Camp Road Middle School
Camp Road Middle School
Project Details:
Owner: Charleston County School District
General Contractor: Hill Construction
Date of Work: March 2018
Engineer: S&ME, Inc.
Approximate Key Quantities: Wick Drains - 4,500 LF
Project Overview:
Ground Conditions:
Solution:
Among the challenges faced were liquefiable soils, including saturated, clean to silty sands at least 40 feet in thickness. Liquefaction occurs when a saturated or partially saturated soil substantially loses strength and stiffness in response to an applied stress such as shaking during an earthquake or other sudden change in
stress condition, in which soil behaves like a liquid.
The project Geotechnical Engineer, S&ME, predicted up to 5 inches of free-field, liquefaction-induced settlements as a possibility without ground improvement. The Liquefaction Potential Index (LPI) was greater than 15, suggesting severe liquefaction and foundation damage if liquefaction would occur.
S&ME recommended either EQ drains or vibro-replacement stone columns from the outset for liquefaction mitigation. EQ drains – which mitigate liquefaction by providing a drainage path and reducing excess pore water pressure generated by earthquake loading -- would prove to be the most economical solution.
USW designed and installed 4,491 EQ drains covering 105,761 linear feet. USW designed the EQ drains to mitigate liquefaction and to limit liquefaction-induced settlements to less than 2 inches. USW also performed pre and post-install CPTs to study the densification of the site soils, which is a corollary benefit of this ground improvement technique and helps to reduce the risk of liquefaction by increasing the soil’s cyclic resistance ratio.
To support the construction of a new, two-story middle school in Charleston, SC, USW installed 4,491 EQ drains to mitigate liquefaction. All work was completed in one continuous phase and USW met the client’s requirements for safety, quality and schedule.
