Question

Bowel suggested that the increase in φ in plane-strain case can be computed only for φ greater than ____________

(a) 30

(b) 25

(c) 60

(d) 90

This question was posed to me in a national level competition.

Question is taken from General Bearing Capacity Equation: Brinch Hansen’s Analysis in chapter Bearing Capacity of Geotechnical Engineering II

Answer 1

Right option is (b) 25

The best explanation: Bowel suggests that the increase of φ in the equation φ plain strain = 1.1 φ tri axial can be computed only for φ greater than 25°.