CPT and Data Reduction
Our client was tasked with designing replacements/ reconstructions of the existing toll plaza, exit ramps, and bridges of I-895. We conducted SPT borings for this project but suggested supplementing the bridge abutment borings with CPTs to support a more cost effective design.
Statement While we had traditionally only performed CPT testing on non-pavement surfaces, where we could anchor into the soil to generate an appropriate reaction force, we were able to custom build a concrete anchoring system for our rig in our machine shop. We performed the CPTs at night and conducted pore pressure dissipation testing throughout.
CPT testing and subsequent data reduction yielded modulus and shear strength values that were ~1.5-2x higher than those calculated from SPT N Values in nearby borings. Moreover, end bearing capacity and skin friction values for different pile designs were roughly 1.5-2x higher as well.