Question

In ___________ method, the underpinning is carried out by vibrating the sand.

(a) Cement grouting

(b) Vibroflotation

(c) Chemical consolidation

(d) Freezing

I have been asked this question in class test.

The above asked question is from Underpinning and its Types in chapter Scaffolding, Shoring and Underpinning of Construction & Building Materials

Answer 1

Right choice is (b) Vibroflotation

To explain I would say: Vibroflotation increases the density of soil which ultimately results in the increase of bearing capacity of soil. This method is useful for granular or sandy soil and before the processing of underpinning start, the building or any of its structure components is shored carefully.