CPT based design method for horizontal and vertical capacity of piles installed by the Rotary Cutting Press-in method-Paper

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The study evaluates whether existing cone penetration test (CPT)-based soil-resistance models can predict the horizontal capacity of piles installed using the Rotary Cutting Press-in (RCP) method, which combines static jacking and rotation. RCP installation can compact surrounding soil and redistribute stresses, potentially improving pile performance.<br /><br />Researchers conducted field tests on 10 small-diameter pipe piles in sandy soil, including open- and closed-ended piles and different installation load limits. Horizontal loading tests were compared with one-dimensional finite element analyses using Winkler springs and several CPT-based p-y models, as well as the API model. Measured horizontal capacities—defined at 15 mm displacement—ranged from 65 to 103 kN.<br /><br />Most existing models, including the CPT-based models, underestimated the measured response and horizontal capacity. The likely reason is that they do not account for soil changes caused by RCP installation, including compaction and stress redistribution. The API model generally predicted higher capacities, but this may reflect overestimated soil parameters—particularly internal friction angle and maximum shear modulus—rather than greater model accuracy.<br /><br />The findings indicate that CPT-based p-y models need to incorporate installation effects to provide more reliable predictions for RCP piles. API predictions also require caution when their soil inputs are derived from CPT or SPT correlations; key parameters should be validated where possible.

Keywords

cone penetration test

CPT-based soil resistance

horizontal capacity

pile foundation

rotary cutting press-in

RCP method

sandy soil

p-y models

installation effects

finite element analysis