Managed Pressure Drilling From Underground

Abstract

This paper is concerned with the use of managed pressure drilling (MPD) in civil engineering applications. The purpose of this is to permit drilling from below the water table while avoiding problems of uncontrolled water and soil outflow from the borehole and in preventing liquefaction of the ground around the borehole. The application discussed is of drilling through a tunnel lining into unconsolidated ground for the purpose of injecting grout to consolidate the soil so that cross passages may be excavated from tunnel to tunnel. The technique could also be used for drilling below the water table through sheet piled walls for the purpose of installing anchors.