The work of geotechnical engineers contributes to the creation of safe, economic and pleasant spaces to live, work and relax all over the world. Advances are constantly being made, and the expertise of the profession becomes ever more important with the increased pressure on space and resources. This book presents the proceedings of the 15th Pan-American Conference on Soil Mechanics and Geotechnical Engineering (XV PCSMGE), held in Buenos Aires, Argentina, in November 2015. This conference, held every four years, is an important opportunity for international experts, researchers, academics, professionals and geo-engineering companies to meet and exchange ideas and research findings in the areas of soil mechanics, rock mechanics, and their applications in civil, mining and environmental engineering. The articles are divided into nine sections: transportation geotechnics; in-situ testing; geo-engineering for energy and sustainability; numerical modeling in geotechnics; foundations and ground improvement; unsaturated soil behavior; embankments, dams and tailings; excavations and tunnels; and geo-risks, and cover a wide spectrum of issues from fundamentals to applications in geotechnics. This book will undoubtedly represent an essential reference for academics, researchers and practitioners in the field of soil mechanics and geotechnical engineering. In this proceedings, approximately 65% of the contributions are in English, and 35% of the contributions are in Spanish or Portuguese.

Machu Picchu, recently voted one of the New Wonders of the World, is one of the world's most famous archaeological sites, yet it remains a mystery. Even the most basic questions are still unanswered: What was its meaning and why was it built in such a difficult location? Renowned explorer Johan Reinhard attempts to answer such elusive questions from the perspectives of sacred landscape and archaeoastronomy. Using information gathered from historical, archaeological, and ethnographical sources, Reinhard demonstrates how the site is situated in the center of sacred mountains and associated with a sacred river, which is in turn symbolically linked with the sun's passage. Taken together, these features meant that Machu Picchu formed a cosmological, hydrological, and sacred geological center for a vast region.