Development of Load and Resistance Factor Design Procedures for Driven Piles on Soft Rocks in Wyoming

2019Final Report \u2013 March 22th, 2016 to June 30th 2019PDFTech ReportWY-1902FRS06216CalibrationLoad and resistance factor designLoad factorPile drivingPiles (Supports)Soft soilsState of the practiceDriven pilesIntermediate geomaterialsLoad and Resistance Factor Design (LRFD)Geomaterial classificationStatic AnalysisWave EquationWyomingUnited StatesWyoming. Dept. of TransportationNg, KamAdhikari, PramilaGebreslasie, Yrgalem ZUniversity of Wyoming. Dept. of Civil and Architectural EngineeringWyoming. Dept. of Transportation. Research CenterUS Transportation CollectionStatic Analysis methods originally developed for soils are currently used for estimating pile resistances in Intermediate Geomaterials (IGMs), and structural capacity has been considered as the limiting pile capacity on hard rocks. The application of current Load and Resistance Factor Design (LRFD) for piles in IGMs has resulted in relatively high uncertainties in pile resistance estimation during design and the length to which the piles are driven into IGMs during construction. Moreover, the absence of standard criteria to differentiate the geomaterials creates challenges in the design and construction of driven piles in IGMs. The application of a dynamic analysis method using Wave Equation Analysis Program is constrained by geomaterial input for IGMs and rocks. These current challenges have led to conservative pile resistance estimations. Thus, the overall objectives of this study were to determine efficient static analysis methods, dynamic procedures for construction control, pile setup/relaxation, and resistance factors for the estimation of the axial pile resistances in IGMs, ensuring a prescribed level of reliability to meet LRFD philosophy. To accomplish these objectives, classification criteria of geomaterials were first created to establish a standard quantitative delineation between the soils, IGMs, and hard rocks for the design of driven piles. In addition, a catalog of IGM properties was prepared to facilitate the design of piles in IGMs. Secondly, a new set of design equations were developed and validated for IGMs by utilizing the developed geomaterial classification criteria. Thirdly, wave equation analysis procedures for IGMs were recommended for pile construction control. Fourthly, changes in pile resistances in IGMs with respect to time at the end of driving and beginning of restrike were assessed. Finally, probability based resistance factors were calibrated and recommended based on the efficiency factors for the existing and calibrated static analysis methods. To facilitate the implementation of the recommended LRFD procedures, a pile design example is developed.83