Introduction to Soil Mechanics

!CHAPTER 1

Introduction Soil:

o natural resource o provide food o shelter o construction material o support for structures o many more..

Soil was used historically o In ancient periods people practiced building on solid/stable

foundations. No theoretical basis for design, trial and error experience.

Coulomb (1773) used soil mechanics principles to protect fortresses from cannon fire. !!!!!!!

He realized that wedge ABC applied lateral force that could topple the fortress

He improved the soil friction on plane BC

Rapid growth in the industry (20th century) required more stable and economic foundations of the civil engineering facilities

Karl Terzaghi published Erdbaumechanik (1925) in which he laid foundation for soil mechanics and showed the importance of soils in the engineering. !

Soil mechanics is subset of Geotechnical Engineering !

Used in the analysis and design design of geotechnical systems such as:

!o Dams o Tunnels o Canals and waterways o Foundations for bridges, buildings o Roads o Solid waste disposal o etc

Dams

Embankments

Tunnels

Bridge Foundations

Building Foundations

Roads

Waste Disposal

Approximate Calculations: !

o Every application of soil mechanics involves uncertainty because of the variability of soils !

o Many of the calculations in soil mechanics are not exact but approximate values !

o Experience and approximate calculations are important for successful application of soil mechanics

Uncertainties of soils performance may make a geotechnical engineer to compromise between sophisticated and simple analyses. !

Stability, however, should never be compromised for economy.

Geotechnical engineers work are often invisible after completion of construction !

However, structural and architectural beauty of buildings would not exist if the foundation of the building is not designed satisfactorily

No matter how well structurally the buildings, roads, airports, dams, etc. are designed they will fail if they are not founded on stable soil !

Successful civil engineering is heavily dependent on geotechnical engineering

Some types of failures may be caused by natural hazards, like earthquakes, and may be difficult to prevent o Geotechnical engineers duty must be

directed towards mitigating damage to lives and property

Safe and economic design of structures on soils rely on our ability to do so !

Poor engineering analysis, design, construction and quality control may result in failures => damage lives and property

We learn from failures and try to prevent it in the future !

Much has been added to the understanding about soil behavior since the founding of soil mechanics by Terzaghi in 1925 !

Through research and experience learning is continuing