Abstract
In the agricultural expansion programme using the Aswan High Dam water, the additional discharge water in the Fayoum area is planned to be conveyed to the Wadi El Rayan depression via an underground tunnel. In the tunnel area, the rock types are mainly limestone and argillaceous sediments with some gypsum veins. Crushing strength of the encountered rocks is greatly influenced by the type of the specimens and their heterogeneity. X-ray examination of the −5μ fractions indicates the presence of a swelling mineral (abnormal montmorillonite) in some specimens together with β-disordered kaolinite, calcite, gypsum and quartz. Swelling pressure is mainly induced by the abnormal montmorillonite, being dependent on its amount. For the design of the tunnel a horse-shoe cross section is selected. The total length of the tunnel is recommended to be lined with reinforced concrete.
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