The Role of Geotechnical Properties of Rocks in Failure of Stability of the Funeral Subsurface Structures in Saqqara Plateau, Egypt : Part 1

This paper aims to interpret the instability of the subsurface structures which were hewn in Saqqara member through focusing mainly on the study of mineralogy and engineering properties of the three main units of Saqqara member. The representative samples were collected from different locations and depths, Ras-elgesr hill, Bobasteion hill, lower part of step pyramid. Samples were scanned by light microscope, analyzed using XRD, AIR, and TDS in addition to identifying the physical and mechanical properties. XRD showed that all the samples contain clay minerals the most were in the greenish grey samples while the least in white grayish samples. AIR, TDS and engineering properties of the three main units of Saqqara member showed that the white grayish layer has the highest density and compressive strength while they recorded the lowest value for porosity, water content, water absorption, AIR and TDS. The soft layer (marl and shale) has the lowest density, compressive strength while recording the highest value for porosity, water content, absorption, AIR and TDS. The results showed why the ancient Egyptian chose the white or yellowish layers to be the roof while the grayish and greenish grey or white marl (soft layers) to be the space of funeral subsurface structure of Saqqara member. The grayish, greenish grey layers and white marl have poor bearing capacities as a result of their mineralogical composition, physical and mechanical properties so they are unsuitable for most engineering construction and they are the main cause of failure in stability of most of the funeral subsurface structures in Saqqara.