GEOTECHNICAL Flashcards
Soil in geotechnical engineering
(Iatin: solium); topsoil which consist of large quantity or organic matter and is not suitable as a construction materials or as foundation for structures.
SOIL MECHANICS
The term _______ was coined by Dr. Karl Terzaghi in 1925 when his book “ERDBAUMECHANIC” on the subject was published in GERMANY.
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.
Soils engineering
is the application of the principles of soil mechanics to practical problems.
Geotechnical engineering
is the subdiscipline of civil engineering that involves natural materials found close to the surface of the earth.
Early Observations (Ancient Times)
Egyptians and Mesopotamians, made basic observations about soil properties for constructing buildings and irrigation systems. Ancient Chinese texts also contain references to soil properties and their effects on construction.
Coulomb’s Frictional Theory (18th Century)
HISTORY: Charles-Augustin de Coulomb, a French engineer, introduced the concept of soil friction and cohesion in the late 18th century. He formulated equations to describe the stability of soil slopes and retaining walls based on these concepts.
Terzaghi’s Work (20th Century)
HISTORY: Karl Terzaghi; His work in the early 20th century laid the foundation for modern soil mechanics. Terzaghi developed fundamental principles for analyzing soil behavior under different loads and conditions. He introduced concepts such as effective stress and pore water pressure.
Consolidation Theory (1930s)
HISTORY: Terzaghi and Arthur Casagrande furthered the understanding of soil consolidation, which is essential for predicting settlement in foundations. Casagrande developed the widely used liquid limit and plastic limit tests for soil classification.
Ancient Civilization
HISTORY: Coulomb’s Frictional Theory (18th Century); Karl Terzaghi
Development of Laboratory Testing (20th Century)
HISTORY: significant advancements in soil testing techniques, including the introduction of the triaxial test and the direct shear test. These tests helped engineers better understand soil behavior under various loading conditions.
Father of Modern Geotechnology and Father of Soil Mechanics
Karl Terzaghi
Introduction of Geotechnical Engineering (Mid-20th Century)
HISTORY: Soil mechanics evolved into the broader field of geotechnical engineering, which encompasses soil behavior, rock mechanics, and foundation design. This expansion was driven by the need to address complex geotechnical challenges in construction projects.
Advances in Computational Methods (Late 20th Century)
HISTORY: With the advent of computers, numerical methods and finite element analysis became crucial tools for analyzing soil structure interactions and geotechnical problems.
Ongoing Research and Innovations (Present)
HISTORY: Soil mechanics continues to evolve with ongoing research into soil behavior, new testing methods, and innovative geotechnical engineering solutions. Today, soil mechanics plays a critical role in infrastructure development, including the design of buildings, bridges, dams, tunnels, and other civil engineering projects. It remains a dynamic field with a rich history of contributions from engineers and scientists worldwide.
Soil
is a complex mixture of mineral particles, organic matter, water, and air, along with living organisms. It forms because of the weathering of parent material (such as rocks and minerals) over time.
Mineral Particles
these are the solid, inorganic components of soil that originate from the breakdown of rocks and minerals through physical and chemical weathering processes.
The mineral particles are classified based on their size: SAND
The largest soil particle size, with diameters ranging from 0.05 to 2.0 millimeters.
The mineral particles are classified based on their size: SILT
Smaller than sand particles, with diameters ranging from 0.002 to 0.05 millimeters.
Weathering
is the process by which rocks and minerals are broken down into smaller particles and transformed through various physical, chemical, and biological mechanisms.
The mineral particles are classified based on their size: CLAY
The smallest soil particles, with diameters less than 0.002 millimeters.
Two main types of weathering
mechanical (physical) weathering and chemical weathering.
Mechanical (physical) weathering
involves the physical breakdown of rocks into smaller fragments without changing their chemical composition.
Chemical Weathering
involves the alteration of the chemical composition of rocks and minerals through reactions with water, gases, and other substances.
Biological Weathering
involves the actions of living organisms that contribute to the breakdown of rocks.
Types of rocks
igneous, sedimentary, metamorphic rock
Igneous rock
the solidification of molten magma ejected from deep within the earth’s mantle.
Sedimentary rock
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.
called Plutons
intrusive igneous rocks
Sometimes magma ceases its mobility below the earth’s surface and cools to form intrusive igneous rocks that are called ________.
Metamorphic rock
is the process of changing the composition and texture of rocks (without melting) by heat and pressure.
During metamorphism, new minerals are formed, and mineral grains are sheared to give a foliated texture to metamorphic rock
Cohesionless
Soil Particles do not stick together
Three Common Types: Gravel, Sand, and Silt
Cohesive
very small particle size where surface chemical effects predominate. The particles stick together. Both sticky and plastic.
Organic
Typically spongy, crumbly, and compressible, not ideal for supporting structures
Gravels
are pieces of rocks with occasional particles of quartz, feldspar, and other minerals.
Sand
particles are made of mostly quartz and feldspar
Silts
are the microscopic soil fractions that consist of very fine quartz grains and some flake-shaped particles that are fragments of micaceous minerals.
HYDROMETER ANALYSIS
for particle sizes smaller than 0.075 mm 2 in diameter.
Clays
are mostly flake-shaped microscopic and submicroscopic particles of mica, clay minerals, and other minerals.
SIEVE ANALYSIS
for particle sizes larger than 0.075 mm 1 in diameter
Sieve analysis
is a laboratory technique used to determine the particle size distribution of a granular material, such as soil, sand, gravel, and crushed stone. After the 6.3-mm size designation, a number designation is used, i.e., No. 4 to No. 400.
Hydrometer Analysis
is based on the principle of sedimentation of soil grains in water. When a soil specimen is dispersed in water, the particles settle at different velocities, depending on their shape, size, weight, and the viscosity of the water.
Cu
formula: Cu= D60/D10
Uniformity coefficient
Cc
formula: Cc= (D30)^2/D60*D10
Coefficient of gradation
formula: So= sq.rt. D75/D25
Sorting coefficient
poorly graded soil
most of the soil grains are the same size (CURVE 1)
well graded
the particle sizes are distributed over a wide range. A flat S-curve represents a soil which contains the particles of different sizes in good proportion. (CURVE 2)
gap graded
soil might have a combination of two or more uniformly graded fractions. A curve with a hump in which some of the intermediate size particles are missing. (CURVE 3)
particle shapes three major categories
bulky, flaky, and needle shaped
Bulky Particles
are formed mostly by mechanical weathering of rock and minerals. Geologists use such terms as angular, subangular, subrounded, and rounded to describe the shapes of bulky particles
Flaky Particles
have very low sphericity—usually 0.01 or less. These particles are predominantly clay minerals.
Needle-shaped Particles
are much less common than the other two particle types. Examples of soils are some coral deposits and attapulgite clays
Atterberg
developed a method to describe the consistency of fined-grained soils with varying moisture content
Behavior of Soils in four basic states
solid, semisolid, plastic, and liq
