Plate load test on rock with soaking under a massive raft foundation

The Iconic Tower, a 385.8 m high-rise building, is the landmark of Egypt New Capital’s Central Business District project and will be the tallest building in Africa when completed. The location of the Iconic Tower is underlain by basalt rock and supported by raft foundation. Obtaining the accurate performance parameter experimentally is key to foundation design. Due to high elastic modulus of the rock, settlement of the bedrock under design load is estimated around 2 mm, which is sensitive to any millimeter-scale errors that may cause deviation to the result. The high flatness and stiffness of loading plate and the underlying grout bedding is key to minimize the error. The results show that the behavior of bedrock under the range of test stresses can be closely presented by a bilinear elastic stress deformation. Excavation-induced disturbance leaves open joints and fractures in the bedrock which produce plastic settlement in the bedrock under loading in addition to the settlement caused by soaking the bedrock under the design load for 24 h. The present study was able to overcome various challenges in the testing procedure, to provide a methodology to obtain the deformation characteristics of basalt bedrock with argillaceous interlayers under dry and wet conditions, to validate the suitability of the test setup and to obtain reliable results. The study also enabled elaborate design and cost savings.