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.

22. In Figures 1−3, consider the compressive strengths of the mixtures containing 0.75 percent by mass of wires. For which of the wire lengths was the compressive strength greater for a wire angle of 120° than it was for a wire angle of 90° ?

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

Under the condition of 0.75%, the corresponding value of the vertical axis of 120 degrees is greater than the corresponding value of 90 degrees, only Figure 1 and Figure 3 are consistent, that is, 1cm and 3cm, choose H