Ground-Penetrating Radar Survey for Subfloor Mapping and Analysis of Structural Damage in the Sagrado Corazon de Jesus Church, Spain

摘要

This work presents the results of a ground-penetrating radar (GPR) survey of the Sagrado Corazon de Jesus Church (seventeenth century AD). The church belongs to the artistic heritage of the Society of Jesus and is located in the old part of the city of Valencia (Spain). The GPR survey had two main objectives: discovering subfloor features and determining the causes of structural failure, particularly cracks and fractures detected in the building. For the fieldwork, 200 MHz and 400 MHz centre frequency antennae were used and a total of 53 profiles were acquired. The analysis of the reflection profiles and amplitude time-slices showed the presence of a sloping substrate below part of the church. The slope of this substrate and the fact that the church had been built near the old Arab wall of the city (eleventh century AD) suggests that the church was built on top of a moat (ditch). The variable thickness and differential compaction of the subfloor layers probably caused differential settlings in the building and therefore be the origin of some of the structural failures observed in the church. There was also a reflection hyperbola in the profiles of the east transept of the church that was hypothesized to be the reflection from the ceiling of an undocumented crypt due to its shape, size and location. That reflection feature was tested using a boroscope and found to be a brick barrel-vault crypt.