Uncertainty quantification of the bond stress – displacement relationship of shoring anchors in different geologic units

ABSTRACT

The design of anchored wall systems is governed by the bond strength between the grout and the surrounding soil/rock in the grouted zone. Published work on the reliability of anchored retaining systems focuses on ultimate limit state considerations to ensure a target level of reliability against pullout of the anchor in the bonded zone. These studies do not shed light on the uncertainty in the bond stress – displacement relationship of the grout/soil interface. This uncertainty exists as a result of spatial variability in the soil/rock properties even within the same geologic unit. The primary objective of this paper is to quantify the uncertainty in the bond stress – displacement relationship to aid the serviceability limit state design of anchored wall systems. To achieve this objective, a database of shoring anchor tests from real projects that were executed in several sites around Beirut is assembled and analysed. The tests are categorised based on three different geologic units (Limestone, Marls, and Clays) that are common to many geologic settings in the world. The bond stress – displacement relationship is modelled with a hyperbolic model and the statistics of the model are derived from the assembled database and classified based on the geologic units analysed.

KEYWORDS:

• Anchor
• pull-out test
• uncertainty
• variability
• deformation
• bond strength
• Clay
• Limestone
• Marl

Acknowledgements

The authors would like to acknowledge the specialty geotechnical contractor Edrafor for providing the authors with access to the results of the anchor pullout tests that were analysed in this paper. The authors would also like to acknowledge the University Research Board (URB) at the American University of Beirut for supporting the research of the authors.

Disclosure statement

No potential conflict of interest was reported by the authors.