Monitoring and Modelling the Thermally Assisted Deformation of a Rock Column Above Tomb KV42 in the Valley of the Kings, Egypt

Abstract

The Valley of the Kings (KV) is located within a large funerary landscape called the Theban Necropolis, in Luxor, Egypt. In 2018, our team started to monitor the transient conditions of a 15 m rock column of micritic limestone above the tomb KV42 and a fracture located at the west end of the column (lateral fracture), registering thermo-mechanical displacements with a crack metre, infrared thermographic sensor, and a weather station. The data from April 2018 to May 2021 showed seasonal fluctuations in the rock surface temperature (RST) from 12°C (winter) to 45°C (summer), as well as an average reversible fracture opening (FO) rate of 1 mm/year. The measured average thermo-mechanical ratio of FO to RST was 0.05 mm/°C. Data collected at the site were used to calibrate a finite difference model in FLAC®8.0 for thermo-mechanical simulations. The results showed a correlation (R2) of 0.8 between measured data and elastic isotropic mechanical constitutive model results, with a ratio of FO to RST equal to 0.03 mm/°C and rates of reversible displacements of 0.8 mm/year, whereas the average irreversible displacement for the monitored period of 2018–2021 was 0.2 mm/year. The insights from this study can help provide a preservation approach for this area of the UNESCO World Heritage site and also enhance our understanding of environmentally driven long-term fracture growth mechanisms, such as thermo-mechanical fatigue. In the future, such insights could become more important as the global and local magnitude of daily and annual temperature fluctuations continue to increase.