Arrangements used for shoring excavations in the ground

In a tunnel lining and excavation shoring system of the type having a plurality of substantially parallel spaced-apart trusses spaced from and substantially parallel to the surface to be shored, and metal plating unit attached to and spanning the spaces between said trusses, the space between said plating unit and the surface to be shored being adapted to later filling with concrete, the improvement of a modular plating unit comprising:

• (a) said plating unit being fabricated of pressed steel;
• (b) said plating unit having parallel trapezoidal longitudinal channels therein;
• (c) a row of alternating convex and concave trapezoidal shapes between each pair of parallel trapezoidal longitudinal channels, the apices of said convex and concave trapezoidal shapes being parallel and being located in spaced-apart imaginary planes;
• (d) the junction of the walls and apices of said trapezoidal longitudinal channels and said alternating convex and concave trapezoidal shapes being straight and comprising lines for action as flexing points;
• (e) windows between adjacent concave and convex trapezoidal shapes;
• and
• (f) said windows reducing the length of one of said concave and convex trapezoidal shapes.