Geotechnical investigation and stabilization of the foundations of a World Heritage in Portugal, the Guimarães Castle

摘要

Conservation and restoration of monuments and historical areas are disciplines that require specific training. The forts and castles are among these monuments that present high complexity due to the elevate nature of the forts. Each fort and castle has distinctive engineering and architectural features that turn its study a challenge. In this paper, the methodologies followed in the studies and investigations on ancient forts carried out at University of Porto are briefly presented. Studies concerning forts with Portuguese legacy are presented. In particular, a specific study is presented focusing on the rehabilitation of foundations and walls of Guimarães castle in Portugal. Preliminary diagnosis of the castle walls has shown important pathologies in two walls, one of them located in the north tower where apparent cracks and joint openings were clearly visible. In the latter, the cracking pattern was consistent with possible foundation movements that were found likely to be responsible for wall corner rotation which induced signs of stones’ crushing in the wall base in contact with the foundation rock mass. An assessment of the causes of the appearance signs of holes or torn threads in the exposed face of the wall and tower of the extreme southwest of the castle was done, after the site survey with geotechnical laboratory tests. The intervention performed was focused both on the foundation and the walls, starting by the foundation stabilization by nailing a set of high-strength blocks of rock mass and careful sealing of the massive network of high strength and consolidation of the most altered and fractured. Subsequently, the wall cracks and joint openings should be repaired, but structural monitoring was started beforehand in order to control any possible movements both during the geotechnical works and for a three year long period after repairing cracks and joints. Construction issues including logistics and problems found are described, as well as the main outcome of the monitoring process and the finally adopted structural interventions.