GEOTECHNICAL ENGINEERING (SOIL MECHANICS)

Geotechnical Eng’g A Historical Perspective

In Agronomy, soil means

the upper layer of the earth that may be dug or plowed

In Geology,

earth’s crust is assumed to consist of unconsolidated sediments called mantle or regolith

in geotechnical engineering, the term “soil”

defined by the agronomist or the geologist is known as top soil

Soil

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”

was coined by DR. KARL TERZAGHI in 1925 when his book “ERDBAUMECHANIC” on the subject was published in GERMANY.

Soil Mechanics

the application of the laws of mechanics and hydraulics to engineering problems dealing with sediments and other unconsolidated accumulations of solid particles produced by the mechanical and chemical disintegration of rocks, regardless of whether they contain an admixture or organic constituents

Soil mechanics

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.

Soils engineering

application of the principles of soil mechanics to practical problems.

Geotechnical engineering

subdiscipline of civil engineering that involves natural materials found close to the surface of the earth.

18th century

The understanding of geotechnical engineering as it is known today began early in the

Chan dynasty in China (1120 B.C. to 249 B.C.)

• many dykes were built for irrigation purposes.

• There is no evidence that measures were taken to stabilize the foundations or check erosion caused by floods.

Ancient Greek civilization used

isolated pad footings and strip-and-raft foundations for building structures

2700 B.C.

several pyramids were built in Egypt, most of which were built as tombs for the country’s Pharaohs and their consorts during the Old and Middle Kingdom periods.

during the Eastern Han dynasty in 68 A.D

thousands of pagodas were built.

The Leaning Tower of Pisa in Italy

• Famous examples of problems related to soil-bearing capacity in the construction of structures prior to the 18th century

1173 A.D.

when the Republic of Pisa was flourishing and continued in various stages for over 200 years, Construction of the The Leaning Tower of Pisa in Italy began.

15,700 metric tons

The structure weighs of the tower and supported by a circular base having a diameter of 20 m

11 m below

Recent investigations showed that a weak clay layer existed at a depth of about below the ground surface compression of which caused the tower to tilt. It became more than 5 m out of plumb with the 54 m height.

1990

The tower was closed because it was feared that it would either fall over or collapse.

70 metric tons

It recently has been stabilized by excavating soil from under the north side of the tower. About metric tons of earth were removed in 41 separate extractions that spanned the width of the tower

5 degrees

The tower now leans degrees.

Preclassical (1700 to 1776 A.D.)

• Henri Gautier( 1660-1737)

• Bernard Forest de Belidor (1671 1761)

• Francois Gadroy (1705 1759)

• J. J. Mayniel in 1808

• Jean Rodolphe Perronet( 1708 1794)

Henri Gautier( 1660-1737)

 a French royal engineer

 studied the natural slopes of soils in 1717

 The natural slope is what we now refer to as the angle of repose.

 According to this study, the natural slope of clean dry sand and ordinary earth were 31° and 45°, respectively.

 Also, the unit weight of clean dry sand and ordinary earth were recommended to be 18.1 kN/m3 and 13.4 kN/m3(85 lb/ft3), respectively.

 No test results on clay were reported.

Bernard Forest de Belidor (1671-1761)

 published a textbook for military and civil engineers in France

In the book, he proposed a theory for lateral earth pressure on retaining walls that was a follow up to Gautier’s (1717) original study.

Francois Gadroy (1705 -1759)

 a French engineer

 Reported the first laboratory model test results on a 76-mm-high retaining wall built with sand backfill in 1746.

J. J. Mayniel in 1808

Summarized the study of Gadroy

Jean Rodolphe Perronet( 1708-1794)

 a French engineer

 studied slope stability around 1769 and distinguished between intact ground and fills.

Classical Soil Mechanics—Phase I (1776–1856)

(During this period, most of the developments in the area of geotechnical engineering came from engineers and scientists in France. In the preclassical period, practically all theoretical considerations used in calculating lateral earth pressure on retaining walls were based on an arbitrarily based failure surface in soil.)

Classical Soil Mechanics—Phase I (1776–1856)

• Charles Augustin Coulomb(1736-1806)

• Gaspard Clair Marie Riche de Prony ( 1755 1839)

• Jacques Frederic Francais

  ( 1775 1833) and Claude Louis Marie Henri Navier (1785-1836)

• Jean Victor Poncelet( 1788 1867)

• Alexandre Collin( 1808-1890)

• William John Macquorn Rankine( 1820-1872)

Preclassical (1700 to 1776 A.D.)

(This period concentrated on studies relating to natural slope and unit weights of various types of soils, as well as the semi empirical earth pressure theories.)

Charles Augustin Coulomb(1736-1806)

 French scientist

 used the principles of calculus for maxima and minima to determine the true position of the sliding surface in soil behind a retaining wall.

 In this analysis, Coulomb used the laws of friction and cohesion for solid bodies.

Gaspard Clair Marie Riche de Prony (1755-1839)

 French civil engineer

 included Coulomb’s theory in his leading textbook, Nouvelle Architecture Hydraulique (Vol. 1) in 1790

Jacques Frederic Francais (1775-1833) and Claude Louis Marie Henri Navier (1785-1836)

 Studied special cases of Coulomb’s work in 1820

 These special cases related to inclined backfills and backfills supporting surcharge.

Jean Victor Poncelet( 1788 1867)

 an army engineer and professor of mechanics

 extended Coulomb’s theory by providing a graphical method for determining the magnitude of lateral earth pressure on vertical and inclined retaining walls with arbitrarily broken polygonal ground surfaces in 1840.

 he was also the first to use the symbol 𝜙 for soil friction angle. He also provided the first ultimate bearing-capacity theory for shallow foundations.

Alexandre Collin( 1808-1890)

 an engineer

 provided the details for deep slips in clay slopes, cutting, and embankments

 He theorized that in all cases the failure takes place when the mobilized cohesion exceeds the existing cohesion of the soil.

 He also observed that the actual failure surfaces could be approximated as arcs of cycloids

William John Macquorn Rankine( 1820-1872)

 The end of Phase I of the classical soil mechanics period is generally marked by the year (1857) of the first publication by Rankine

 a professor of civil engineering at the University of Glasgow.

 This study provided a notable theory on earth pressure and equilibrium of earth masses. Rankine’s theory is a simplification of Coulomb’s theory.

Classical soil mechanics—Phase II (1856 to 1910 A.D.)

(Several experimental results from laboratory tests on sand appeared in the literature in this phase)

Classical soil mechanics—Phase II (1856 to 1910 A.D.)

• Henri Philibert Gaspard Darcy ( 1803 1858)

• George Howard Darwin( 1845-1912)

• Joseph Valentin Boussinesq( 1842 1929)

• Osborne Reynolds( 1842 1912)

• John Clibborn( 1847- 1938) and John Stuart Beresford (1845- 1925 )

Henri Philibert Gaspard Darcy ( 1803 1858)

 French engineer

 he published a study on the permeability of sand filters in 1856.

 Based on those tests, Darcy defined the term coefficient of permeability (or hydraulic conductivity) of soil, a very useful parameter in geotechnical engineering to this day

George Howard Darwin( 1845-1912)

 professor of astronomy

 Conducted laboratory tests to determine the overturning moment on a hinged wall retaining sand in loose and dense states of compaction.

Joseph Valentin Boussinesq (1842 1929)

 He developed the theory of stress distribution under loaded bearing areas in a homogeneous, semi-infinite, elastic, and isotropic medium in 1885.

Osborne Reynolds( 1842 1912)

 He demonstrated the phenomenon of dilatancy in sand in 1887.

John Clibborn( 1847- 1938) and John Stuart Beresford (1845- 1925 )

 Both studied the flow of water through sand bed and uplift pressure.

 Clibborn’s study was published in the Treatise on Civil Engineering, Vol. 2: Irrigation Work in India, Roorkee in 1901 and also in Technical Paper No. 97, Government of India in 1902.

 Beresford’s 1898 study on uplift pressure on the Narora Weir on the Ganges River has been documented in Technical Paper No. 97, Government of India in 1902.

Modern Soil Mechanics (1910–1927)

(In this period, results of research conducted on clays were published in which the fundamental properties and parameters of clay were established)

Modern Soil Mechanics (1910–1927)

• Albert Mauritz Atterberg( 1846 1916)

• Jean Fontard( 1884- 1962)

• Arthur Langley Bell( 1874 1956)

• Wolmar Fellenius( 1876 1957)

• Karl Terzaghi( 1883 1963)

Albert Mauritz Atterberg( 1846 1916)

 a Swedish chemist and soil scientist

 He defined clay-size fractions as the percentage by weight of particles smaller than 2 microns in size.

 He realized the important role of clay particles in a soil and the plasticity thereof.

 In 1911, he explained the consistency of cohesive soils by defining liquid, plastic, and shrinkage limits.

 He also defined the plasticity index as the difference between liquid limit and plastic limit

Jean Fontard (1884- 1962)

 French engineer

 He investigated the cause of failure of the 17-m-high earth dam at Charmes, France on October 1909.

 In that context, he conducted undrained double-shear tests on clay specimens (0.77 m2 in area and 200 mm thick) under constant vertical stress to determine their shear strength parameters.

 The times for failure of these specimens were between 10 to 20 minutes

Arthur Langley Bell( 1874 1956)

 civil engineer from England

 worked on the design and construction of the outer seawall at Rosyth Dockyard.

 Based on his work, he developed relationships for lateral pressure and resistance in clay as well as bearing capacity of shallow foundations in clay

 He also used shear-box tests to measure the undrained shear strength of undisturbed clay specimens.

Wolmar Fellenius( 1876 1957)

 engineer from Sweden

 developed the stability analysis of saturated clay slopes (that is, Ø = 0 condition) with the assumption that the critical surface of sliding is the arc of a circle.

 These were elaborated upon in his papers published in 1918 and 1926. The paper published in 1926 gave correct numerical solutions for the stability numbers of circular slip surfaces passing through the toe of the slope.

Karl Terzaghi( 1883 1963)

 developed the theory of consolidation for clays

 The theory was developed when he was teaching at the American Robert College in Istanbul, Turkey.

 His study spanned a five-year period from 1919 to 1924. Five different clay soils were used. The liquid limit of those soils ranged between 36 and 67, and the plasticity index was in the range of 18 to 38.

 The consolidation theory was published in Terzaghi’s celebrated book Erdbaumechanik in 1925.

Geotechnical Engineering after 1927

(The publication of Erdbaumechanik auf Bodenphysikalisher Grundlage by Karl Terzaghi in 1925 gave birth to a new era in the development of soil mechanics.)

Karl Terzaghi( 1883 1963)

• father of modern soil mechanics

• born on October 2, 1883 in Prague, which was then the capital of the Austrian province of Bohemia.

• - In 1904 he graduated from the Technische Hochschule in Graz, Austria, with an undergraduate degree in mechanical engineering. After graduation he served one year in the Austrian army.

• - Following his army service, Terzaghi studied one more year, concentrating on geological subjects. In January 1912, he received the degree of Doctor of Technical Sciences from his alma mater in Graz. In 1916, he accepted a teaching position at the Imperial School of Engineers in Istanbul. After the end of World War I, he accepted a lectureship at the American Robert College in Istanbul (1918–1925). There he began his research work on the behavior of soils and settlement of clays and on the failure due to piping in sand under dams. The publication Erdbaumechanik is primarily the result of this research.

Karl Terzaghi( 1883 1963)

• In 1925, Terzaghi accepted a visiting lectureship at Massachusetts Institute of Technology, where he worked until 1929. During that time, he became recognized as the leader of the new branch of civil engineering called soil mechanics. In October 1929, he returned to Europe to accept a professorship at the Technical University of Vienna, which soon became the nucleus for civil engineers interested in soil mechanics. In 1939, he returned to the United States to become a professor at Harvard University.

• 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. The conference was possible due to the conviction and efforts of Professor Arthur Casagrande of Harvard University. About 200 individuals representing 21 countries attended this conference.

End of an Era

(A brief outline of the contributions made to modern soil mechanics by pioneers such as Karl Terzaghi, Arthur Casagrande, Donald W. Taylor, Laurits Bjerrum, and Ralph B. Peck)

RalphB . Peck( 1912 2008)

 He received B.S. and Ph.D. degrees in 1934 and 1937, respectively, from Rensselaer Polytechnic Institute, Troy, New York.

 During the period from 1938 to 1939, he took courses from Arthur Casagrande at Harvard University in a new subject called “soil mechanics.”

 From 1939 to 1943, Dr. Peck worked as an assistant to Karl Terzaghi, the “father” of modern soil mechanics, on the Chicago Subway Project.

 In 1943, he joined the University of Illinois at Champaign–Urban and was a professor of foundation engineering from 1948 until he retired in 1974.

 OnMarch 13, 2008, The Times of the United Kingdom wrote, “Ralph B. Peck was an American civil engineer who invented a controversial construction technique that would be used on some of the modern engineering wonders of the world, including the Channel Tunnel.

RalphB . Peck( 1912 2008)

 Known as ‘the godfather of soil mechanics,’ he was directly responsible for a succession of celebrated tunneling and earth dam projects that pushed the boundaries of what was believed to be possible.”

 Dr. Peck authored more than 250 highly distinguished technical publications. He was the president of the ISSMGE from 1969 to 1973. In 1974, he received the National Medal of Science from President Gerald R. Ford. Professor Peck was a teacher, mentor, friend, and counselor to generations of geotechnical engineers in every country in the world. The 16th ISSMGE Conference in Osaka, Japan (2005) would be the last major conference of its type that he would attend.

 This is truly the end of an era!

Four major period of era

• Preclassical (1700 to 1776 A.D.);

• Classical soil mechanics—Phase I (1776 to 1856 A.D.);

• Classical soil mechanics—Phase II (1856 to 1910A.D.); and

• Modern soil mechanics (1910 to 1927A.D.