Principles of Risk-Based Rock Engineering Design

Abstract

In comparison with other types of construction, the development of rock engineering design codes has been slow. Codes must, however, be developed with relevant discipline-specific characteristics in mind. This paper, therefore, presents a generic design framework for rock engineering. The framework is based on the presumption that rock engineering design must be viewed as decision-making under uncertainty, which makes the design process subject to general risk management principles, as risk is defined as "effect of uncertainties on objectives" (ISO 31000). Thus, rock engineering design codes ultimately need to facilitate design processes that target the risk, to enable design of structures that not only are sufficiently safe and durable and cost-effectively constructed, but also imply safe and healthy work conditions during construction and an acceptably low environmental impact. The presented framework satisfies this fundamental requirement and the authors find codification of its principles to be rather straightforward, as long as the level of detail in the code is governed by a strict application of ISO's general risk management principles. Further details on methods and practical recommendations can instead be supplemented in separate handbooks and application guidelines.

Risk management procedure to understand and interpret the geotechnical context

“…Here we provide an overview, but refer to Spross, Olsson, and Stille (2018) for a more extensive discussion of its principles. Its implementation in rock engineering design has recently been discussed by Spross et al (2020a).…”

Principles of structured risk management in rock engineering

“…The most important uncertainty in rock engineering is the difficulty to predict a large-scale behaviour of a jointed rock mass, i.e., the geological scenario, as there is typically only limited information available from for example pre-investigations, smallscale laboratory tests on intact rock, and empirical assessments [18]. Examples of underlying factors to uncertainties include the rock mass composition, tectonic stress conditions, groundwater conditions, as well as influence from excavation features (i.e., size, shape, and rock-support interaction) [19,20].…”

“…Examples of underlying factors to uncertainties include the rock mass composition, tectonic stress conditions, groundwater conditions, as well as influence from excavation features (i.e., size, shape, and rock-support interaction) [19,20]. Spross et al [18] provide a comprehensive table of factors that may contribute with uncertainty to the design work in a rock engineering project.…”

“…Risk identification implies identifying the threats that the external factors may cause and describing how they can lead to consequences; in design work this means identifying the issues that need to be considered in the design. The design issues can be divided into five categories: structural safety, durability, serviceability, environmental impact, and work environment [18]. Table 2 gives some examples of design issues for each category.…”

“…The cyclic work process for risk management. (© Ref [18],. CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)…”