This book focuses on learning and adapting nonlinear geometry tool in rock engineering through fractal theories, hypotheses, algorithm, practical understandings, and case studies. Understanding self-similarity and self-affinity is a prerequisite to the fractal model in rock mechanics. The book aims to provide a guide for the readers seeking to understand and build nonlinear model by fractal algorithm. The book is motivated by recent rapid advances in rock engineering in China including application of fractal theory, in addition to percolation theory. It is an essential reference to the most promising innovative rock engineering. Chapters are carefully developed to cover (1) new fractal algorithms (2) five engineering cases. This authored book addresses the issue with a holistic and systematic approach that utilizes fractal theory to nonlinear behavior in rock engineering. The book is written for researchers interested in rock and geological engineering as well as organizations engaged in underground energy practices.