Ground Improvement Techniques MCQ with answer and solution

Concept

Electro-osmotic Dewatering

Step-by-step solution

1. Review the given question about where the electro-osmosis ground water control technique is most effectively used. 2. Recall that electro-osmosis uses an electric gradient to move pore water in low-permeability, fine-grained soils (silts and clays) where normal hydraulic drainage fails. 3. Compare with the options and select Option (c) as the correct choice.

Explanation

Electro-osmosis uses an electric current to move pore water through fine-grained soils like silts and clays, which have extremely low permeability and cannot be effectively drained using standard hydraulic pumping methods.

Shortcut

To remember Electro-osmosis application, use the phrase "Electro = Electricity for Fine Clays": - Electric Flow: Uses electric current to move water when normal hydraulic flow fails. - Fine Soils: Most effective in fine-grained soils (silts and clays) with low permeability.

Common mistake

A common mistake is selecting option A by confusing electro-osmosis with conventional dewatering methods (like sump pumping or wellpoint systems), which work best in coarse, highly permeable soils like gravel and sand. In reality, electro-osmosis is specifically employed when hydraulic permeability is too low for standard pumping, making it ideal for fine-grained silts and clays. Another frequent mistake is selecting option D by misunderstanding the purpose of electro-osmosis as soil moistening rather than groundwater drainage.