Soil Mechanics

Liquid limit of inorganic soil not of volcanic organic rarely has a value greater 100 %. Organic soil has a generally high value of liquid limit (liquid limit>50%) but their plastic limit is also comparatively high, hence their plastic index values are not as high as its liquid limit.

The soil which shows a large decrease in its volume due to an increase in its water content without any increase in external pressure or load is termed as collapsible soil. Ex- Loess soil, Sand Dunes, Fine sand & Silt silty cemented due to the presence of calcium. And the properties of collapsible soil is called collapsibility.

Sensitivity is defined as the ratio of Unconfined Compressive Strength in an undisturbed natural state to Unconfined Compressive Strength of soil in the remolded state.

Consistency Index is defined as the ration of the difference of liquid limit and natural water content to the plasticity index. Toughness Index is a ratio of IP & IF.

Shrinkage Index is the range of consistency in which soil is in a semi-solid state of consistency. It is defined as numerical difference of plastic limit & shrinkage limit.

Shrinkage Limits is defined as maximum water content at which reduction in the water content of soil does not lead to reduction in the volume of soil.

Plastic Limits is defined as the minimum water content at which soil is in the plastic stage of consistency or behaves like a plastic material. At plastic limit soil passes plastic state of consistency to a semi-solid state of consistency & visa-versa.

Liquid Limits are defined as the minimum water content at which soil has a tendency to flow. At liquid limit soil passes liquid state of consistency to plastic state of consistency & visa-versa.

Consistency of Soil is the relative ease with which soil can be deformed. It is used generally for fined-grained soil-related large water content.

The result of the particle size distribution analysis is reported in the form of a curve termed as particle size distribution curve. in which % finer is expressed on Y- axis &size of particle is expressed on X- axis on log scale. This curve helps in analysis the type of soil & gradation of soil.

Particle size distribution analysis or mechanical analysis is carried out in two systems: Sieve Analysis, Sedimentation Analysis. In Coarse Grained Soil : we study Gravel & Sand and In Fine Grained Soil: we study Silt & Clay.

Test of unit weight of soil can be determined using the following methods: Water Displacement Method, Submerged Mass Density Method, Core Cutter Method, Sand Replacement Method.

Test of specific gravity can be computed using 50 ml density bottle,500ml flask or pycnometer. Density bottle method is accurate & suitable for all soil.

Interrelationship Between Voids ratio (e), Water Content (w), Specific Gravity (G), Degree of Saturation(s), Dry Unit Weight ,Unit Weight of Water, etc

Relative compaction is defined as the ratio of the dry unit weight of soil in the natural state to the dry unit weight of soil in the densest state. it can applied for both cohesionless &cohesive soil.

It is defined as the ratio of the difference between the void ratio of soil in the loosest state & natural state to the difference in the void ratio of soil in the loosest state & densest state.

Specific Gravity is the ratio of the weight of a given volume to the weight of standard fluid (water) of the same volume. It is represented as ‘G’. It is the Unit less. There are two types of specific gravity: True/Absolute Specific Gravity and Mass/Bulk/Apparent Specific Gravity

Unit Weight is the ratio of weight to volume. It is also known as the specific weight. And Density is the ratio of Mass to volume.

Degree of Saturation is defined as the ratio of the volume of water to the volume of voids present in a given soil mass. It is represented as ‘s’.