Lesson 1: Soil Formation

Question 1

the uncemented aggregate of mineral grains and decayed organic matter (solid particles) with liquid and gas in the empty spaces between the solid particles

Answer 1

soil

Question 2

used as a construction material in various civil engineering projects and it supports structural foundations

Answer 2

soil

Question 3

what are the properties of soil?

Answer 3

• origin
• grain-size distribution
• ability to drain water
• compressibility
• shear strength
• load-bearing capacity

Question 4

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

Answer 4

soil mechanics

Question 5

subdiscipline of civil engineering that involves natural
materials found close to the surface of the earth; it includes the application of the principles of soil mechanics and rock mechanics to the design of foundations, retaining structures, and earth materials

Answer 5

geotechnical engineering

Question 6

what are the application of principles of soil mechanics to
engineering problem?

Answer 6

• highway retaining wall
• building basement walls
• bridge abutments
• earth dam
• waterfront bulkhead

Question 7

what are the examples of geotechnical systems?

Answer 7

• dams
• tunnels
• excavations
• slope stabilization
• earth retaining structures
• subgrade support
• ground improvements
• foundation for buildings

Question 8

give 2 examples of geotechnical failures

Answer 8

• leaning Tower of Pisa
• failure of Transcona Grain Elevator

Question 9

chemical elements that constitute rocks

Answer 9

minerals

Question 10

the aggregation of minerals into a hard mass

Answer 10

rocks

Question 11

materials that are derived from the weathering of rocks

Answer 11

soils

Question 12

average particle diameter of the soil at the 10th percentile or 10% of the particles are smaller that this diameter size

Answer 12

effective particle size (D-subscript-10)

Question 13

average particle diameter of the soil

Answer 13

average particle diameter (D-subscript-50)

Question 14

numerical measure of uniformity

Answer 14

uniformity of coefficient (C-subscript-u)

Question 15

measure of the shape of the particle distribution curve (coefficient of gradation/ coefficient of concavity)

Answer 15

coefficient of curvature (C-subscript-c)

Question 16

weathering of rock

Answer 16

soil

Question 17

process of which rocks are broken into pieces by physical force (e.g. water, wind, waves or ice and frost)

Answer 17

mechanical weathering

Question 18

process of chemical decomposition of the original rock

Answer 18

chemical weathering

Question 19

what are the 3 basic types of rocks?

Answer 19

• igneous rock
• sedimentary rock
• metamorphic rock

Question 20

soils that are formed by the weathered products at their place of origin; these soils retain many of the elements that comprise the parent rock

Answer 20

residual soil

Question 21

the composition of these soils depends on the environment under which they were transported and is often different from the parent rock

Answer 21

transported soil

Question 22

categories of transported soil:

soils from landslides or mudflows

Answer 22

colluvial or gravity transported

Question 23

categories of transported soil:

formed by deposition in quiet lakes

Answer 23

lacustrine

Question 24

categories of transported soil:

transported by running water & deposited along streams

Answer 24

alluvial

Question 25

categories of transported soil: formed by transportation and deposition from glaciers

Answer 25

glacial

Question 26

categories of transported soil: transported & deposited by wind

Answer 26

aeolian

Question 27

categories of transported soil: formed by deposition in the seas

Answer 27

marine

Question 28

crystalline materials and make up the solids constituent of a soil

Answer 28

minerals

Question 29

what are the two classifications of minerals?

Answer 29

*chemical composition *structure

Question 30

most minerals of interest to geotechnical engineers are composed of _____ and _____, two of the most abundant elements on earth

Answer 30

* oxygen * silicon

Question 31

the principal mineral of coarse- grained soils; it is hard and composed of silicon dioxide (SiO2) in colored, colorless, and transparent hexagonal crystals

Answer 31

quartz

Question 32

the particles of coarse-grained soil are naturally _____

Answer 32

angular

Question 33

complex aluminum silicates made of two distinct structural units

Answer 33

clay minerals

Question 34

composed of silica sheet

Answer 34

silicon tetrahedron

Question 35

composed of octahedral sheet/ gibbsite (Al) sheet or brucite (Mg) sheet

Answer 35

alumina octahedron

Question 36

what are the three clay minerals?

Answer 36

* kaolinite * illite * montmorillonite

Question 37

clay mineral that consists of repeating layers of elemental silica gibbsite sheets in 1:1 lattice; the layers are held together by hydrogen bonding and occurs as platelets

Answer 37

kaolinite

Question 38

clay mineral that is commonly used in paints, paper and in pottery and pharmaceutical industries

Answer 38

kaolinite

Question 39

(OH)8Al4Si4O10

Answer 39

kaolinite

Question 40

kaolinite family that has hydrated and tubular structure; (OH)8Al4Si4O10 * 4H2O

Answer 40

halloysite

Question 41

clay mineral that consists of gibbsite sheets bonded to two silica sheets - one at the top and another at the bottom, also bonded by potassium ions

Answer 41

illite

Question 42

illite sometimes called _____

Answer 42

clay mica

Question 43

clay mineral that has a structure similar to that of illite - one gibbsite sheet sandwiched between two silica sheets; there is isomorphous substitution of magnesium and iron for aluminum in the octahedral sheets; potassium ions are not present as in illite and large amount of water attracted into the space between the layers

Answer 43

montmorillonite

Question 44

clay mineral that expands on contact with water and highly reactive clay

Answer 44

montmorillonite

Question 45

montmorillonite is also called _____

Answer 45

smectite

Question 46

(OH)4Al4Si8O20 * nH2O

Answer 46

montmorillonite

Question 47

part montmorillonite family that is used as drilling mud, in slurry trench walls, stopping leaks

Answer 47

bentonite

Question 48

during deposition, the mineral particles are arranged into structural frameworks that we call _____

Answer 48

soil fabric

Question 49

common type of soil fabric where particles tend to orient parallel to one another

Answer 49

flocculated structure (saltwater environment)

Question 50

common types of soil fabric where particles oriented in perpendicular manner

Answer 50

flocculated structure (freshwater environment)

Question 51

common type of soil fabric that occurs when majority of the particles orient parallel to one another

Answer 51

dispersed structure

Question 52

what are the three major categories of particle shape?

Answer 52

* bulky particles * flaky particles * needle-shaped particles

Question 53

a particle shape that is mostly formed by mechanical weathering of rock and minerals

Answer 53

bulky particles

Question 54

described as angular, sub-angular, rounded, and sub-rounded

Answer 54

bulky particles

Question 55

a particle shape with very low sphericity, predominantly clay minerals

Answer 55

flaky particles

Question 56

a particle shape that is less common than the two other particle types; examples are some coral deposits and attapulgite clays

Answer 56

needle-shaped particles

Question 57

what are the three types of soil according to its particle size?

Answer 57

* gravel * sand * silt and clay

Question 58

soil type: pieces of rocks with occasional particles of quartz, feldspar, and other minerals

Answer 58

gravel

Question 59

soil type: mostly made of quartz and feldspar

Answer 59

sand

Question 60

soil type: consists of very fine quartz grain, mostly flake-shape microscopic and submicroscopic particles of mica, clay mineral and others

Answer 60

silt and clay

Question 61

what are the coarse-grained soil?

Answer 61

* gravel (G) * sand (S)

Question 62

a coarse-grained soil described as rounded and/or angular bulky hard rock, coarsely divided

Answer 62

gravel (G)

Question 63

a coarse-grained soil described as rounded and/or angular bulky hard rock, finely divided

Answer 63

sand (S)

Question 64

grain size of gravel: >75 mm

Answer 64

coarse

Question 65

grain size of gravel: 4.75 mm-19 mm

Answer 65

fine

Question 66

grain size of sand: 2.0 mm-4.75mm

Answer 66

coarse

Question 67

grain size of sand: 0.425 mm-2.0 mm)

Answer 67

medium

Question 68

grain size of sand: 0.075 mm-0.425 mm

Answer 68

fine

Question 69

what are the fine-grained soil (also called fines)?

Answer 69

* silt (M) * clay (C)

Question 70

a fine-grained soil described the particle size between clay and sand; nonplastic or very slightly plastic, exhibits little or no strength when dried; easily brushed off when dried

Answer 70

silt (M)

Question 71

a fine-grained soil described the particles as smooth and mostly clay minerals; greasy and sticky when wet; exhibits plasticity and significant strength when dried; water reduces strength

Answer 71

clay (C)

Question 72

what is the grain size of silt (M)?

Answer 72

0.002 mm-0.075 mm

Question 73

what is the grain size of clay (C)?

Answer 73

<0.002 mm

Question 74

determination of size range of particles present in a soil, expressed as % of the total dry weight

Answer 74

mechanical analysis of soil

Question 75

mechanical analysis method for particle sizes larger than 0.075 mm in diameter

Answer 75

sieve analysis

Question 76

mechanical analysis method for particle sizes smaller than 0.075 mm in diameter

Answer 76

hydrometer analysis

Question 77

a method that consists of shaking the soil sample through a set of sieves that have progressively smaller openings

Answer 77

sieve analysis

Question 78

a method based on the principle of sedimentation of soil grains in water

Answer 78

hydrometer analysis

Question 79

sieve number for 4.75 mm

Answer 79

4

Question 80

sieve number for 2 mm

Answer 80

10

Question 81

sieve number for 0.84 mm

Answer 81

20

Question 82

sieve number for 0.425 mm

Answer 82

40

Question 83

sieve number for 0.25 mm

Answer 83

60

Question 84

sieve number for 0.106 mm

Answer 84

140

Question 85

what are the parameters for particle size distribution curve?

Answer 85

* effective size (D-subscript-10) * uniformity coefficient (C-subscript-u) * coefficient of gradation (C-subscript-C) * sorting coefficient (S-subscript-0)

Question 86

a parameter for particle size distribution curve where the diameter in the particle-size distribution curve corresponding to 10% finer; good measure to estimate the hydraulic conductivity and drainage through soils

Answer 86

effective size (D-subscript-10)

Question 87

a parameter for particle size distribution curve defined as (C-subscript-60) over (C-subscript-10)

Answer 87

uniformity coefficient (C-subscript-u)

Question 88

a parameter for particle size distribution curve defined as (C-subscript-30) squared over (C-subscript-60) x (C-subscript-10)

Answer 88

coefficient of gradation (C-subscript-C)

Question 89

a parameter for particle size distribution curve defined as another measure of uniformity and is generally encountered in geologic works, expressed as: the square root of (D-subscript-75) over (D-subscript-25)

Answer 89

sorting coefficient (S-subscript-0)

Question 90

what are the different types of particle-size distribution curve?

Answer 90

* curve I (poorly graded) * curve II (well graded) * curve III (gap graded)

Question 91

a type of particle-size distribution curve that represents a type of soil in which most of the soil grains are the same size

Answer 91

curve I (poorly graded)

Question 92

a type of particle-size distribution curve that represents a soil in which particle sizes are distributed over a wide range

Answer 92

curve II (well graded)

Question 93

uniformity coefficient (Cu) for gravel

Answer 93

>4

Question 94

uniformity coefficient (Cu) for sand

Answer 94

>6

Question 95

uniformity coefficient (Cu) for sand and gravel

Answer 95

between 1 and 3

Question 96

a type of particle-size distribution curve where soil might have a combination of two or more uniformly graded fractions

Answer 96

curve III (gap graded)