Development of the Rapid Plate Load Test (RPLT) and its application to the assessment of stone columns -

Abstract

The introduction of new and more reliable tools for testing shallow and deep foundations has always been intrinsic to the advancement of geotechnical engineering practice. This thesis aims to introduce a novel testing methodology for conducting quasi-static load tests aimed at quantifying the load-displacement response of shallow foundations at a given site. This testing methodology will be referred to as the Rapid Plate Load Test (RPLT). The apparatus developed and tested in this thesis was inspired by the falling weight deflectometer used in pavement assessment and the drop hammer commonly used in the dynamic testing of piles. The object of the test is to evaluate the response of 2 x 2 meter footing to pressures of up to 500 kPa. The design process of the RPLT consisted of a number of trial and iterations aimed at meeting structural constraints-considerations, the adaptation and incorporation of a precise and reliable instrumentation array, and the development of acquisition and data processing software. The field testing component of the research involved the execution of gravel-stone columns in a clayey substratum at a research station in the Beqaa region of Lebanon, specifically identified and prepared for the purpose of this work. The test site was thoroughly investigated and characterized through a comprehensive field and laboratory testing program. Validation tests involving rapid load as well as standard static experiments were conducted on arrays of stone columns supporting a loading pad. The stone columns were executed using the dry method and were 6m deep, penetrating a slightly overconsolidated clay. The apparatus setup was tested and modified to improve repeatability and the mechanical behavior of the impact cushion, which is key in defining the force-pulse nature and duration. The results obtained for the static load tests were analyzed-evaluated to confirm site characterization. Finite element modeling was used to predict static load settlement at footings improved at area replacement ratios othe