MICROPILES USED FOR DEEP FOUNDATION SUPPORT AT THE RITA LIDDY HOLLINGS SCIENCE CENTER AT THE COLLEGE OF CHARLESTON, CHARLESTON, SOUTH CAROLINA-Paper

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The Rita Liddy Hollings Science Center project at the College of Charleston combined renovation of a 1960s building with new construction and a major vertical expansion. The existing foundation needed upgrading to meet increased axial and lateral loads and current building codes. Charleston’s lack of bedrock, liquefaction risk, and seismic and hurricane loads require deep foundations bearing in the non-liquefiable Cooper River Marl.<br /><br />Driven piles were ruled out because their noise and vibration would disrupt classes and potentially damage nearby historic unreinforced masonry buildings. The original design specified micropiles beneath the existing structure and auger-cast piles for the new construction. Because the campus site was extremely confined, handling auger-cast equipment and disposing of excavated soil would be difficult. The contractor therefore proposed micropiles for both phases, a solution that proved less costly and suitable for the required axial and lateral loads.<br /><br />Seven test piles underwent axial compression, tension, and lateral load testing. The results supported acceptance of the micropile design. Ultimately, approximately 300 micropiles were installed: larger, cased piles outside the existing building and smaller, uncased piles inside, extending 75–80 feet to the marl.<br /><br />The installation was completed on time and without change orders, despite tight working conditions and a complex construction sequence. Low noise and vibration, reduced site congestion, and limited spoil handling made micropiles an effective foundation solution for this historic, densely developed campus.

Keywords

micropiles

foundation upgrade

College of Charleston

Rita Liddy Hollings Science Center

deep foundations

Cooper River Marl

liquefaction risk

test piles

historic building renovation

low noise vibration