Identification and Classification of Soil and Rock

Every geotechnical decision starts with describing what is in the ground. This chapter covers how soils and rocks are identified and classified, from the overview of soil types and the Unified Soil Classification System to the Modified Unified System used for sample descriptions. It also covers how samples are logged and how rocks are described.

A section on special materials and difficult soils covers the ground that does not behave like a textbook case. Good descriptions make later calculations more reliable, and this chapter gives you a consistent way to record what you see so a boring log, a laboratory report, and a design all tell the same story.

In this chapter

• Introductionpage 32
• Soilspage 32
  • Overview of Soil Types
  • Unified Soil Classification System (USCS)
  • Modified Unified System (MUD)
  • Relative Density or Consistency
• Loggingpage 49
  • Comments on Drilling Procedures and/or Problems
  • Test Results
• Rockspage 52
  • Visual Classification
  • Classification by Field Measurements and Strength Tests
• Special Materials and Difficult Soilspage 61
  • Expansive Soils
  • Collapsing Soils
  • Permafrost and Frost Penetration
  • Limestone and Related Materials
  • Quick Clays
  • Sanitary Landfills
  • Other Materials and Considerations