Passage IV
The soil beneath a heavy structure can fail (crack or flow). Adding wires to a soil produces a mixture with a greater compressive strength than that of the soil alone. (Compressive strength is the minimum downward pressure that will cause a material to fail.)
Mixtures of Soil X and 1 mm diameter steel wires were tested for compressive strength. All the wires in a mixture had the same length (1 cm, 2 cm, or 3 cm) and the same angle (90°, 120°, 150°, or 180°, as shown below).
Figures 1, 2, and 3 show how the compressive strength of the mixtures with 1 cm, 2 cm, and 3 cm wires, respectively, varied with wire angle and with the percent by mass of the wires.
Diagram and figures adapted from Amir Kalhor, “Effect of Metal Fibers on Clayey Soils.” ©2008 by Electronic Journal of Geotechnical Engineering.
25. In Figure 1, consider the compressive strength of the mixture containing 0.75 percent by mass of 1 cm wires with an angle of 180°. Would a downward pressure of 160 kPa cause this mixture to fail?
Your Answer is
Correct Answer is D
Explanation
When 0.75% in Figure 1 is at 180°, the compressive strength is less than 160, so it cannot withstand 160kPa, so choose D