Question

For the use of vacuum method, the D10 should be __________

(a) 1mm

(b) more than 1mm

(c) more than 0.5mm

(d) less than 0.05mm

I have been asked this question in unit test.

Question is from Drainage and Dewatering in portion Drainage and Dewatering of Geotechnical Engineering I

Answer 1

Right choice is (d) less than 0.05mm

Easy explanation: For successful dewatering, the average effective particles D10 should be smaller than 0.05mm. The vacuum method is applicable for fine, non-cohesive soils like silty sand whose D10 is less than 0.05mm.