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147 Cards in this Set

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Soil (engineering definition)
"Any unconsolidated material, regardless of origin Any material that can be excavated with a shovel.

Soils classified based on:
1) Particle Size 2) Particle size distribution 3) Plasticity of Material

Term 'regolith' also used

Examples: Actual Soil, Weathered residual material, Large clasts on a talus slope, glacial deposits, a beach
Soil (geological definition)
'the scum that covers the good stuff'
Soil Horizons
"distinct layers within the soil profile that form as a result of chemical weathering processes in addition to physical and biological processes

Descriptions of the soil profile are done by recognizing master horizons"
Master Horizons
"set of horizons found worldwide in lots of different places

Not all master horizons will form in a soil profile
Factors that impact formation of master horizons:
Physical conditions, chemical environment, biological activity, climate (Temperature and Precipitation), parent material and TIME

Master Horizons to Know:
O-->surface accumulation of mostly organic matter
A-->mixed mineral material and partly
decomposed organic material (humus)
E-->usually underlies O and A, less organic
matter, zone of eluviation (or leaching) of
metal oxides and clays
B-->underlies O, A and E, substances leached
from E accumulate in B (illuvial zone)
(several subdivisions within B horizon
based on substance that accumulates)
K-->very strongly impregnated CaCO3 layer
Carbonate makes up 50% or more by volume
C-->horizon containing parent material from which
the soil formed (parent material that has
undergone some weathering
R-->consolidated bedrock underlying the soil"
Cohesionless Soils
"coarse-grained soils with little clay content
No interparticle bonding, friction (ALONE)
determines shear strength
Important Index Properties:
1)Particle-size distribution, 2) Shape of particles, 3) Clay
content, 4) In-place density and relative density"
Cohesive Soils
"fine-grained soils that contain high amounts of silt and clay
both interparticle bonding and friction contribute to
overall shear strength
Important Index Properties:
1)Consistency, 2) Water content, 3) Atterberg limits, 4) Type and amount of clay, 5) Sensitivity"
containing a variety of particle sizes (similar to poorly sorted)
containing a narrow range of particle sizes (similar to well sorted)
"index property of cohesive soils
(def) strength and resistance to penetration of the soil in its in-place condition
(i.e.: resistance to jabbing a pencil into the soil)

Determined by:
Fabric-->arrangement of soil particles, particularly clays
Flocculated-->lots of edge to edge, non-ordered
contact of clay particles
Dispersed-->parallel arrangement of clay particles
Flocculated-->much stronger than dispersed
Remolding-->process of going from flocculated to
"index property of cohesive soils

ratio of the unconfined compressive strength in the undisturbed state to strength in the remolded state

St = (strength in undisturbed condition)/(strength in remolded
High sensitivity = highly unstable and dangerous"
Flocculated Soils
"arrangement of soil particles in clay soils
lots of edge to edge, non-ordered contact of clay particles

randomly, loosely oriented, not compacted
Flocculated orientation much stronger than
Dispersed Soils
"parallel arrangement of clay particles (compacted)

Weaker than flocculated arrangement
Remolding = process of going from flocculated to dispersed"
Atterberg Limits
"Water content values at which a soil changes physical state
Liquid Limit: water content level at which soil passes
from a liquid to a plastic state
Plastic Limit: decreasing water content limit at which the
soil passes into a semisolid state
Shrinkage Limit: continued decreasing water content, limit
at which the soil becomes a solid and
no longer shrinks in volume with
decreasing water contact
(at SL, all soil particles are in contact with one another)"
Angle of Internal Friction
"Measure of the shear strength of cohesionless soils
Successive direct shear tests with increasing normal
stress are conducted on a sample of cohesionless soil

For Cohesionless soils: plot of shear stress vs. normal stress from these tests results in a straight line

The angle of inclination of the line with respect to the horizontal axis is the angle of internal friction.

Angle of internal friction is determined by the material
(common values on slide 3 of Lecture 18 (03/21))

Stress plots for cohesive soils will also be linear, but they don't pass through the origin (angle of internal friction still defined with respect to horizontal)"
"vertical subsidence of a building foundation as soil compresses under load

Uneven settlement is a potentially serious problem"
"tendency for the soil to decrease in volume under load

can be measured by consolidation test
soil sample placed under a compressive load and void
space measured at various loads
Compression Index--slope of plot of decrease in void
space vs. normal pressure
(CI is used to predict amount of settlement)"
"process of soil compression

Rate of consolidation varies with soil properties

VERY SLOW in SATURATED CLAY-rich soils due to
very low permeability and high water content (drain
slowly---process can take a few years)

Total decrease in void ratio can be quite high in clay rich
soils, although it may take many years for equilibrium to
be reached (i.e.: lots of void spaces in flocculated
clays...once all the water gets out, the soil is
compacted a lot)"
"Soil Hazard common in arid regions

particles held in a loose arrangement by the presence of weak clay, water or precipitant bonds in an UNsaturated state

If the soil becomes water saturated, then these bonds are broken and the soil collapses on itself

Results in foundation settlement, utility line rupture, etc."
"Soil Hazard that results from conversion of a saturated soil to a liquid state under a rapid or cyclic stress

Commonly occur during earthquakes

Increased stress upon the soil from earthquakes can be great enough to suspend the soil particles in the pore water rather than driving the pore water from the soil

(load applied so rapidly water doesn't have time to escape

Results in total loss of shear strength and liquid behavior of the soil

Once the stress is removed, soil rapidly regains its strength"
"roughly circular pits resulting from surface collapse of soils into subsurface cavities

Regions commonly affected by surface collapse are:
Coal mining regions (i.e.: Pennsylvania)
Karst limestone regions
(Groundwater passing through limestone dissolves the
limestone resulting in subsurface voids)

Examples: Winter Park Sinkhole; Lake Jackson, FL
Mineralogical, chemical and structural adjustments of solid rocks in response to physical and chemical conditions different from the conditions under which the rocks originated
Contact Metamorphism
"alteration of the country rock by intruding magma
(Note: country rock is whatever the pre-existing rock was)

Characterized by High Temperature/Low Pressure
(Occurs deep in the earth, there is some pressure but
relatively low with respect to other types of metamorphism)"
Burial Metamorphism
"alteration of rocks due to the increase in pressure and temperature associated with increasing depth in the Earth's crust

Characterized by Moderate Temperature and Pressure
(Caused by accumulation of sediments on top of the rocks as in the formation of sedimentary basins)"
Regional Metamorphism
"alteration of a region of rocks in response to tectonic compression
(i.e.: at convergent plate margins/formation of mountain belts)

Moderate to High Temperature and Pressure"
Dynamic Metamorphism
"alteration of rock due to extremely high pressures

Low Temperature/High Pressure (Fault Zones)"
Country Rock
whatever the pre-existing rock was that's being metamorphosed
"the original rock before metamorphism (same as country rock?)
""Metamorphic processes result in a change in the protolith""

Protolith composition plays a major role in determining composition of the resulting metamorphic rock

In a CLOSED system, new mineral creation by metamorphic processes is limited by composition of protolith

OPEN system--metamorphic process can introduce new minerals"
"One of 2 main metamorphic textures

A metamorphic rock is foliated if it has a parallel orientation of grains within the rock

Usually has a banded or layered look that superficially resembles sedimentary rock

Engineering Properties similar to sedimentary rocks (susceptible to failure along foliation planes)

2 Common Cases:
1) Foliation is a relic of sedimentary bedding (i.e.: protolith was a sedimentary rock)
2) Protolith may have no bedding, but metamorphic rock has strong foliation due to directed stress
Common in regional metamorphic terrains
Tectonic forces applied in one direction
Growth of new minerals (micas) with long axis
perp. to directed stress
Where high temps. are present, shearing of
existing minerals, elongated parallel to applied force
"One of 2 main metamorphic textures

Occurs when there is little or no directed stress

Common in contact and burial metamorphism where there is no preferred direction of growth (constant pressure from all sides)

Engineering properties similar to igneous rocks (strong, no planes of weakness)"
"Non-foliated metamorphic rock that forms from a limestone protolith

Re-crystallization process results in interlocking grains of calcite or dolomite

Example of a rock that forms from thermal metamorphism (i.e.: in response to high temperatures)"
"Non-foliated metamorphic rock that forms from a sandstone protolith
High Temps of metamorphism homogenize crystal structure, get rid of void spaces
One of the hardest rock's on the Earth's surface"
"well-foliated metamorphic rocks with coarser grains and higher metamorphic grade than slate
(often have visible alignment of micas)
Many types of igneous and sedimentary rocks can be metamorphosed to form schist

Metamorphic grade refers to degree of metamorphism
High grade is high degree of metamorphism
Low grade is low degree of metamorphism

Schist is 'mid-grade' metamorphism (more than slate less than gneiss)
"well-foliated rock that develops under high-grade metamorphic conditions

Coarse-grained, coarse banded rock that consists of alternate bands of light and dark-colored minerals

Form from silicic igneous and various types of sedimentary rocks"
"well-foliated rock produced by low-grade metamorphism of shale (usually directed pressures and low temps)

Foliation planes are planes of weakness"
"rate at which fluids will move through a saturated material
Determined by size and connectedness of the voids AND
the properties of the fluid (temperature, viscosity, density)"
"Intrinsic Permeability (k)
(units: cm^2 or darcys)"
"permeability defined by the properties of the material
Depends on:
size, shape, packing of the grains
degree of cementation
degree of fracturing"
"Hydraulic Conductivity (K)
(units: m/s)"
"measure of the ability of a rock or soil to transmit water
Equation: K= k*(ρg/µ)
k = intrinsic permeability
ρ = density of water
µ = viscosity of water
g = acceleration due to gravity
Hydraulic conductivity combines k with the properties of the fluid...can change dramatically if fluid properties change (i.e.: hydrocarbon contamination)"
"Type of ideal deformation response characterized by:
Linear plot of stress vs. strain
Slope is the modulus of elasticity (E)
E = σ/ε
Strain (ε) is the change in length vs the original length
Strain in elastic systems is recoverable"
Unsaturated Zone
partial filling of void spaces by water (aka vadose zone)
Saturated Zone
complete filling of void spaces with water
Phreatic Zone
below the water table
Capillary Zone
above the water table
Water Table
point at which the fluid pressure is equal to atmospheric pressure
Equipotential lines
(black lines) lines that connect points of equal head (i.e. there is
no hydraulic gradient along an equipotentail line)
Flow lines
(curved lines with arrows) water will always flow from greatest head
to lowest head in a direction perpendicular to equipotential lines
addition of water to the groundwater system through rainfall or
removal of water from the groundwater system
saturated body of rock or soil that transmits economically significant quantities of
unit of rock that does not transmit groundwater at economically
feasible rates (Impermeable layers, dense non-fractured rock units)
unit of rock that does not transmit groundwater (uncommon to
absent in nature--all rocks tend to transmit some water)
Unconfined aquifers
lack an overlying aquitard or aquiclude; water table is upper
Confined aquifer
bounded above and below by aquitards or aquicludes
Potentiometric surface
contours defined by the hydraulic head in wells of confined aquifers define potent surf;
if rises above land surface, artesian wells occur
Perched aquifer
form when lenses of impermeable material form smallish localized
aquitards in the unsaturated zone; small aquifers can develop above
these lenses; usually have low yields
Residence time
amount of time water spends in an aquifer (important bc length of
time it takes contaminants into deep confined aquifers)
Cone of depression
when water is pumped from an unconfined aquifer, this is formed
balance of discharge and recharge; discharge=recharge ->
equilibrium; discharge < recharge -> also in good shape; discharge
> recharge -> TROUBLE
limestone and dolomite are readily soluble by groundwater; over
time surface flow will transfer from surface runoff and drainage to
subsurface drainage with hardly any surface runoff; over time
surface will develop into a sinkhole plain
Diffuse flow
initial stages of Karst development; flow follows minute cracks and
joints in the rock, similar to usual groundwater movement
Mixed flow
second stage of Karts development; the minute cracks and joints
enlarge due to solution of the limestone and these become
preferential conduits but still some aspects of diffuse flow
Secured Landfill
used for disposal of hazardous wastes; requires engineered
leachate barriers; regular monitoring of unsaturated/saturated zones
Sanitary Landfill
used for disposal of less hazardous wastes; modern design tends
to try to isolate the waste into "cells" within the overall landfill
Acid mine drainage
sulfide minerals oxidize to produce sulfuric acid; very low pH, helps
mobilize metals
Injection wells
first used to dispose of brines brought up with oil; now used by
chemical industry to dispose of hazardous chemicals; commonly
very deep (hundreds of thousands of meters); typically try to inject
waste into permeable layer that doesn't contain useable
groundwater that is overlain by one or more aquitards
Aqueous-phase liquids
contaminant is dissolved in water
Nonaqueous-phase liquids (NAPLs)
contaminant is non-immiscible in water
dense non-aqueous phase liquid; denser than water
light non-aquesous phase liquid; less dense than water (includes
the petroleum products)
Pendular Zone
fluid pressure << atmospheric pressure and pores only slightly
saturated, air dominates pore space, no more reducation in
saturation level; matric potential << 0, results in thin films and
narrow capillaries filled with water
Funicular Zone
fluid pressure < atmospheric pressure and pores are only partially
saturated, but water dominates pore space; matric potential << 0
transport by the bulk movement of flowing water in response to the
hydraulic gradient; rate of movement = average linear velocity; why
average? Lots of different paths that the flow can take, each will
have a different velocity; v = KI/n where K = hydraulic conductivity,
I = hydraulic gradient, n = porosity
Hydrodynamic dispersion
results in spreading of the contaminated zone along the flow path;
higher flow rates in the center of the plume that the margins; more
rapid flow through the larger pores; lateral expansion of the
contaminant due to having a flow around aquifer grains; results in
the fixed mass of contaminants being spread over larger area =
reduction in concentration
Oil layer
Gasoline = LNAPL; begins to pool at the top of the capillary fringe
in a layer termed the "free product"; will migrate along the top of the
capillary fringe in the direction of the slope in the water table; top
of the free product forms the "oil layer"
a type of ideal material; in a linear plot of stress vs. strain viscosity is the slope; it is non-recoverable
a type of ideal material; no strain until some critical stress value has been reached and then continuous deformation after that
respond in a mostly elastic fashion until failure (breakage of the rock, usually results in earthquakes)
respond in a mostly plastic fashion until failure (folding of the rock)
Rock Mass Rating System
system to quantify many factors to determine the quality of a rock mass (Table 7.8-7.10)
Strike & Dip
method to measure the orientation of planar elements within a rock body
direction of the line formed by intersection of the plane and the horizontal (measured in degrees from north)
amount of slope on the plane, always measured on a vertical plane perpendicular to strike, measured in degrees from horizontal
a type of fold - upward bending, shaped like an arch
a type of fold - downward bending, shaped like a U
a type of fold - limbs dip in opposite directions at the same angle
a type of fold - limbs dip in opposite directions in different angles
limbs dip in same direction
recumbent folds
axial plane nearly horizontal
axial plane
a plane containing the axis that divides the fold into two equal sections
evidence of a brittle deformation (difference btwn joint/fault - joints have no had movement occur along the failure plane); produced by cooling of igneous rocks, unloading durin erosion, compressional tensile and shearing stresses (these tend to form in sets of parallel planes throughout the rock body); are planes of weakness and the overall stability of the rock body will be controlled by the orientation and spacing of the join
fractures that movement has occurred along; classified by the type of movement (slip) that has occurred
movement has occurred in the direction of the dip of the fault plane
movement has occurred in the direction of the strike of the fault plane (transform, strike-slip)
hanging wall
the "top wall" if a miner attached himself to one this wall he would "hang" from it
foot wall
the "bottom wall" if a miner attached himself to this wall, he could stand on it (without falling)
normal fault
hanging wall has moved down, extensional
reverse fault
hanging wall has moved up, compressional
thrust fault
low angle reverse fault, compressional
fault scarp
the exposed and eroded fault plane
paired dip-slip faults result in this; specifically - 2 reverse faults result in this
paired dip-slip faults result in this; specifically - 2 normal faults result in this
right and left lateral strike-slip faults
determine by facing the fault and noting in which direction the movement appears to have gone relative to you (right or left)
where the strain release actually occurs along the fault
point on the Earth's surface directly above the hypocenter; point where seismic waves first reach the surface, usually most severe ground motion
P wave
primary waves, compressional; travel trhough Earth's interior, travel the fasest of all waves
S wave
secondary (or shear) waves, shear; travel through Earth's interior, next fastest wave (after primary)
Rayleigh wave
a type of surface wave (long periods, slow, travel only on surface); like ocean waves, vertical displacement
Love wave
a type of surface wave (long periods, slow, travel only on surface); horizontal ground motion, result from S waves reaching surface at epicenter
instrument used to measure the intensity of the seismic waves
chart of the wave vibrations
Modified Mercalli Scale
measure of the intensity - subjective measurement based on damage and personal interviews (12 different divisions - see Table 16.2); the same earthquake results in different divisions depending upon the location of the person recording it
Fundamental Period
a natural vibration that both buildings and geological materials have (bedrock and stiff soils <1s, soft soils = several seconds, tall buildings = several seconds, short stiff buildings <1s); if the building and ground have similar fundamental periods - resonance occurs and more damage is the usual result ALSO tall building built on soft soilds tend to suffer the greatest damage due to similarities in fundamental period
a fundamental natural resource (used for drinking water, sanitation, irrigation/agriculture, livestock water, industry, recreation)
Free product layer
The pool of gasoline that forms at the top of the capillary fringe
sufficiently massive body of interlocking snow and ice crystals that flows downslope under its own weight
dense granular snow/ice resulting from compaction of snow, eventually compaction of the firn results in the total recrystallization and formation of glacial ice
Snow line
elevation above which snow more or less remains all year long
Zone of Accumulation
area of glacier that snowfall exceeds melting/sublimation
Zone of Ablation
area of glacier that melting/sublimation exceeds snowfall
Equilibrium Line
area where snow fall equals melting/sublimation
Basal sliding
tendency of the glacier to slide as a block above its bed
Cold-based glacier
moves only by visco-plastic deformation
Wet-based glacier
moves both by visco-plastic deformation and by basal sliding
Deforming Bed Hypothesis
When moving over a bed of weathered rock/weak sedimentary rock/old glacial sediments, the glacier may couple to the bed and deform it so that the bed material is moving at some velocity
large glacial cracks, in the brittle zone/upper part of the glacier
Brittle Zone
upper portion of the glacier
Visco-plastic Zone
portion of the glacier below brittle zone where crevasses do not form, ice deforms 'in a visco-plastic way'
Glacial striations
elongated grooves caused by abrasion of the bed by traveling rocks; form parallel to the direction of ice flow, only occurs in wet-based glaciers
process of incorporation of large block of bedrock into the glacier
Ice thrusting
ice freezes to bedrock and shearing of the bed results in large slabs being mobilized into the glacier, occurs in cold-based regions
Roche Moutonnes
a rock hill shaped by the passage of ice to give a smooth up-ice side and a rough, plucked and cliff-girt surface on the down-ice side
U-shaped valley
valley formed by erosions of glaciers; characteristic steep, straight sides, and a flat bottom, ice flows tend to form U-shaped valleys whereas streams and rivers form V-shaped valleys
point where aretes coalesce; sharply pointed pinnacle that forms when 2 or more glaciers erode headward at the base of a mountain peak
narrow ridge that separates two glaciated valleys and is often quite steep and sharp
a gap produced in a ridge by the headward erosion of glaciers in two cirques from opposite sides of the ridge
bowl-shaped depression at the base of a mountain peak where glaciers form and begin to flow downvalley
Hanging Valley
tributary glacial valley with the floor at higher relief than the valley into which it flows, most commonly associated with U-shaped valleys when a tributary glacier flows into a glacier of larger volume
catch-all term for any glacial deposits
nonsorted, nonstratified sediment deposited by glacial ice
Basal till
deposited at the base of wet-based glaciers, dense and compact
Ablation till
originates as debris from ice thrusting or plucking that is transported from the base to the glacier to the ablation area
Ice-contact stratified drift
debris deposited by meltwater moving around, through, or on top of glacier
ridge of drift
Lateral moraine
narrow ridge of drift that is deposited along the lateral edge of valley glaciers and of outlet glaciers against the valley wall
Medial moraine
longitudinal debris bands in the glacier in the main valley formed from lateral moraines from glaciers that formed in tributary valleys
End moraine (terminal moraine)
ridge of drift deposited by the glacier at its point of maximum advance
Ice sheet/ice cap
large expanses of ice with a dome-shaped profile
ice sheets are greater than 50,000 km^2 while caps less than 50,000 km^2
gravel, sand, and silt deposited in front of the glacier