The stability of abandoned mine workings in the Maastrichtian Limestones of Limburg, The Netherlands

Abstract Underground mining for limestone as a building stone has been undertaken in Limburg since Roman times. Mining was carried out at shallow depths using the pillar and stall technique and the rock was sawn out to give large blocks which were later cut into a size and shape appropriate for building purposes. Only layers of unjointed uniform rock were mined and mine workings varied between about two and ten metres in height. Some workings can be established to be at least 300 years old. The rock is weak with unconfined compressive strengths generally less than 5 MPa. Stability problems have arisen as the result of pillar collapse and of the inflow into the mine of the clay infilling of vertical solution ‘organ pipes’ which may have intersected the abandoned mines. The paper presents an account of the problems associated with these old mine workings and discusses methods by which the stability of large areas of abandoned workings may be analyzed.