Device for supporting a gallery or a tunnel

A method for supporting a gallery or tunnel having a mining face being cut by a mining machine, using provisional and permanent support frames, said provisional frames each including a U-shaped assembly having two legs and which can be reduced in size, said method comprising:

• laying out between the mining machine and the mining face a plurality of floor girders extending transverse to the longitudinal dimension of the tunnel and releasably connecting the legs of a plurality of provisional support frames to the ends of respective floor girders;
• disconnecting the legs of one of said provisional support frames which is situated at the greatest distance from the mining face from its respective floor girder;
• reducing the size of such frame;
• passing the reduced frame through at least one previously expanded second provisional support frame which has its legs releasably connected to the ends of a floor girder;
• releasably connecting the legs of the reduced support frame to a floor girder near the mine face and expanding such frame;
• and connecting the lower ends of the legs of a permanent U-shaped support frame to a floor girder from which a provisional support frame was disconnected.