Patent ID: 8920074
Filing Date: 2014-12-30
Classification: E21D

Abstract:
1. An underground working apparatus comprising a working head of a non-circular cross-section in a direction of travel for moving through underground material and forming a non-circular cross-sectional passageway behind the working head as it advances through the underground material, an elongate structure extending through the non-circular cross-sectional passageway to the working head, and means for positioning a shroud assembled from a plurality of longitudinal shroud sections, wherein each of the plurality of longitudinal shroud sections are formed from a compacted longitudinal shroud section about at least a portion of a longitudinal periphery of the elongate structure as the non-circular cross-sectional passageway is formed for supporting engagement with a periphery of the non-circular cross-sectional passageway to support and provide a space corresponding to the non-circular cross-sectional passageway through which the elongate structure can move as the shroud is positioned, the shroud having a cross-sectional shape corresponding generally to a non-circular cross-sectional shape of the non-circular cross-sectional passageway formed by the working head when the shroud is deployed in the non-circular cross-sectional passageway, wherein each of the plurality of shroud sections corresponds to a side of the non-circular cross-sectional passageway when in place, and wherein the supporting engagement of the shroud maintains the non-circular cross-sectional shape of the non-circular cross-sectional passageway and space so that the non-circular cross-sectional passageway does not collapse.