A long retaining wall is braced by wood shores set at an angle of 30° and supported by concrete thrust blocks, as shown in the first part of the figure. The shores are evenly spaced, 3 m apart.
For analysis purposes, the wall and shores are idealized as shown in the second part of the figure. Note that the base of the wall and both ends of the shores are assumed to be pinned. The pressure of the soil against the wall is assumed to be triangularly distributed, and the resultant force acting on a 3-meter length of the wall is F = 190 kN.
If each shore has a 150 mm × 150 mm square cross section, what is the compressive stress σc in the shores?

Soil Retaining wall Concrete Shore thrust block I1 0.5 m 4.0 m