Influence of carbonate content and micro fabrics on the failure strength of the sandy facies of the Opalinus Clay from Mont Terri (Underground Rock Laboratory)

► A relation of micro fabric, failure strength, and carbonate content of Opalinus Clay was identified. ► With increasing carbonate content the failure strength increases, i.e. mechanically more stable. ► In this respect, the sandy facies differs from the shaly facies of the Opalinus Clay.