(MODULE 9.2) ENGINEERING BEHAVIOR AND PROPERTIES OF SOIL AND ROCKS

Question 1

soils are derived from the ___

Answer 1

weathering of rocks

Question 2

soils are broadly described by terms such as ___, ___, ___, and ___

Answer 2

gravels, sands, silts, and clays

Question 3

physical weathering causes ___ of the parent rock without ___

Answer 3

reduction in size; change in its composition

Question 4

chemical weathering causes ___ and ___.

Answer 4

reduction in size of the parent rock and change in chemical composition

Question 5

gravels, sands, silts, and clays are used to identify specific textures in soils. these soil textures are referred to as ___

Answer 5

soil types

Question 6

sands and gravels are grouped together as ___

Answer 6

coarse-grained soils

Question 7

clays and silts are ___

Answer 7

fine-grained soils

Question 8

coarse-grained soils feel ___

Answer 8

gritty and hard

Question 9

the coarseness of soils is determined from knowing the ___, which is the primary means of classifying coarse-grained soils

Answer 9

distribution of particle sizes

Question 10

fine-grained soils feel ___

Answer 10

smooth

Question 11

to characterize fine-grained soils, we need ___

Answer 11

further information on the minerals present and their contents

Question 12

fine-grained soils have a ___ arrangement

Answer 12

flaky

Question 13

soil minerals

the principal mineral of coarse-grained soils

Answer 13

quartz

Question 14

the mineral particles of fine-grained soils are ___

Answer 14

platy

Question 15

the main groups of crystalline materials that make up fine-grained soils are the minerals ___, ___, and ___

Answer 15

kaolinite, illite, and montmorillonite

Question 16

minerals are ___ and make up the solid’s ___

Answer 16

crystalline materials; constituent of a soil

Question 17

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

Answer 17

soil fabric

Question 18

the environment under which deposition occurs influences the ___

Answer 18

structural framework that is formed

Question 19

in particular, the ___ has the greatest influence on the kind of soil fabric formed during deposition of fine-grained soils.

Answer 19

electrochemical environment

Question 20

two common types of soil fabric are formed during deposition of fine-grained soils:
1.
2.

Answer 20

1. flocculated
2. dispersed

Question 21

a flocculated structure, formed in a saltwater environment results in ___

Answer 21

many particles arranging parallel to one another

Question 22

a flocculated structure, formed in a freshwater environment, results in ___

Answer 22

many particles arranging perpendicular to one another

Question 23

this structure of soil fabric occurs when a majority of the particles orient parallel to one another.

Answer 23

dispersed structure

Question 24

the spaces between the mineral particles are called ___, which may be filled with
1.
2.
3.

Answer 24

voids; liquids, gases, and cement minerals

Question 25

coarse-grained soils have ___, ___, and ___

Answer 25

good load-bearing capacities, good drainage qualities, and strength

Question 26

course-grained soils are incompressible when dense, but ___ can occur when they are loose

Answer 26

significant volume changes

Question 27

___ accentuate volume changes in loose, coarse-grained soils by ___.

Answer 27

vibrations; rearranging the soil fabric into a dense configuration

Question 28

coarse-grained soils with ___ have ___, ___, and ___ than coarse-grained soils with rounded particles

Answer 28

angular coarse-grained soils; higher strengths, higher compressibility, lower densities

Question 29

why are angular particles of coarse-grained soils sturdier than rounded particles?

Answer 29

if you have angular particles, the contact between them would increase friction. the increase in friction would let it have higher strengths and compressibility. due to it being angular, it tends to have lesser voids than rounded particles.

Question 30

coarse-grained soils are generally described as ___

Answer 30

free draining

Question 31

free draining means that ___

Answer 31

the soil allows free passage of water in a relatively short time

Question 32

___ can significantly alter the flow conditions in these soils

Answer 32

fines content (silts and clays)

Question 33

gravel, boulders, and coarse sands with fins content less than ___ are ___

Answer 33

5%; free draining

Question 34

__, especially if it exists as a thick layer, is not free draining.

Answer 34

fine sand

Question 35

___ means it has high permeability, meaning there is a lot of seepage that can happen within the coarse-grained soils.

Answer 35

free draining

Question 36

fine-grained soils have ___ compared with coarse-grained soils.

Answer 36

poor load-bearing capacities

Question 37

fine-grained soils are practically ___, ___. and are ___.

Answer 37

impermeable, change in volume and strength, susceptible to frost

Question 38

___ control, the engineering properties of fine-grained soils, in contrast to course-grained soils whose properties depend on grain size and shape.

Answer 38

mineralogical factors

Question 39

___ have been responsible for many geotechnical failures.

Answer 39

thin layers of fine-grained soils, even within thick deposits of coarse-grained soils

Question 40

when there are no joints, ideally, the rock mass and the intact rock should have the same properties, provided the rock is ___

Answer 40

homogeneous

Question 41

joints within a joint set are approximately ___

Answer 41

parallel

Question 42

intact rock: ___

Answer 42

isotropic properties

Question 43

isotropic: ___

Answer 43

same properties in all directions

Question 44

a collective term used for all structural breaks (bedding planes, fractures, and joints) in solid geologic materials that usually have zero to low tensile strength

Answer 44

discontiniuity

Question 45

the discontinuities make the rock mass ___

Answer 45

anisotropic

Question 46

the amount of joint sets can be identified by ___

Answer 46

seeing the differing orientation of joints, linking a set to joints with the same angle.

Question 47

factors affecting discontinuities 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Answer 47

1. orientation 2. spacing 3. persistence 4. roughness 5. wall strength 6. aperture 7. filling 8. seepage 9. number of joint sets 10. block size and shape

Question 48

measured by the dip and dip direction of a discontinuity, very critical to stability; in the right direction, the stability of a rock can be affected significantly, positive or negative.

Answer 48

orientation

Question 49

if the discontinuity plane or fracture continues from the top of the slope to the bottom, the steep dip angle will ___

Answer 49

cause mass wasting because of the discontinuity plane lying like a bed underneath the mass above.

Question 50

the perpendicular distance between two adjacent discontinuities of the same set

Answer 50

spacing

Question 51

it affects the ___ of the rock mass and the ___.

Answer 51

hydraulic conductivity; failure mechanism

Question 52

closely spaced joints can imply ___

Answer 52

highly permeable rock

Question 53

if the spacing is too close to each other, ___, increasing permeability

Answer 53

water can find a path to flow through

Question 54

the measure of the extent to which the discontinuity extends to the rock

Answer 54

persistence

Question 55

what is the surface area of the discontinuity?

Answer 55

this is the area that takes part in any possible sliding, and hence is an important parameter in determining stability.

Question 56

refers to the large-scale surface undulations observed over several meters and the small-scale unevenness of the two sides relative to the mean plane, observed over several centimeters.

Answer 56

roughness

Question 57

roughness large-scale undulations can be called ___, ___, or ___.

Answer 57

stepped, undulating, or planar

Question 58

roughness small-scale unevenness can be called ___, ___, or ___.

Answer 58

rough, smooth, or slickensided

Question 59

roughness is measured using the ___ method.

Answer 59

linear profiling

Question 60

this tool provides useful basis for examining some of the issues associated with estimation of roughness.

Answer 60

profile gauge tool

Question 61

refers to the compressive strength of the rock that makes up the walls of the discontinuity

Answer 61

wall strength

Question 62

wall strength is an important factor that governs the ___ and ___

Answer 62

shear strength and deformability

Question 63

the perpendicular distance between the two adjacent rock walls of an open discontinuity where the space is filled by air or water.

Answer 63

aperture

Question 64

a joint is called either tight or open, depending on whether the ___

Answer 64

aperture is small or large

Question 65

the term used to describe the material that occupies the space between the adjacent rock walls of a discontinuity

Answer 65

filling

Question 66

filling affects the ___ and ___ of the rock mass

Answer 66

permeability and deformability

Question 67

the permeability of a given rock mass

Answer 67

seepage

Question 68

determines the ability of the rock mass to deform without undergoing failure

Answer 68

number of joint sets

Question 69

as the number of joint sets increases, the ___ decreases and their ___ increase

Answer 69

individual block size; degrees of freedom to move

Question 70

the rock mass consists of ___ formed by intersections of several joints

Answer 70

blocks