Pioneer performed a geotechnical investigation for a proposed 5-story building in order to determine subsoil conditions at the site. The site generally consisted of medium dense, saturated sand to a depth of approximately 22 feet below existing grade, followed by soft to stiff silty clay to a depth of approximately 35 feet below grade. The investigation included the performance of Standard Penetration Tests (SPT) in the sand stratum and insitu vane shear tests in the soft clay. Laboratory consolidation tests were also performed on shelby tube samples extracted from the soft clay layer.
Pioneer performed advanced settlement analyses using UniSettle software, where the proposed foundation layout along with relevant line and column loads and floor loads were simultaneously simulated to determine the resulting differential settlements. After various iterations it was determined that a conventional spread footing system could be utilized with acceptable differential settlements, thus saving the cost associated with the originally proposed deep foundation system at this challenging site.