NS-10 Shafts and Ancillary Structures (1990)
Milwaukee, Wisconsin
J.F. Shea Company, Inc.
Two deep shafts and three frozen earth cofferdams were constructed in highly organic silt deposits in the downtown area of Milwaukee, Wisconsin. The unusual geometry of the frozen earth structure created excessively large tensile stresses, exceeding the structural capacity of the frozen soil.
After a complex analysis utilizing a time dependent structural finite element computer program, steel reinforcing was used to augment the tensile capacity of the frozen soil. The high water content organic soils had very low thermal conductivity and high latent heat, which could add to increased time to form the frozen walls.
Additional refrigeration pipes were added to this stratum to balance the progress of the freezing with the quicker freezing sands and gravels. A numeric thermal analysis was used to model the freezing time and proved to be a successful tool in predicting the advance and final thickness of a frozen wall.
Milwaukee, Wisconsin
J.F. Shea Company, Inc.
Two deep shafts and three frozen earth cofferdams were constructed in highly organic silt deposits in the downtown area of Milwaukee, Wisconsin. The unusual geometry of the frozen earth structure created excessively large tensile stresses, exceeding the structural capacity of the frozen soil.
After a complex analysis utilizing a time dependent structural finite element computer program, steel reinforcing was used to augment the tensile capacity of the frozen soil. The high water content organic soils had very low thermal conductivity and high latent heat, which could add to increased time to form the frozen walls.
Additional refrigeration pipes were added to this stratum to balance the progress of the freezing with the quicker freezing sands and gravels. A numeric thermal analysis was used to model the freezing time and proved to be a successful tool in predicting the advance and final thickness of a frozen wall.
