Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
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Soldier Rev B
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- 3.2.1 Soil Geotechnical Design Parameters
- Table 3-1: Geotechnical parameters for analysis of laterally loaded deep foundations in soils. Material Parameter: Basic Parameter
- 3.2.2 Rock Geotechnical Design Parameters
| 3.2 GEOTECHNICAL DESIGN PARAMETERS Subsurface investigations should consider geotechnical design parameters needed for analysis of deep foundations under lateral loads. Parameters needed for both soil and rock typically used in p-y analyses, described in Chapter 6, are identified in this section. Procedures for obtaining geotechnical parameters are outlined in GEC 5, Geotechnical Site Characterization (Loehr et al. 2016). 3.2.1 Soil Geotechnical Design Parameters The analysis of deep foundations under lateral loads requires various geotechnical parameters including basic strength, stiffness, and deformation parameters. These are summarized in Table 3-1 for both cohesive and cohesionless soils. 32 Table 3-1: Geotechnical parameters for analysis of laterally loaded deep foundations in soils. Material Parameter: Basic Parameter: Strength Parameter: Deformation Parameter: Stiffness Cohesive Soils) Unit Weight, γ Poisson’s ratio, ν Undrained Shear, S u Strain, ε 50 Subgrade Modulus, k Cohesionless Soils Unit Weight, γ Poisson’s ratio, ν Friction Angle, φ NA Subgrade Modulus, k Elastic Modulus, E Notes (1) Including cohesive IGMs treated as clay-type materials for analyses. Refer to Table 3-2 for parameters if IGM is treated as weak rock. Additional parameters maybe needed for vertical loading considerations, constructability and other aspects of deep foundation design not addressed in this manual. 3.2.2 Rock Geotechnical Design Parameters It is important to distinguish properties of intact rock and properties of the rock mass when assessing geotechnical parameters for design of laterally loaded deep foundations. Intact rock refers to the consolidated and cemented particles that form the rock material and is characterized by index and strength properties of rock samples recovered from rock coring operations. Rock mass refers to the mass of intact rock and discontinuities including joints and fractures that breakup the intact rock. Rock mass is characterized by the properties of the intact rock materials and the characteristics of the discontinuities Brown et al. 2010). The information presented in this section applies to materials defined either as rock or as cohesive intermediate geomaterials (cohesive IGM). Cohesive IGM is defined as material that exhibits unconfined compressive strengths in the range of 10 ksf to 100 ksf. In some cases, these materials may also be referred to as soft rock or very weak rock. Specific materials identified by O’Neil el at. (1996) as being cohesive IGMs include (1) argillaceous geomaterials such as heavily overconsolidated clays, clay shales, saprolites, and mudstones that are prone to smearing when drilled, and (2) calcareous rocks such as limestone and limerock and argillaceous geomaterials that are not prone to smearing when drilled. Rock maybe characterized as soft rock or hard rock. For driven piles, soft rock generally refers to rock that can be penetrated by pile driving operations. Hard rock in pile driving operations generally refers to rock that cannot be penetrated by pile driving. For drilled shaft operations, hard rock may refer to rock that requires special tooling for shaft excavation such as rock augers, core barrels, downhole hammers, or chisels. The analysis of deep foundations under lateral loads, specifically p-y analysis, requires various geotechnical parameters for rock, such as basic strength, stiffness, and deformation parameters. These are summarized in Table 3-2. Not all parameters presented in Table 3-2 are used in every type of lateral pile analysis. Download 6.03 Mb. Share with your friends:
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