The first International Conference on Analysis of Discontinuous Conference (ICADD) was held in Taiwan in 1995. Since then, it has been hosted in sequence in Japan (1997), USA (1999), UK (2001), Israel (2002), Norway (2003), USA (2005), China (2007) and Singapore (2009). The conference series aims to exchange ideas and new developments in the various modeling methods for discontinuous deformation. It also promotes the application of the developed methods to rock engineering problems, including but not limited to stability analysis of rock slope, storage carvern, rock tunnels, and underground power stations; and more recently in stress wave propagation in rock mass; rock support design; failure of heterogeneous rock materials; and mining.

This book contains the technical papers presented at the 9th International Conference on Analysis of Discontinuous Deformation (ICADD9) held at the Nanyang Technological University (NTU), Singapore on 25-27 November 2009. These papers represent the most recent advances and developments in the increasingly important field of discontinuous deformation analysis in rock mechanics and engineering. Following the tradition of the conference series, the main schemes of ICADD9 are on the key block theory and its engineering applications, the discontinuous deformation analysis (DDA) method and the numerical manifold method (NMM). However, other relevant topics, for example, the distinct/discrete element method, the meshless method, the finite element method in rock mechanics and engineering applications are also included.

ICADD9 received more than 140 abstracts from 17 countries. After a vigorous selection and review process, just over 80 papers were accepted for oral presentation at the conference and for inclusion in this book. Still, these represent the largest number of papers presented at the ICADD Conference series.

We would like to acknowledge the authors and speakers for their contribution to ICADD9. Special thanks are due to Dr Genhua Shi for his continuous support and encouragement. Thanks are also due to CMA International Consultant Pte Ltd for their secretariat support. The Underground Technology & Rock Engineering team of NTU and the Defence Science and Technology Agency also provided technical support for the conference.

The successful organization of ICADD9 would not have been possible without the untiring efforts of the organizing committee. Their volunteering but efficient works helped the planning and organizing stages in a great success. We would also like to extend our gratitude to the following sponsors for their support: Tritech Group Pte Ltd, Singapore; Basissoft, LLP, Korea; The Yangtze River Scientific Research Institute, China; Advance Contech (S) Pte Ltd, Singapore; SK E&C Singapore Branch; Hyundai Engineering & Construction Co. Ltd, Korea; Knights Synergy (S) Pte Ltd, Singapore; Dongah Geological Engineering Co Ltd, Singapore.

Guowei MA and Yingxin ZHOU