Engineering failure analysis and design of support system for ancient Egyptian monuments in Valley of the Kings, Luxor, Egypt

Background: The paper represents the first comprehensive experimental and numerical study for engineering failure analysis and appropriate design for the permanent mechanical support system for the tomb of the Sons of Ramesses II (KV5). It is, in fact, one of the largest rock cut tombs ever found in Egypt. During the late 18th Dynasty and throughout the19th, the tombs are usually located further down the Valley some distance from the rock walls. The builders often quarried through talus slopes, such as in the case of the tomb of Sons of Ramses II. It is clear that the tomb of sons of Ramsses II is much more susceptible to surcharge geostatic loading from the overburden rock strata, rock bursting, and structural damage of support pillars and walls induced to the water and past/recent flash floods impacts caused by heavy rain in the Valley. Since some of this tomb also makes contact with the underlying shale layers, that have the potential for swelling and shrinkage under changing moisture conditions. Expansive damages to these underground structures have been widely noticed in the Valley of the Kings. This tomb tends to be the worst preserved tomb in the Valley of the Kings. The Esna shale in the valley is particularly weak and unstable. It not only posed problems to the ancient quarryman, but to the modern conservator as well. When the shale comes into contact with moisture, it expands and can literally tear a hill side apart. Results: The main adjectives of the geoenvironmental and geotechnical analyses carried out in the present study are to investigate the static stability, safety margins and engineering failure of the tomb of Sons of Ramsses II (KV5) under their present conditions, against unfavorable environmental (i.e. extensive weathering due to water and flash floods impact in the past and present), utter lack of preservation, geostatic overloading of structural rock support pillars, geotechnical and extreme seismic conditions. Also to design an appropriate geotechnical support system, according to the engineering rock mass classification, in particularly the rock mass rating RMR and quality rock tunneling index Q-system. Conclusions: The engineering analysis had been carried out through the following four steps: 1-Evaluation of the surrounding rocks (marl limestone) by experimental investigation and the Roclab program to obtain Hoek Brown Classification criterion, Mohr- Coulomb fit and the rock mass parameters in particular the global strength and deformation modulus. 2- Qualitative and quantitative estimations of relevant factors affecting the stability of the tomb in particularly the overburden or geostatic and dynamic loading. 3- 2D and 3D integrated geotechnical modeling of the tomb environment for stress, displacement analyses and determination of volumetric strains and plastic points using advanced codes and programs like Examine 2D and PLAXIS 3D. The numerical analysis results indicated that the safety factor of the rock pillar structural supports is 1.37 and the overstress state is 1.28 MPa. 4-Remedial and retrofitting policies and techniques, static monitoring and control systems which are necessary for the strengthening and stability enhancement of the tomb, where the rock mass classification indicated the rock mass where the KV5 is excavated is poor rock, with RMR 39 and Q value 1.87. Based on the underground engineering stable equilibrium theory and rock mass classification, three support structure techniques are provided and detailed illustrated with the case of KV5 in this study. © 2018, The Author(s).