# Geotechnical Engineering

CIVIL ENGINEERS ARE IN THE MIDST of a construction revolution. Heavy structures are beingÃ‚Â located in areas formerly considered unsuitable from the standpoint of the supporting power ofÃ‚Â the underlying soils. Earth structures are contemplated that are of unprecedented height and size;Ã‚Â soil systems must be offered to contain contaminants for time scales for which past experience is eitherÃ‚Â inadequate or absent. Designs must be offered to defy the ravages of floods and earthquakes that soÃ‚Â frequently visit major population centers.
All structures eventually transmit their loads into the ground. In some cases this may be accomplishedÃ‚Â only after circuitous transfers involving many component parts of a building; in other cases, such asÃ‚Â highway pavements, contact is generally direct. Load transfer may be between soil and soil or, as inÃ‚Â retaining walls, from soil through masonry to soil. Of fundamental importance is the response that canÃ‚Â be expected due to the imposed loadings. It is within this framework thatÃ‚Â geotechnical engineeringÃ‚Â isÃ‚Â defined asÃ‚Â that phase of civil engineering that deals with the state of rest or motion of soil bodies under theÃ‚Â action of force systems.

## Weight and Mass Relationships of soil

The water content (or moisture content), denoted w, is the only relationship involving weights or masses. It is the ratio […]

## WeightVolume Problems Involving Defined Quantities of soil

Weight-volume problems may be divided into two categories: those where there is a defined quantity of soil, and those where the

## WeightVolume Problems Involving Only Relationships

If only relationships (e.g., void ratio or unit weight) are given, the quantity of soil is indefinite and only other

## Volume Relationships of soil

Volume relationships include the void ratio, the porosity, and the degree of saturation. The void ratio, denoted e, is the

## Unit Weight of soil

The ratio of the weight of a material to its volume is its unit weight, sometimes termed specific weight or

## The Unified Soil Classification System (USCS)

The Unified Soil Classification System is based on the airfield classification system developed by A. Casagrande during World War II.

## The Phase Diagram

In a typical volume of soil the three components are arranged in a complex mixture. To visualize the relationships among the

## The AASHTO Classification System

The AASHTO system classifies soils into seven primary groups, named A-1 through A-7, based on their relative expected quality for

## Specific Gravity of soil

To facilitate working problems across different sets of units, it is convenient to express the unit weight and density of

## Soil problems Weight, Mass, Volume

Example 15.4 Assume that a compaction mold having a volume of 1/30 ft3 was filled with moist soil. The total

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