The Jiayuguan Fortress: structural consistency and safeguarding programs

The Jiayuguan Fortress (Ming period, 14th century), stands at the end of the Great Wall of China, facing the Gobi desert. The building consists of a large square-shaped enclosure wall, enhanced by two entrance courtyards, to which a further external wall was added in the 15th century. The building is made by rammed earth at the bottom and by adobe bricks at the top; but a brick "coat" was added on some parts of the original artefact causing an obstruction in the "breathing" movements of the massive inner core. This masterpiece represents an important testimony of the old defense techniques based on earthen walls or embankments. After a survey on the principal techniques used for the construction of defensive earthen walls, the paper investigate the main structural weakness, analyzing the connection among employed building techniques, cracks pattern, intervention phases and exposure to meteoric actions, suggesting guidelines for a safeguarding strategy.