Interpretation of Driven Tubular Pile with Soil Plug Test Results Using the Wave Impact Theory-Paper

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The study develops and evaluates a wave-impact method for interpreting dynamic tests of driven tubular piles while accounting for soil plugs—an effect not adequately represented by commonly used programs such as PDI and CAPWAP.<br /><br />Three 1,420 mm-diameter steel piles at a bridge site near Murmansk were redriven after at least seven days of relaxation using a 30-tonne MENCK hammer. Strain gauges and accelerometers recorded pile response. The researchers estimated soil-plug formation using a model based on Janssen’s pressure distribution in cylindrical containers, then represented the pile and plug as rods with different effective masses. A finite-difference solution of the wave equation incorporated soil resistance, damping, and elastic and viscous effects. Calculated forces, velocities, strains, and residual displacements were compared with measurements and code-based resistance estimates.<br /><br />Measured and calculated dynamic responses showed broadly similar patterns, supporting the method’s practical usefulness. The model also reproduced jumps in forces and velocities near the top of the soil plug, indicating that plug formation affects force distribution along the pile. Comparisons suggested that a plug can increase lateral resistance while reducing the proportion of resistance at the pile tip. A simulation without a plug showed lower overall resistance and no corresponding response jump.<br /><br />The authors conclude that their method gives acceptable results for simulating the driving and dynamic testing of tubular piles with soil plugs. They recommend considering closed-ended piles where soil conditions are unlikely to produce a stable plug, and comparing dynamic-test results with static pile tests.

Keywords

wave-impact method

dynamic pile testing

tubular piles

soil plug

wave equation

finite-difference solution

Janssen model

pile driving

soil resistance

CAPWAP