News

EXPANSIVE SOILS PVR THEORIES VS. CASE HISTORIES
Mark J. Farrow, P.E.1 & Michael D. Roland2

Available methods and theories for determining estimates of Potential Vertical Rise (PVR) are as diverse as the soil conditions underlying the State of Texas. For many years. PVR theory has been a hot topic of debate, research and litigation. Most of the recent research regarding expansive soil theory and PVR determinations seems to be associated with the residential construction industry. Although empirical methods developed for the design of residential foundations may be appropriate for this application, these methods do not necessarily apply to commercial construction where ground supported slabs are constructed in conjunction with pier supported grade beams. This paper presents the results of 20 years of correlations between laboratory swell tests on expansive clay soils and measured PVR values from case histories including construction assessments and distress investigations. This paper also presents a suggested quality control measure that should be used when performing laboratory swell tests and the "fatal flaw" which can otherwise occur that can lead to erroneous interpretations.