Notice for e-book users Principles of Rock Mechanics is distributed free of cost, as an e-book, and anyone may freely use or further disseminate this textbook. No person or institution shall charge any cost for the use or distribution of this e-book. This book is intended for self-study, use in university courses and/or professional training. The inclusion of exercises in each chapter helps the user to quickly grasp the meaning of elementary concepts. Answers to the exercises are given in the back of the book. Principles of Rock Mechanics has been distributed worldwide in hard copy - to over 60 countries – during the first few years after its publication in 1997 and was reprinted in 1998. Active marketing and distribution ceased in 2001, but bookshops from around the world kept ordering the book for their clients. Users praised the book for its practical approach. Unfortunately, the book was no longer available in hard copy since 2005. This book, was written in the 1990s, and sponsored by Uppsala University (Sweden) and King Fahd University of Petroleum and Minerals (Saudi Arabia). The intellectual property rights for this book are held by Alboran Science Publishing. Their support for the global distribution of this e-book is kindly acknowledged. My hope is that this e-book can still serve as a valuable teaching and training aid. This is exactly what the book was written and published for in the first place. Delft, January 2011 Ruud Weijermars Department of Geotechnology Delft University of Technology The Netherlands