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LECTURE 1 AMJ20504 Flipbook PDF







Soil Mechanics Geotechnical Engineering A Historical Perspective

Salwa Binti Mohd Zaini Makhtar

Address: Faculty of Civil Engineering Technology

Contact Numbers: HP : 019-3821957

Email Address: [email protected]

Semester 2 2021/2022

Geotechnical Engineering - A Historical Perspective

Learning Objectives • Define soil, soil mechanics, and geotechnical engineering. • Discuss various historical eras of soil mechanics such as: • • • • •

Prior to the 18th Century Preclassical Period Classical Soil Mechanics Phase 1 Classical Soil Mechanics Phase 2 Modern Soil Mechanics

• Highlight some of the pioneers of modern soil mechanics.

Introduction • For engineering purposes, soil is defined as the uncemented aggregate of mineral grains and decayed organic matter (solid particles) with liquid and gas in the empty spaces between the solid particles. • Soil mechanics is the branch of science that deals with the study of the physical properties of soil and the behavior of soil masses subjected to various types of forces. • Geotechnical engineering is the subdiscipline of civil engineering that involves natural materials found close to the surface of the earth.

Geotechnical Engineering Prior to the 18th Century

Preclassical Period of Soil Mechanics • The natural slopes of soils when tipped in a heap were first studied for formulating the design procedures of retaining walls by Henri Gautier (16601737). • Bernard Forest de Belidor (1671-1761) published a textbook proposing a theory for lateral earth pressure on retaining walls. • The first laboratory model test results on a retaining wall built with sand backfill were reported by Francois Gadroy (1705-1759) in 1746.

Classical Soil Mechanics – Phase 1 (1776-1856) • Most of the developments in geotechnical engineering came from engineers and scientists in France. • In 1776, Charles Coulomb (1736-1806) used the principles of calculus to determine the true position of the sliding surface in soil behind a retaining wall using the laws of friction and cohesion for solid bodies. • Coulomb’s theory was used by many other to study cases such as inclined backfills, backfills supporting surcharge, and determining the magnitude of lateral earth pressure.

Classical Soil Mechanics – Phase 2 (1856-1910) • Henri Darcy (1803-1858) studied the permeability of sand filters and defined the term coefficient of permeability (or hydraulic conductivity) of soil. • Sir George Darwin (1845-1912) conducted laboratory tests to determine the overturning moment on a hinged retaining wall. • Joseph Boussinesq (1842-1929) developed the theory of stress distribution under load bearing areas in a homogenous, semi-infinite, elastic, and isotropic medium.

Modern Soil Mechanics (1910-1927) • Albert Atterberg (1846-1916) defined clay-size fractions as the percentage by weight of particles smaller than 2 microns in size. • Arthur Bell (1874-1956) developed relationships for lateral pressure and resistance in clay as well as bearing capacity of shallow foundations in clay. • Karl Terzaghi developed the theory of consolidation for clays as we know today. He is known as the father of modern soil mechanics.

Geotechnical Engineering after 1927 • The first conference of the International Society of Soil Mechanics and Foundation Engineering (ISSMFE) was held at Harvard University in 1936 with Karl Terzaghi presiding. • Some of the topics brought to the conference include: • • • • • •

Effective stress Shear strength Testing with Dutch cone penetrometer Consolidation Centrifuge testing Elastic theory and stress distribution

Geotechnical Engineering after 1927 • By the early 1950s, computer-aided finite difference and finite element solutions were applied to various types of geotechnical engineering problems. • The dominance of numerical modeling for sophisticated projects with complex boundary conditions will continue for decades to come. • The American Society for Testing and Materials provides standards that cover a wide range of materials which include soils, rocks, and aggregates.

End of an Era • History will remember Karl Terzaghi, Arthur Casagrande, Donald Taylor, Alec Skempton, and Ralph Peck as the pioneers of modern soil mechanics. • The last of the early giants of the profession, Ralph Peck, passed away in 2008 at the age of 95.

Summary • We defined soil, soil mechanics, and geotechnical engineering. • We provided a history of some major advancements in the field of soil mechanics. • We highlighted some of the pioneers of modern soil mechanics.