Abstract: A gantry support for supporting a roof of a passage is advanceable along a floor of the passage. The support has two parallel supporting elements mutually spaced apart laterally of the support, each element including at least two pairs of frames provided with articulated tracks. One frame of each pair is an upper frame and the other is a lower frame, the tracks of which are adapted to be applied respectively against the roof and floor of the passage by loading jacks applying a spreading force between the upper and lower frames. An intermediate upper frame is carried by an upper cross-member extending from one supporting element to the other and at least one loading jack applying a spreading force connects each lower frame to the corresponding end of the upper cross-member.