The Disturbance Factor of Hoek-Brown Failure Criterion in Dam Foundations

Dam engineers frequently utilize the Hoek-Brown failure criterion for estimating foundation parameters of highly jointed rock masses. An integral component of this criterion, the disturbance factor, is used to assess the effects of blasting and stress relief on rock masses. Defining this strength reduction parameter has been a long-running issue in dam engineering practices. While some preliminary guidelines for determining disturbance factors in open-pit mining, tunnels, and slope applications are available in existing literature, clear guidance specific to dam foundations, where conventional mechanical excavation or controlled blasting techniques are employed, remains limited. In this paper, it is (1) investigated the effects of disturbance on dam foundations, highlighting deviations from other engineering practices, (2) developed a comprehensive dataset that establishes correlations between rock mass properties, disturbance types, and assigned disturbance factors in many dams, and (3) evaluated the influence of disturbance factors on dam design through a classical stability analysis. Incorporating these findings with field observations of disturbance effects on dam foundations, a preliminary guideline is proposed for dam engineers to identify an appropriate range of disturbance factors for their projects.