauhan, Namgyu Park, Mahi Galagoda, Steven Wu

Publication: Symposium Paper

Volume: 348


Appears on pages(s): 19-34

Keywords: steam turbine generator foundation, foundation retrofit, foundation settlement, piles, dynamic analysis, frequency-dependent dynamic impedances, soil impedances, pile impedances.

DOI: 10.14359/51732677

Date: 3/1/2021

This paper discusses an innovative retrofit that stabilized a Steam Turbine Generator (STG) pedestal foundation undergoing unexpected differential settlements during construction. The innovative solution involved driving steel H-piles around the STG foundation perimeter. A new concrete bracket (a.k.a. corbel) was added around the STG foundation perimeter to fully engage and integrate the H-piles with the existing pedestal foundation. The pile layout was established and optimized based on dynamic and static performance analyses of the modified foundation geometry using finite element (FE) software ANSYS, considering bounding pile and soil dynamic impedances. The frequency-dependent dynamic pile impedances were calculated using DYNA6. The continuous settlement monitoring of the STG foundation demonstrated that the retrofit effectively seized the ongoing settlements and stabilized the foundation enabling the subsequent machine installation.