Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
111 Cards in this Set
- Front
- Back
I=
|
H/L
|
|
Overburden pressure =
|
unit weight of soil X depth
|
|
overburden pressure w/ water =
|
(total soil unit weight - unit weight of water) X depth
|
|
total soil unit weight =
|
125 pcf
|
|
unit weight of water =
|
62.4 pcf
|
|
at some point in time subjected to load greater than present overburden pressure
(normally consolidated clay or over consolidated clay) |
over consolidated clay
|
|
only subjected to overburden pressure equal to present overburden pressure
(normally consolidated clay or over consolidated clay) |
normally consolidated clay
|
|
these soils generally withstand greater loading with little or no settlement
(normally consolidated clay or over consolidated clay) |
over consolidated clay
|
|
3 common causes of consolidation of soil and settlement of structures
|
removal or overburden though erosion
melting of overriding glacial ice removal of an old structure |
|
most settlement on sand occurs by...
|
completion of construction
|
|
with settlement on sand, the ____ of settlement is not a factor as it is with clay
|
time
|
|
is the time of settlement a factor with clay
|
yes
|
|
settlement (clay) results from (3)
|
reduction in voids
rearrangement of soil grains compression of material in voids |
|
is primary or secondary consolidation usually the greatest
|
primary
|
|
extrusion of water from voids of a fine grained soil (primary or secondary consolidation)
|
primary
|
|
plastic readjustments of soil grains (primary or secondary consolidation)
|
secondary
|
|
q =
|
volume of water discharged
|
|
L =
|
length
|
|
a =
|
cross sectional area
|
|
h =
|
head
|
|
water flow permeameter is ________, on site flow is __________
|
downward
horizontal |
|
in situ is latin for
|
on site
|
|
smooth walls of permeameter vary from...
|
natural soils
|
|
field soils are
|
undisturbed
|
|
soil ____________ occurs in the field
|
satisfaction
|
|
field soil is often...
|
non-homogeneous
|
|
difference in lab tests vs on site tests is the location of the...
|
groundwater table
|
|
darcy's law applies for ____-_______ ____ over a long ________
|
well-defined flow
distance |
|
if flow is short or irregular, use
|
flow nets
|
|
a path a water particle follows is a
|
flow line
|
|
these connect points on different flow lines having equal total energy heads
|
equipotential lines
|
|
water rises up through voids from water table
|
capillary rise
|
|
is an accurate calculation of capillary rise easy?
|
no, virtually impossible
|
|
smaller grain size = _______ ____ _____
|
smaller void space
|
|
smaller void space =
|
greater capillary rise
|
|
____ has low capillary rise and low permeability
|
clay
|
|
what has the greatest capillary rise
|
fine grain sizes
|
|
examples of fine grain sizes
|
silts and very fine sands
|
|
vertical expansion of soil
|
frost heave
|
|
what is the best defense against frost heave
|
construct foundations deep enough to escape effects of frost heave
|
|
entire void space filled with water
|
saturated
|
|
voids partially filled with water
|
partially saturated
|
|
water content greatly effects the characteristics and engineering behavior especially for
|
fine grained soils
|
|
soil characteristics and engineering behavior are greatly influenced by
|
water content
|
|
cohesive soils (clay) are hard as a rock when
|
dry
|
|
cohesive soils (clay) are soft and plastic when
|
wet
|
|
cohesive soils (clay) shrink when
|
dry
|
|
cohesive soils (clay) swell when
|
wet
|
|
these are weakened at high water contents
|
fine grained soils
|
|
sandy soil is _____ when dry and rather ____ when wet
|
loose
hard |
|
greater permeability means there is
|
more void space
|
|
the water flow through soil
|
permeability
|
|
low voids means there is
|
low permeability
|
|
fine grained soils (clay) high or low permeability
|
low
|
|
coarse grained (sand) high or low permeability
|
high
|
|
pressure which causes water flow in soils
|
hydraulic head
|
|
darcy's law analyzes _____ ____ in soils
|
water flow
|
|
i =
|
hydraulic gradient
|
|
k =
|
coefficient of permeability
|
|
velocity of flow varies directly with
|
difference in hydraulic heads
|
|
coefficient of permeability (k) may be quarantined in terms of
|
grain size distribution
|
|
flow rate through soil varies inversely with
|
length in which hydraulic head occured
|
|
compaction increases _____ strength
|
shear
|
|
compaction increases
|
bearing capacity
|
|
compaction decreases
|
permeability
|
|
compaction reduces soil _________ and _____
|
shrinkage and swell
|
|
compaction increases resistance to
|
erosion
|
|
to press the soil particles tightly together by expelling air from the void space
|
compaction
|
|
compaction is normally produced deliberately and proceeds rapidly during
|
construction
|
|
results in the reduction of voids, but as a result of extrusion of water from the void space
|
consolidation
|
|
is consolidation rapid
|
no
|
|
compaction is defined by (2)
|
dry unit weight
moisture content |
|
for a given compactive effort, there is a particular
|
moisture content
|
|
you reach 100% compaction at (2)
|
maximum dry density
optimum moisture |
|
density =
|
weight/volume
|
|
MDD range for organic
|
60-80
|
|
MDD range for granular, well graded
|
120+ lb/ft cubed
|
|
optimum moisture for gravel
|
7%
|
|
optimum moisture for sand
|
10%
|
|
optimum moisture for heavy clay
|
17.5%
|
|
typical clay optimum moisture is
|
15-30%
|
|
typical sands/silts optimum moisture is
|
10-20%
|
|
typical density of concrete
|
200
|
|
field test for in place density (3)
|
troxler nuclear density device
sand cone rubber balloon |
|
lab test for MDD
|
5-point proctor
|
|
field tests for MDD (2)
|
MDOT T-99
MDOT 1-point cone test |
|
5-point proctor lab test at
|
5 moisture contents
|
|
# of blows per layer
|
25
|
|
# layers with 25 blows each
|
3
|
|
weight of hammer
|
5.5 lbs
|
|
volume of mold was
|
1/30 ft cubed
|
|
sub grades and embankments
base courses pavement smooth finished grades what type of roller |
smooth wheeled
|
|
clayey or silty soils
granular material - sandy soils what type of roller |
pneumatic roller
|
|
best for compacting cohesive soils
fine grained soils (sand w/ clays and silts) moderate effectiveness on silts and clays not effective in uniformly graded sand what type of roller |
sheepsfoot roller
|
|
can be combined with other roller types
granular material clean sands and gravels less effective in cohesive soils what type of roller |
vibratory roller
|
|
used in trenches and narrow spots
hand operated - vertical blows |
tamper
|
|
dynamic compaction:
weight from ______ height from ______ |
2-20 TONS
20-100 FEET |
|
typically obtain ___-___ % + of MDD
|
95-98
|
|
for soil stabilization, chemicals can be added like
|
lime
|
|
for soil stabilization, fabric material can be used like
|
geosynthetics (geotextile fabric)
|
|
used to densify (stabilize) existing soils when compactors will not be used on the soil
|
soil stabilization
|
|
few points of contact
poor interlock high permeability |
poorly graded
|
|
good interlock
low permeability |
well graded
|
|
only limited sizes
good interlock low permeability |
gap graded
|
|
3 types of grain size distribution
|
poorly graded, well graded, gap graded
|
|
what lubricates soil particles
|
water
|
|
what creates clay particle bonding
|
water
|
|
are clays of high plasticity good for compaction
|
yes
|
|
is uniformly graded sand good for compaction
|
yes
|
|
shape of grains
|
angular
rounded |
|
what is the typical optimum moisture of A1A
|
7-15%
|