Question

The suction head ____________ capillary head in vacuum method of dewatering.

(a) should be greater than

(b) should be less than

(c) should be equal to

(d) does not depend on

I got this question during an interview for a job.

This interesting question is from Drainage and Dewatering topic in chapter Drainage and Dewatering of Geotechnical Engineering I

Answer 1

Right choice is (a) should be greater than

To explain I would say: In vacuum method, it is necessary to apply a suction head in excess of the capillary head to the dewatering system. This is important so as to facilitate the creation of vacuum in the sand filling.