"Going underground in quarrying: technical perspectives for marble in Portugal"

This paper examines the application of the criteria for the alternative choice of underground quarrying in ornamental stone. In these quarries, the rock mass quality is usually good, and in most cases exploitation is carried out by means of open pit methods. Underground quarrying in ornamental stones is possible when certain prerequisites are satisfied: geostructural features, stability contraints, land planning, and when the recovery and safety goals are achievable. After a general discussion of these items, the paper analyzes the case of the pink marble of the Alentejo basin in Portugal, in which a first tentative design method and monitoring approach has been proposed. The development of open pit exploitation İn Alentejo has determined the creation of very deep pits from the flat ground surface: in some cases, a depth of one hundred meters has been reached with vertical lateral surfaces.