The development of shaft friction and end bearing resistance for dynamically driven model piles

  • G. C. Lake

    Student thesis: Doctoral Thesis


    A pilot study was initially undertaken using a 38 mm pile to check the proposed static and dynamic instrumentation. A sophisticated control programme was then developed for the main tests using an Orion Data Logger interfaced with a Commodore PET micro computer. The static load data was stored on discs whilst the transient data was recorded on magnetic tape for later analysis.

    A pneumatically controlled rig was designed for driving the piles. The piles were driven from the surface adding sections at selected intervals. Inclinometers were installed in the soil to monitor vertical movements. The density of the soil was also measured at selected points at the end of the tests.

    The pile was driven to an embedded depth of 2 metres and then test loaded using the conventional CRP, MTL and Pull Out tests. The load distribution along the pile, together with the vertical movement of the soil was monitored at all stages. Changes in the shear and vertical stresses at the sand clay interface were also monitored and the final deformation of the clay beneath the pile tip.
    The data showed:-
    1. The pile top impact force was dependant on ram impact velocity only.
    2. The transient forces at the pile tip could be less than equal to or greater than the impact force depending on the nature of the bearing surface.
    3. The stress transfer curves exhibited a large value at shallow depth diminishing in value towards the toe.
    4. Vertical sand displacement decreased with increasing depth and radius.
    5. Insitu density increased towards the pile shaft by an appreciable amount.
    6. Soil movements were recorded across the sand clay interface during driving and test loading.
    7. Dragdown of sand into the clay along with a wedge of sand which preceded the pile tip was also observed.

    A theoretical approach for predicting static bearing capacity using the dynamic equations of motion and dynamic measurements is also outlined and compared with the authors experimental results. The agreement between experimental and theoretical thus achieved are encouraging.
    Date of AwardApr 1986
    Original languageEnglish
    Awarding Institution
    • Polytechnic of Wales

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