Selection of Rock Mass Design Parameters for Assessing Excavation Induced Movements in the Sydney CBD

摘要

Deep basement excavations in the Sydney CBD often involve the assessment of lateral groundrnmovements caused by relief of the relatively high horizontal stresses in the Sydney Basin HawkesburyrnSandstone. This task would seem relatively easy because of all the knowledge gathered on this topicrnsuch as rock design parameters, in-situ stress condition and field measurements providing guidancernon expected movements. However, it seems that putting all these information together is not a straightrnforward task and often numerical models fail to reasonably predict movements within thosernexperienced in the field. A simple numerical example is used to illustrate this difficulty which basicallyrnarises from blindly applying the existing knowledge of the Hawkesbury Sandstone geomechanicalrnbehaviour. In this paper, the published rock mass parameters of Hawkesbury Sandstone together withrnsome additional considerations on anisotropy and stress paths are discussed in relation to how theyrnmay affect the numerical predictions.