Behavior of Wharf Affected by River Fluctuations

Fluctuations of water levels in the Houston Ship Channel caused movements and some structural damage to a pile-supported wharf constructed in overconsolidated plastic Pleistocene clay. During the winter after dredging to deepen the ship channel and again during the next winter, movements occurred when lower than normal water levels were produced by short-duration strong northerly winds. Dredging of the channel initiated a progressive type of soil failure in the high swelling Beaumont clay. The lower than normal water levels caused repeated temporary overstressing and spreading of the failure surface behind the wharf. The initial slide movement occurred when an extreme low water level created sufficient overstress for a long enough period to cause rapid progressive failure. Analyses of the movements revealed that the long-term stability of the wharf built in expansive overconsolidated clay should be based on effective stress parameters significantly less than the peak values. The wharf was successfully renovated without disrupting loading operations of vessels.