Wall element for an underground gallery

A wall element for an underground gallery, comprising a W-shaped member having a height extending along a Y-axis and a width extending along an X-axis, said W-shaped member being formed so that it is symmetrical relative to the Y-axis and its axis of gravity coincides with the X-axis and lies at least approximately in a center of its height, said W-shaped member having bent away lateral flange portions, one central and two outer base portions, and two inner and two outer connecting web portions with different thicknesses, the width of said W-shaped member being considerably greater than the height thereof, and the thicknesses of said portions being selected so that, in relation to used weight per meter, said W-shaped member has a maximum possible moment of resistance relative to the X-axis and a maximum possible bending load capacity in a plastic deformation region, said W-shaped member having such a profile and such thicknesses of said portions that said W-shaped member has at least approximately equal bending load capacity in the plastic deformation region in two opposite directions along the Y-axis, each of said flange portions being curved in a hook-like manner, said central base portion having a width which exceeds the width of each of said outer base portion, each of said base portions having an approximately identical thickness over a greater part of its width and being somewhat convex outwardly in direction of the Y-axis, each of said inner connecting web portions having a reversing point at the height of said X-axis and a thickness increasing from said reversing point in opposite directions toward said base portions, and each of said outer connecting web portions having a center with a thickness exceeding the thickness of said inner connecting web portions and being inwardly curved, and also having a thickness increasing from a respective one of said flange portions toward a respective one of said base portions.