GEOTECH Flashcards
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.
Soil Engineering
is the application of the principles of soil
mechanics to practical problems.
Geotechnical Engineering
is the sub discipline of civil engineering that involves natural materials found close to the surface of the earth. It includes the application of soil mechanics and rock
mechanics to the design of foundations, retaining structures and
earth structures.
18th century
___________ when the understanding of
geotechnical engineering as it is known today began
in true engineering terms (Skempton, 1985).
▪ Ancient civilizations flourished along the banks of
rivers (Nile in Egypt, Tigris and Euphrates in
Mesopotamia, Huang Ho or Yellow river in China and
Indus in India).
▪ There is no evidence that measures were
taken to stabilize the foundations or check
erosion caused by flood (Kensel, 1986).
Leaning Tower of Pisa (Italy)
most famous example of problems related to soil bearing
capacity in the construction of structures.
Construction began in 1173 AD and continued
for over 200 years.
Four major periods in geotechnical engineering based on emphasis
and nature of study
- Pre classical (1700 to 1776 AD)
- Classical Soil Mechanics – Phase 1 (1776 to 1856 AD)
- Classical Soil Mechanics- Phase 2 (1856 to 1910 AD)
- Modern Soil Mechanics (1910 to 1927 AD)
Pre-Classical Soil Mechanics (1700 – 1776)
This period concentrated on studies relating to
natural slope and unit weight of various types of
soils, as well as the semi empirical earth pressure
theories.
Pre-Classical Soil Mechanics (1700 – 1776)
Henri Gaulter (1660-1737)
french royal
engineer, in 1717 studied the natural slopes of
soils when tipped in a heap for formulating the
design procedures of retaining walls.
Pre-Classical Soil Mechanics (1700 – 1776)
Bernard Forest de Belidor (1671-1761)
published a text book in 1729 in France. He proposed a theory for lateral earth pressure on
retaining walls that was a follow up to Gautier’s
(1717) original study.
Pre-Classical Soil Mechanics (1700 – 1776)
Francois Gadroy (1705-1759)
- French engineer, in 1746 the
first laboratory model test results on retaining wall w/ sand
backfill was reported. - Observe existence of slip planes in the soil at failure
Pre-Classical Soil Mechanics (1700 – 1776)
J.J. Mayniel (1808)
Summarizes Gadroy’s study.
Classical Soil Mechanics – Phase 1 (1776-1856)
Charles Augustin Coulomb (1736-1806)
in 1776,
used calculus to determine the true position of the
sliding surface in soil behind a retaining wall. He
used laws of friction and cohesion for solid bodies.
Classical Soil Mechanics – Phase 1 (1776-1856)
▪ Jacques Frederic Francais (1775-1833) and Claude
Louis Marie Henri Navier (1785-1836)
In 1820,
French engineer and french applied mechanics
professor respectively, studied special cases of
Coulomb’s work w/c are related to inclined
Retaining Wall Collapse backfills and backfills supporting surcharge.
Classical Soil Mechanics – Phase 1 (1776-1856)
Jean Victor Poncelet (1788-1867)
army engineer and professor of mechanics, in 1840
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, first to use
the symbol φ for soil friction angle, provided the
first ultimate bearing-capacity theory for
shallow foundations.
Classical Soil Mechanics – Phase 1 (1776-1856)
Alexandre Collin (1808-1890)
In 1846, an
engineer, provided the details for deep slips in
clay slopes, cutting and embankments.
Classical Soil Mechanics – Phase 1 (1776-1856)
William John Macquorn Rankine (1820-1872)
In 1857, professor of civil engineering at the
University of Glasgow published a study in w/c
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 2 (1856-1910)
Henri Philibert Gaspard Darcy (1803-1858)
French
engineer, in 1856 published a study on permeability of
sand filters.
Classical Soil Mechanics – Phase 2 (1856-1910)
Sir 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.
Classical Soil Mechanics – Phase 2 (1856-1910)
Joseph Valentin Boussinesq (1842-1929)
In 1885, he
published the development of the theory of stress
distribution under loaded bearing areas in a
homogeneous, semi-infinite, elastic, and isotropic medium.
Classical Soil Mechanics – Phase 2 (1856-1910)
Osborne Reynolds (1842- 1912)
In 1887, demonstrated
the phenomenon of dilatency in sand.
Modern Soil Mechanics (1910-1927)
Albert Mauritz Atterberg (1846-1916)
a Swedish chemist and soil scientist, explained the consistency of cohesive soils by defining liquid, plastic and
shrinkage limits and also defined plasticity index as the difference between
liquid limit and plastic limit.
Modern Soil Mechanics (1910-1927)
Jean Fontard (1884-1962)
carried out an investigation on the cause of
failure of a high earth dam in France in 1909. He conducted an undrained
double shear test on clay specimens to determine shear strength parameters.
Modern Soil Mechanics (1910-1927)
Arthur Langley Bell (1874-1956)
Civil Engineer from England, developed
relationships for lateral pressure and resistance in clay as well as bearing
capacity of shallow foundations in clay.
Modern Soil Mechanics (1910-1927)
Wolmar Fellenius (1876-1957)
Engineer from Sweden, developed the
stability analysis of saturated clay slopes (that is φ = 0 condition).
Modern Soil Mechanics (1910-1927)
Karl Terzaghi (1883-1963)
of Austria developed the
theory of consolidation for clays as we know today and was
published in Terzaghi’s celebrated book Erdbaumechanik
auf Bodenphysikalisher Grundlage in 1925.
- Father of Modern Soil Mechanics
- Presided the first conference of the International Society of
Soil Mechanics and Foundation Engineering (ISSMFE) held at
Harvard University in 1936. - In 1997, ISSMFE was changed to ISSMGE (International
Society of Soil Mechanics and Geotechnical Engineering)
Modern Soil Mechanics (1910-1927)
Ralph B. Peck (1912-2008)
Godfather of soil mechanics.
Rock Cycle and the Origin of Soil
Rocks can be divided into three basic types:
- Igneous rock
- Sedimentary rock
- Metamorphic rock
Igneous rock
are formed by solidification of molten magma
ejected from deep within the earth’s mantle.
Weathering
is the process of breaking down
rocks by mechanical and chemical processes
into smaller pieces.
Mechanical weathering
may be caused by the
expansion and contraction of rocks from the
continuous gain and loss of heat, which results
in ultimate disintegration.
chemical weathering
the original rock
minerals are transformed into new minerals
by chemical reaction. Water and carbon dioxide from the atmosphere form carbonic
acid, which reacts with the existing rock
minerals to form new minerals and soluble
salts
Transportation of Weathering Products
Residual soils
formed by the weathered products at their place of
origin, its important characteristic is the gradation of particle size.
Transportation of Weathering Products
Transported Soils:
Glacial soils
Glacial soils – formed by transportation
and deposition of glaciers.
Transportation of Weathering Products
Transported Soils:
Alluvial soils
transported by running water and deposited
along streams
Transportation of Weathering Products
Transported Soils:
Lacustrine soils
formed by deposition in quiet lakes
Transportation of Weathering Products
Transported Soils:
Marine soils
formed by deposition in the seas
Transportation of Weathering Products
Transported Soils:
Aeolian soils
transported and deposited by wind
Transportation of Weathering Products
Transported Soils:
Colluvial soils
formed by movement of soil from its original
place by gravity, such as during landslides
Sedimentary Rocks
The deposits of gravel, sand, silt, and clay formed
by weathering may become compacted by
overburden pressure and cemented by agents like
iron oxide, calcite, dolomite and quartz. They fill
the spaces between the particles and form
sedimentary rock.
Metamorphic Rocks
- form when rocks
are subjected to high heat, high
pressure, hot mineral-rich fluids or, more commonly, some combination of
these factors. Conditions like these are found deep within the Earth or where tectonic plates meet.
-
Metamorphism
is the process of
changing the composition and texture of rocks (without melting) by heat and
pressure.
EXAMPLES OF SEDIMENTARY ROCKS
- Conglomerate
- Breccia
- Sandstone
- Shale
- Mudstone
EXAMPLES OF SEDIMENTARY ROCKS
- Conglomerate
- Breccia
- Sandstone
- Shale
- Mudstone
EXAMPLES OF METAMORPHIC ROCKS
- Qartzite
- Slate
- Marble
- Gneiss
- Schist
- Serpentinite
