Evaluating rock mass disturbance within open-pit excavations using seismic methods: A case study from the Hinkley Point C nuclear power station

Understanding rock strength is essential when undertaking major excavation projects, as accurate assessments ensure both safe and cost-effective engineered slopes. Balancing the cost-safety trade-off becomes more imperative during construction of critical infrastructure such nuclear power stations, where key components are built within relatively deep excavations. Designing these slopes reliant on models, which generally parameterised using estimates properties (e.g. unconfined compressive strength, disturbance) measured prior to commencement works. However, physical process weakens remaining mass. Therefore, model also requires an adjustment for anticipated disturbance. In practice, this parameter difficult quantify a result it often poorly constrained. This can have significant impact final design cost excavation. We present results from passive active seismic surveys, image extent degree disturbance recently excavated at site Hinkley Point C station. Results surveys indicate that primarily confined 0.5 m face. conjunction, monitoring used detected events corresponding fracturing cm-scale event locations in agreement with into suggests low occurred immediately after A ratio velocities recorded before excavations determine required Hoek–Brown failure criterion, we assess magnitude diminishing quickly than expected slope. Seismic methods provide low-cost quick method related mass disturbance, lead reductions large projects.