Sequential back analysis of spatial distribution of geomechanical properties around an unlined rock cavern

This paper develops a sequential displacement data collection and back analysis approach for mapping spatially distributed Young's modulus (E) in a rock mass during the excavation of an unlined rock cavern (URC). Results show that this approach provides an unbiased estimate of the E field and its uncertainty. It also reveals a more detailed E distribution than kriging approach, which is based on samples of E values from boreholes before excavations. Further, predicted shear strain distribution and displacement of cavern periphery based on the estimates from this approach are more accurate than those based on the kriging estimate.