3 GEOTECHNICAL SITE CHARACTERIZATION FOR DESIGN OF LATERALLY LOADED DEEP FOUNDATIONS 3.1 INTRODUCTION This chapter presents information on the characterization of subsurface conditions for design and constructability assessments of laterally loaded deep foundations. The intent of this chapter is not to repeat detailed information presented in other publications, but rather to focus specifically on considerations for applications where lateral loads on deep foundations maybe a significant aspect of the foundation design, as well as the development of parameters that maybe specifically needed for laterally loaded deep foundation analyses. Subsurface investigations and evaluation of soil and rock parameters in general are addressed in Subsurface Investigations (Mayne et al. 2002) and Geotechnical Site Characterization (Loehr et al. 2016). Specific requirements for LRFD design considerations are addressed in Article 10.4 of the AASHTO LRFD Bridge Design Specifications (2014). Subsurface characterization for design and construction of deep foundations for transportation projects is addressed in other publications for drilled shafts (Brown et al., 2010), CFA piles (Brown et al. 2007), and driven piles (Hannigan et al. 2016). Those publications include details regarding planning of subsurface investigations, testing programs, and development of geotechnical parameters for analysis of those types of deep foundations. Regardless of the type of deep foundation, the subsurface investigation and testing program must be adequate for the design of the deep foundation system, including design for lateral loading. The selection of resistance factors for design in the LRFD framework, discussed in Chapter 4, is based in part on the adequacy of the investigation and testing program. For the analysis and design of piles/shafts under lateral loads, all geomaterials are categorized as either granular soils, cohesive soils, rock, or cohesive intermediate geomaterial (IGM).
