Description:

INTRODUCTION This manual provides guidelines and instructions for performing and documenting field work. The manual is a ready reference for anyone engaged in field-oriented engineering geology or geotechnical engineering. The manual is written for general engineering geology use as well as to meet Reclamation needs. The application of geology to solving engineering problems is emphasized, rather than academic or other aspects of geology. The manual provides guidance for: Geologic classification and description of rock and rock discontinuities Engineering classification and description of soil and surficial deposits Application of standard indexes, descriptors, and terminology Geologic mapping, sampling, testing, and performing discontinuity surveys Exploratory drilling Soil and rock logging Acquisition of groundwater data Core logging Soil logging Investigation of hazardous waste sites Although the methods described in this manual are appropriate for most situations complex sites, conditions, or design needs may require modification or expansion of the suggestions, criteria, and indices to fit specific requirements. Many of the chapters in this manual will always need revision because they cover material that changes as technology changes. Critical comments, especially suggestions for improvement, are welcome from all users not just the Bureau of Reclamation. The appendix contains abbreviations and acronyms commonly used in engineering geology. GEOLOGIC TERMINOLOGY AND CLASSIFICATIONS FOR GEOLOGIC MATERIALS Established references for geological terminology adaptations or refinements of the Bureau of Reclamation (Reclamation) standards presented in this and subsequent chapters may be established to meet specific design requirements or site-specific geologic complexity when justified. The Glossary of Geology, Fourth Edition published by the American Geological Institute (AGI), 1997 is accepted by Reclamation as the standard for definitions of geological words and terms except for the nomenclature, definitions, or usage established in this chapter and chapters 3, 4, and 5. The North American Stratigraphic Code (NASC) is the accepted system for classifying and naming stratigraphic units. However, Reclamation's engineering geology programs are focused primarily on the engineering properties of geological units not on the details of formal stratigraphic classification. Stratigraphic names are not always consistent within the literature often change from one locality to another and do not necessarily convey engineering properties or rock types. Use of stratigraphic names in Reclamation documents normally will be informal (lower case) see NASC for discussion of formal versus informal usage Exceptions to informal usage are for names previously used formally in the area in discussions of geologic setting or regional geology The first use of formal names in a report should include a reference to a geological map or publication in which the term is defined. Geologic Classification of Materials The following definitions of geologic materials more fully satisfy general usage and supersede those in the Glossary of Geology. These definitions are for geologic classification of materials They should not be confused with engineering classifications of materials such as rock and soil or rock and common excavation Bedrock is a general term that includes any of the generally indurated or crystalline materials that make up the Earth's crust Individual stratigraphic units or units significant to engineering geology within bedrock may include poorly or non-indurated materials such as beds lenses or intercalations These may be weak rock units or interbeds consisting of clay silt and sand such as the generally soft and friable St Peter Sandstone or clay beds and bentonite partings in siliceous shales of the Morrison Formation Surficial deposits are the relatively younger materials occurring at or near the Earth's surface overlying bedrock They occur as two major classes transported deposits generally derived from bedrock materials by water wind ice gravity and man's intervention and residual deposits formed in place as a result of weathering processes Surficial deposits may be stratified or unstratified such as soil profiles basin fill alluvial or fluvial deposits landslides or talus The material may be partially indurated or cemented by silicates oxides carbonates or other chemicals caliche or hardpan This term is often used interchangeably with the imprecisely Ключевые слова: e, r, o