Testing Layout > Reaction Foundation
To increase the lateral capacity of the shafts being used as a reaction foundation, a sheet pile wall was installed on the north side of the drilled shafts. AZ-18 sheet piling constructed of ASTM A-572, Grade 50 steel was used, being selected from sections readily available in the local area. Installation depth was controlled by the 40 ft length of the available stock. The piling, as built, extended to depths of 33.5 to 35.5 ft below the excavated ground surface. The sheet pile was installed by vibratory hammer, and the sheet piling was kept as vertical and flush with the faces of the shafts as possible.
To help ensure a composite behavior and proper load distribution, two 28-ft long, 64- by 16-in I-beams with numerous stiffeners were placed with the web horizontal on either side of the shafts and sheet piling. The reaction foundation was tied together with eight 2.5-in diameter high strength threaded bars that were post-tensioned to 10 kip.