GEOTECHNICAL STUDY FOR EVALUATING STABILITY AND RESTORATION WORK AT THE 1,000 YEAR-OLD ARCHAEOLOGICAL SITE OF AYLA, GULF OF AQABA, KINGDOM OF JORDAN

Geotechnical Investigations at the site of ancient Ayla in Aqaba, Jord an, show that soils are predominantly granular, with archaeological fi ll overlying beach sand, which in turn overlies a coarser sand and gra vel. Except for the wadi area, ground water occurs about 3 m below the existing ground level. The bearing capacity of the foundation is 3.5 kg/cm(2) for the dense granular materials that represent the probable founding layer of the existing walls, and 2.0 kg/cm(2) for the weaker silty/clayey zone. Back analysis yields a safe wall height of at least 6.0 m. Therefore, no stability problems are present. Tilting and sink ing were noted in some portions of the exterior malls as a result of d ynamic lateral earth pressures caused by a major earthquake incident i n 1067 A.D. Thus, wall-foundation support is recommended during archae ological excavations; and permanent excavations for exposing the walls should be limited to about 3 m by the western wall, and about 2.5 m b y the eastern wall. Stones used in the construction of ancient Ayla co nsist of precut sandstone, siltstone, mudstone and granite. Weathering effects were clearly noted on the exposed stones on the walls. The re placement stone should consist of sandstone blocks located 35 km north of Aqaba. Wall restoration includes replacement of mortar in the inne r walls and disintegrated stone pieces in the external walls. Existing mortars consist primarily of a brown silty mixture and a gray mixture , but also a mixture of fine gravel, and a lime/gypsum binder. The maj or chemical constituents of the original mortar are 18 percent SiO2, 2 3 percent CaO, and 34 percent SO3. X-ray diffraction peaks indicate th e presence of gypsum, calcite and quartz. Comparative analysis data ga ve 7 percent CaCO3, 53 percent sand, and 40 percent solubles as averag e values for the constituents. Two sand sources were identified for th e mortar mix; recommended mortar for restoration was a mix of lime, sa nd, and ash, with ratios of 1:3:1.5.