Editorial Note - Vol. 16, No. 1, 2022-Article

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The 2022 DFI Journal issue focuses on deep foundations, including auger cast-in-place piles, drilled shafts, micropiles, and press-in piles.<br /><br />Jon Sinnreich and William Ryan evaluate concrete stressmeters as an alternative to strain gauges for compression testing of auger cast-in-place piles. Because the stressmeters directly measure stress in the cementitious material, they avoid relying on assumptions about modulus when converting strain to stress. The authors report on their use in two bidirectional static load tests.<br /><br />Timothy Stark and colleagues assess models for predicting drilled-shaft side resistance in weak, fine-grained Illinois rocks. Existing models, largely developed for stronger intact rock, performed poorly. The study found side resistance was independent of shaft diameter within the tested range and proposed a linear model for estimating resistance in these weak rocks. In a companion paper, the researchers introduce a Modified Standard Penetration Test (MSPT), which uses penetration rate to estimate rock strength and help determine drilled-shaft capacity.<br /><br />Maged Abdlrahem and M. Hesham El Naggar investigate steel-fiber-reinforced grout for hollow-bar micropiles. Laboratory bending tests showed improved capacity and post-cracking behavior; a large-scale lateral test found a 10% capacity increase with grout containing 1% micro-steel fibers.<br /><br />Bengt Fellenius and Siew Ann Tan examine how jacking press-in piles affects nearby granular soil. Pre- and post-installation cone tests showed substantial increases in cone tip resistance in loose sand, even several pile diameters from the piles.

Keywords

deep foundations

augur cast-in-place piles

drilled shafts

micropiles

press-in piles

concrete stressmeters

side resistance

modified standard penetration test

steel-fiber-reinforced grout

cone tip resistance