“Soil Mechanics” or DM 7.1 (UFC 3-220-10N) has been a valuable legacy document in geotechnical engineering for 50 years. Revisions to the document occurred in 1982, 1986, and 2005; but for the most part; the document has remained substantially unchanged since the original publication in 1971. DM 7.1 has been on the bookshelf of many civil engineers, it has been used in many graduate and undergraduate soil mechanics classed attended by generations of geotechnical engineering students, and charts and correlations from the document have been cited in numerous textbooks and research papers. Currently, it can be found in electronic format at a variety of sites on the internet.
The lasting value of DM 7.1 is attributed to its success in distilling geotechnical engineering design procedures, particularly into graphical examples that are easy to follow and understand. The manual also contains correlations to estimate engineering properties of soil and rock that have become ubiquitous in engineering practice. Although the manual continues to be a part of everyday engineering, changes in the profession necessitate a substantial update of DM 7.1. The manual was initially written when the slide rule was the main calculation tool of engineers. Subsequent revisions predate the widespread use of personal computer software tools that are used by every practicing engineer. The manual also predates the global use of the internet as a means to gather pertinent information and to transfer data and documents. In addition, there have been many new methods of testing, exploration, and analysis that have been developed since the publication of the original manual.
This current revision was undertaken with an emphasis on retaining the elements that were responsible for the lasting value of DM 7.1. Graphical examples of engineering solutions, both old and new, are found throughout the chapters. A new chapter has been written that focuses on geotechnical engineering correlations. Details about computer solutions and numerical modeling tools have been added to the manual. Owing to the rapid changes that occur in geotechnical engineering software tools and internet addresses, the authors have tried to minimize the number of URLs and the names of specific software packages in the text. Appendix B contains a listing of software packages available at the time of publication (2021), along with vendor contact information, with the intention that this appendix can be updated periodically in the future.