Question

The angle of internal friction for fines lesser than 5% is ___________

(a) φ=25+0.15 ID

(b) φ=20+0.15 ID

(c) φ=15+0.15 ID

(d) φ=10+0.15 ID

I had been asked this question in an international level competition.

The origin of the question is Geophysical Methods in chapter Stabilisation of Soils, Site Investigation and Sub – Soil Exploration of Geotechnical Engineering II

Answer 1

Correct answer is (b) φ=20+0.15 ID

Best explanation: Meyerhof in 1956 gave approximate values of φ with respect to density index ID. For fines lesser than 5%, the general formula is,

φ=20+0.15 ID

where, φ=angle of internal friction

 ID= density index.