THEORY EXAMINATION (SEM–VIII) 2016-17 GROUND IMPROVEMENT TECHNIQUES

SECTION – A

Explain the following (Short Answer Type)

Soil stabilization is the process of improving soil strength and stability by adding materials such as lime, cement, or chemicals. It is used to increase load-bearing capacity and reduce settlement.

Field methods of compaction include rolling, tamping, vibration, and dynamic compaction, which help increase soil density.

Vibro compaction is used to densify loose granular soils such as sand and gravel to improve bearing capacity.

In-situ densification refers to improving soil density at the construction site without removing soil.

Factors affecting densification in cohesive soils include moisture content, soil type, and compaction energy.

Dewatering removes groundwater from soil to improve stability. Its advantages include improved strength, while disadvantages include soil settlement and cost.

Grouting is the process of injecting fluid material into soil to fill voids and improve strength. It is used for leak prevention and foundation stabilization.

Preloading is adopted when soil needs consolidation before construction to reduce future settlement.

Suspension grouts contain solid particles, while solution grouts consist of chemical solutions that harden after injection.

Geotextiles act as filters by allowing water flow while preventing soil particle movement.

Questions (Section A)

What is soil stabilization?

List field compaction methods.

Define grouting.

What is preloading?

What is the function of geotextiles?

SECTION – B

Attempt any five (Long Answer Type)

Soil-lime stabilization improves clay soil strength by reducing plasticity and increasing durability. It is widely used in road construction.

Dynamic compaction uses heavy weights dropped from height to densify soil. It is effective for deep soil improvement.

Vibro-flotation uses vibrating probes to densify granular soils and improve load-bearing capacity.

Vertical drains with preloading accelerate soil consolidation by allowing water to escape faster.

Thermal stabilization involves heating soil to reduce moisture and improve strength.

Grouts include cement grout, chemical grout, and bitumen grout, each with different properties. Grouting improves soil strength and reduces permeability.

Granular piles are constructed by replacing weak soil with compacted granular material to increase load capacity.

Geosynthetics protect soil by acting as filters, separators, and reinforcement materials.

Questions (Section B)

Explain soil-lime stabilization.

What is dynamic compaction?

What is vibro-flotation technique?

What are types of grouts?

What is the role of geosynthetics?

SECTION – C

Attempt any two (Detailed Explanation)

Soil-cement stabilization involves mixing cement with soil to increase strength and reduce permeability. Factors affecting strength include cement content, moisture, and curing conditions.

Terra probe compaction improves deep soil density by using vibrating probes to rearrange soil particles.

Soil nailing is used to stabilize slopes by inserting steel bars into soil. It is adopted when soil requires reinforcement.

Geosynthetics are used for separation to prevent mixing of different soil layers and improve stability.

Dewatering techniques in cohesive soils include well points, deep wells, and vacuum dewatering methods.

Questions (Section C)

What is soil-cement stabilization?

Explain soil nailing technique.

What are dewatering methods?