Slope Effect on House Shrink-Swell Movements

The area near Gainesville, Fla. has a shrink-swell prone calcium montmorillonite clay of Miocene age that has damaged many houses. During their engineering investigations of some of these houses; the writers noticed an apparent common tendency for houses over clay and on natural slopes to have experienced vertical movements such that the downslope part of the house has moved down relative to the upslope part, or the upslope up relative to the downslope part, or both. Although other factors often confuse the evidence, this paper also shows that the magnitude of this relative movement increases with the steepness of the orginal slope up to the 16% maximum investigated. The writers hypothesize that this important effect of slope results from the cut fill construction methods often used in Gainesville to accommodate a house to a slope, and from the consequent pattern of modified slope drainage around and under the house.