Simplified excavation-induced lateral displacement assessment in Sydney area

Excavations change the stress state of the in-situ ground. The altered stress state causes lateral and vertical displacement in the buildings and structures adjacent to the excavation. In areas like the Sydney region, tectonic locked-in horizontal stresses at shallow depth exceed the vertical stress and the high in-situ horizontal stresses cause possibility of excavation-induced displacement in good quality rocks (e.g., Hawkesbury Sandstone Class I, II, and III). This paper estimates the magnitude and shape of the excavation-induced displacement trough along the excavation edge in Hawkesbury Sandstone. A parametric study was undertaken using three-dimensional finite element analysis to estimate the maximum lateral excavation-induced displacement as well as the lateral displacement trough as a function of the ground type, excavation depth and width, and principal in-situ stress orientation. The results were verified by comparing with monitoring results published for Sydney Sandstone.