Geotechnical Engineering Notes Review

A collection of flashcards derived from lecture notes on Geotechnical Engineering, focusing on compaction, soil improvement methods, and relevant equipment.

What is the primary goal of soil improvement in geotechnical engineering?

To alter the soil properties to improve its engineering performance.

What are three approaches when the soil at a site is not appropriate for engineering purposes?

Avoid the soil problem, adapt the design to site conditions, or improve the soil.

What is compaction in geotechnical engineering?

A deliberate process of pressing soil particles tightly together by expelling air from its void space.

What are the intended outcomes of soil compaction?

Increase in shear strength, decrease in compressibility, and decrease in permeability.

What factors determine the amount of densification achieved through compaction?

The amount of energy used, the method of energy application, the type of soil involved, and the water content.

How is dry unit weight related to wet unit weight?

Dry unit weight is computed from the wet unit weight and moisture content using the formula: γd = (γw)/(1+w).

What happens to soil compaction when excessive water is added?

The dry density results in a lesser density.

What is the purpose of a compaction curve?

To determine the maximum dry unit weight (MDD) and optimum moisture content (OMC) of soil.

What equipment is commonly used for laboratory compaction tests?

Base plate, removable collar, mould, and hammer.

What is relative compaction and how is it determined?

Relative compaction is the ratio of the field dry density to the maximum dry density determined in the lab, expressed as a percentage.

What are the different types of compaction equipment used in field compaction?

Smooth wheel rollers, pneumatic tyred rollers, sheep foot rollers, rammers, vibratory rollers, and vibrating plates.

What are some methods for compaction control in the field?

Sand replacement method, core cutter method, rubber balloon method, and intelligent compaction systems.

What is the significance of Proctor compaction tests?

They establish moisture-density relationships for different soil types, crucial for understanding compaction characteristics.

What structural differences occur during dry-side versus wet-side compaction?

Dry-side compaction yields higher strength and lower compressibility; wet-side compaction produces more flexible materials with lower strength.

What factors influence the choice of compaction equipment?

The type of soil to be compacted, degree of compaction required, and space available for compaction.

What is the impact of soil type on compaction efficiency?

Well-graded granular materials generally achieve higher dry unit weights, while uniformly graded sands and clays of high plasticity respond poorly.