Question

Which among the following type of dam section is expected to be the thinnest and the most economical?

(a) Constant angle arch dam

(b) Shell-arch dam

(c) Constant radius arch dam

(d) Concrete gravity dam

I have been asked this question at a job interview.

Question is taken from Arch Dams topic in chapter Arch and Buttress Dams of Irrigation Engineering

Answer 1

Correct answer is (b) Shell-arch dam

Explanation: Shell arch dams are much more economical than the constant angle arch dams as their sections are quite thin. The Idduki dam in India is only 45 m thick at its base even with 170.7 m height whereas the famous Hoover dam of the USA which is a constant radius arch dam is 201m thick at its base with only 222 m in height.