Soil improvement in its broadest sense is the alteration of any property of a soil to improve its engineering performance. This may be either a temporary process to permit the construction of a facility or may be a permanent measure to improve the performance of the completed facility. The result of an application of a technique may be increased strength, reduced compressibility, reduced permeability, or improved ground water condition.

Foundation
Foundation is the part of structure below plinth level up to the soil. It is in direct contact of soil and transmits load of super structure to soil. Generally it is below the ground level. If some part of foundation is above ground level, it is also covered with earth filling. This portion of structure [...]

EARTHQUAKE HAZARDS RELATED TO GEOTECHNICAL ENGINEERING

•         Ground Shaking: Shakes structures constructed on ground causing them to collapse

•         Liquefaction: Conversion of formally stable cohesionless soils to a fluid mass, causing damage to the structures

•         Landslides: Triggered by the vibrations

•         Retaining structure failure: Damage of anchored wall, sheet pile, other retaining walls and sea walls

•         Fire: [...]

Lateral Deformation and Spreading

Lateral Spreading: Liquefaction related phenomenon

Upslope portion of lateral spread at Budharmora, Gujarat

Lateral spreading in the soil beneath embankment causes the embankment to be pulled apart, producing the large crack down the center of the road.

Cracked Highway, Alaska, 1964

Lateral Deformation and Spreading

Ø  Down slope movement of soil, when loose sandy [...]

Earthquake Destruction: Fire

Earthquakes sometimes cause fire due to broken gas lines, contributing to the loss of life and economy.

The destruction of lifelines and utilities make impossible for firefighters to reach fires started and make the situation worse

eg.    1989 Loma Prieta

        1906 San Francisco

Earthquake Destruction: Tsunamis

Tsunamis can be generated when the sea floor [...]

Ground Improvement for Liquefaction Hazard Mitigation

Ground Improvement in IS Code

        “In poor and weak subsoils, the design of conventional shallow foundation for structures and equipment may present problems with respect to both sizing of foundations as well as control of foundation settlements. Traditionally, pile foundations have been employed often at enormous costs. A more [...]

A soil mass consists of solid particles which form a porous structure. The voids in the soil mass may be filled with air, water or partly with water and partly with water. Soil is a three phase system in general.

VOLUMETRIC RELATIONSHIPS
Void Ratio
Void ratio is the volume of voids to the volume of solids. [...]

Soils are the fundamental resource supporting agriculture and forestry, as well as contributing to the aesthetics of a green planet. They are also a base from which minerals are extracted and to which solid wastes are disposed. In addition, soils act as a medium and filter for collection and movement of water. By supporting plant [...]

When a soil mass is subjected to a compressive force, its volume decreases. The property of the soil due to which a decrease in volume occurs under compressive force is known as the compressibility of soil. The compression of soil can occur due to

Compression of solid particles and water in the voids
Compression and expulsion of [...]

Compaction means pressing of soil particles close to each other by mechanical methods. Air during compaction is expelled from the void space in the soil mass and therefore the mass density is increased. Compaction is done to improve the engineering properties of the soil. Compaction of soil is required for the construction of earth [...]

The following tests are used to measure the shear strength of the soil

Direct shear test

Triaxial compression test

Unconfined compression test

Vane shear test

Depending upon the drainage conditions, there are three types of tests

Unconsolidated-Undrained condition

Consolidated – Undrained condition

Consolidated-Drained condition

DIRECT SHEAR TEST
Apparatus
The test is conducted in a soil specimen in a shear box which is split in to two [...]

Residential Foundation Problems
Foundation Design:

Ideally, a properly designed and constructed residential foundation is designed to accommodate the weight of the structure, as well as the load bearing characteristics of the soils below. It should also be laid on undisturbed, native soil.

Continuous or “spread” footings should be cast along the base of walls when soils [...]

Braced Walls or (mostly) strut support

Soldier pile and lagging walls with anchor or strut support
Sheet piling or sheet pile walls with anchor or strut support
Pile walls (contiguous, secant) with anchor or strut support
Diaphragm walls or slurry trench walls with anchor or strut support
Prefabricated diaphragm walls with [...]

The process of consolidation is often confused with the process of compaction. Compaction increases the density of an unsaturated soil by reducing the volume of air in the voids (see Fig.1). However, consolidation is a time-related process of increasing the density of a saturated soil by draining some of the water out of the [...]

Caisson Foundation

The foundation system of and the soils beneath the building prevent the complex from moving vertically.

When a load is placed on soil, most soils settle. This creates a problem when the building settles but the utilities do not. Even more critical than settlement is differential settlement.

This occurs when parts of your building [...]

Reinforced earth is a composite material formed by the friction between the earth and the reinforcement. By means of friction the soil transfers to the reinforcement the forces built up in the earth mass. The reinforcement thus develops tension and the earth behaves as if it has cohesion.
COMPONENTS OF REINFORCED EARTH

SOIL
SKIN
REINFORCEMENT

SOIL FOR REINFORCED EARTH

Development of [...]