The Laurel at Rittenhouse Square,
Philadelphia, Pennsylvania

Test borings including rock coring were conducted to characterize the subsurface conditions for foundation and construction. A mat foundation was selected as the optimal foundation system with estimated savings of over $2 million versus caissons. A detailed evaluation was carried out by GeoStructures to minimize the impact on the surrounding historic structures. GeoStructures performed pressuremeter testing (PMT) to accurately determine the elastic moduli of the foundation soils. The results were incorporated into a Finite Element Method (FEM) model for mat and underlying soil— both vertically and laterally. The construction sequence for the mat was simulated during the analysis including viable stages. The test results were used to determine settlement of the mat under the tower and its impact on adjacent structures, especially the immediately adjoining Theosophy Building.