Advances in tailings dam breach modelling and credible failure mode assessment using the Material Point Method

Recent tailings dam failures underscore the need for better tools to understand and mitigate the potential impacts of such events. The Global Industry Standard on Tailings Management (GISTM), introduced in response to catastrophic tailings dam failures, is an aspirational standard that defines credible failure modes as technically feasible failure mechanisms. This is an excellent first step, however, GISTM does not state which methodology to assess these failure modes. A commonly employed approach that would be considered as industry standard is the Failure Modes and Effects Analysis (FMEA). The FMEA applies rigour to decision making but is still subject to subjectivity, relying on engineering judgement to inform risk. A tool that can be utilised to understand tailings dam failure further and supplement the FMEA process is the Material Point Method (MPM). A numerical method which allows for large strain, as required in breach analysis, with commonly accepted constitutive soil models and relatively limited computational power requirements in comparison to alternative large strain modelling methodologies. Six case studies utilising MPM is presented. The case studies incorporate an array of tailings facility design, location, complexity, lifecycle and regulatory environments, demonstrating how MPM can enhance understanding of the complex challenges. The benefits of utilising MPM with existing guidelines and current industry practices is highlighted, providing lessons learned and recommendations for implementation of MPM into projects. MPM is a tool that can reduce risk and promote better-informed decision-making, furthering the GISTM goal of ‘zero harm to people and the environment with zero tolerance for human fatality.’