Restoration Project of vernacular architecture affected for ground subsidence. A case study in Juslibol Church (Zaragoza, Spain)

Abstract

[EN] At the request of the Archbishopric of Zaragoza, an exhaustive study of the situation of the parish church dedicated to the Assumption of Our Lady (18th century) in Juslibol (Zaragoza) has been carried out since 2011. It was built between 1758 and 1784. The church was built on a hillside with a medium-low slope, excavating in a loose colluvial soil formed by silt-clay materials with fragments of marl-gypsum rock. and pebbles of gravel and sand from the terrace deposits located in the highest part of the slope. Once the plot was leveled, the ground would be prepared and the foundation elements would be excavated (apparently continuous trenches) according to the design of the projected building floor plan. This church has suffered for many years from deformation and settling problems caused by the combination of several especially unfavorable factors, such as: the poor quality of the support ground, its sloped location halfway up the hillside, and leaks-filtrations from a supply network, and especially sanitation, which have favored processes of dissolution-undermining of the land below the foundations. The part facing south, including the tower, registered differential settlements with respect to the part further into the hillside. Once this situation was assessed, it was underpinned by means of jet-grouting columns and, apparently, the measure was effective. However, the cracks now observed are not explained within a differential settlement process.