Geotechnics in the preservation of Machu Picchu, Cusco, Peru

Abarca Ancori A. · Built Heritage (2025) · DOI: 10.1186/s43238-025-00192-1

Resumen

The Incan foundation techniques that have allowed the buildings of Machu Picchu to endure to the present are unknown. In this sense, one possible intervening factor is the proper application of geotechnical principles. This application guarantees the preservation of civil works through the effective management of local conditions and the physical and mechanical characteristics of soils. Therefore, the objective of this research was to determine whether geotechnics were related to the preservation of the Llaqta of Machu Picchu. For this purpose, three geotechnical factors were evaluated: 1) local site conditions, 2) physical and mechanical characteristics of the foundation soils, and 3) bearing capacity. These factors were observed in the natural context of the Machu Picchu buildings via in situ and laboratory tests with standardized, noninvasive, and nondestructive equipment and procedures. The results revealed that the foundation soils are composed of two strata: 1) Inca Controlled Fill (ICF), made up of gravel, and 2) a granodioritic igneous rock massif, which has a strength of 320 kg/cm2 in situ and 771 kg/cm2 in the laboratory. The strata exhibit friction angles of 31° and 38° and densities of 1.94 and 2.34 Tn/m3, respectively. These geotechnical parameters yield a bearing capacity of 9.6 kg/cm2 under a vertical stress of 1,156 kg/cm2. Therefore, it is concluded that the Incas, possibly on the basis of ancestral wisdom and trial and error, empirically employed geotechnical principles, providing suitable conditions for the preservation of the buildings at Machu Picchu. © The Author(s) 2025.

Instituciones: Universidad Nacional de San Antonio Abad del Cusco; Universidad Nacional del Altiplano