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

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The study evaluates methods for predicting the horizontal capacity of piles installed using Rotary Cutting Press-in (RCP), a displacement installation technique that may increase pile capacity through soil displacement. Conventional CPT-based p-y models were developed largely for other pile types and may not account for the soil compaction and stress changes caused by RCP installation.<br /><br />Researchers conducted one-dimensional finite-element analyses using a Winkler soil model and compared predictions from CPT-based p-y models, SPT-based methods, and the API model with field loading tests. The tested steel piles had an outer diameter of 318.5 mm. Horizontal capacity was defined as the load corresponding to 15 mm of pile displacement at the loading height. Measured capacities ranged from 65 to 103 kN.<br /><br />In general, CPT-based p-y models underestimated the horizontal capacity of RCP-installed piles, likely because they did not capture installation-induced changes in soil behavior. The API model showed better agreement with field measurements, but this may reflect overestimated soil friction angle and maximum shear modulus when those parameters are derived from CPT data, rather than superior modeling of RCP piles. Predictions from both CPT- and API-based approaches were sensitive to soil stiffness and strength parameters.<br /><br />The authors recommend adapting CPT-based models to account for installation effects and carefully calibrating and validating input parameters. They also advise using the API model cautiously when its parameters rely solely on CPT or SPT correlations.

Keywords

rotary cutting press-in

horizontal pile capacity

CPT-based p-y model

SPT-based method

API model

soil displacement

pile installation effects

Winkler soil model

finite-element analysis

field loading tests