Case study: H-piles driven into shale rock for compression and uplift resistance

Abstract

The case study describes dynamic PDA tests conducted on four driven piles in fractured shale where rock penetration ranged from 0.98 to 2.3 m. The pile (HP360x174) was driven with a diesel hammer at a maximum rated energy of 100.47 kN-m. A steel shoe flush with the pile outside dimension was used. The piles reached practical refusal at 50 blows per 25 mm. The CAPWAP and estimated rock penetration established a unit tip bearing resistance of 24.9 MPa and a unit side resistance of 707 kPa. A plugged section was assumed. The unit side resistance is consistent with the recommendation in the AGMU10.2 manual by the Illinois DOT, but the tip resistance observed is almost four times what is recommended in the manual.