Managing hydrogeological risks in underground construction

Licentiate thesis, 2021

Groundwater leakage into underground constructions can cause groundwater drawdown and subsequently costly damages to objects impacted by changes in groundwater conditions. In order to reduce the damage risk, risk-reducing measures can be implemented. When implementing measures, society’s limited resources must be carefully managed by balancing the costs and the benefits (e.g. reduced risk) of the measures. Decisions regarding risk-reducing measures must always be taken under uncertainty since the conditions of the hydrogeological system cannot be fully known. In this thesis, a generic framework for management of hydrogeological risks in underground construction is presented (Paper 1). This framework constitutes a structured and transparent approach to the decision process for implementation of risk-reducing measures for groundwater control in underground construction. The framework uses a stochastic and iterative approach for managing the changing level of uncertainty inevitably associated with underground construction. The different modules that constitute the framework are also exemplified by application in a case study (paper 2). The case study focuses on the risk of subsidence damages to the built-up environment (buildings, paved surfaces and pipes) and risk-reducing measures in the form of sealing, artificial recharge and reinforcement measures to houses. The framework and methods used within the framework for the risk analysis and risk evaluation have proven useful as decision support for management of hydrogeological risks. The framework has also proven to be an efficient tool in communication of risks both internally in a project but also between the project owner and stakeholders in the society.