Jet Grout Foundations to Resist Compressive, Uplift and Lateral Loads at an Operational Power Plant

As a value engineered, design-build alternate to the original foundation design, an innovative jet grout foundation system was proposed to support various combinations of compressive, uplift and lateral loads of a new selective catalytic reduction (SCR) unit at an operational power plant. Site geology consists of fill over 9 m (30 ft) of clayey silt over dense sand and gravel. Due to the high magnitude of the SCR foundation loads, site geology, and construction access restraints presented by the existing structures and process piping, the original design specified minipiles. The original design also called for thick pile caps requiring extensive excavation support and underpinning of existing foundations. The proposed jet grout solution required reduced drilling, minimum excavation support and less underpinning thereby decreasing construction time and cost. An extensive field-testing program was developed to verify design calculations and assumptions for the jet grout alternate. Testing included a full-scale jet grout column compression test, tension test and in-situ coring. This paper presents a project overview along with a review of geotechnical conditions, the original design, the alternate jet grout foundation system, jet grout design assumptions and the confirmatory testing program.