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Existing Site Conditions & Earthwork
Soil Investigation methods:
Compacted Volume =
Existing Site Conditions & Earthwork
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1
Compacted Volume =
bank volume x shrinkage factor
bank density / compacted density
1 - shrinkage
( 1 - bank density / compacted density ) x 100
2
Soil Investigation methods:
excavate for samples
penetrate soil to a predetermined distance
drill holed with an auger and wash boring techniques
sample the top soil
3
Steps to building a slurry wall:
layout, excavation, interject the slurry, install reinforcement, place conc
excavation, layout, interject the slurry, place conc., install reinforc.
excavation, interject the slurry, install reinforcement, place concrete
layout, excavation, interject the slurry, place concrete, install reinforc.
4
The max angle of repose without the use of sheeting: (rise/run)
3/4
4/3
3/2
2/3
5
Cobble:
spherical particles, too small to see with unaided eye
particles too small to be indivually lifted between fingers
can be lifted with one hand
too big to lift with one hand
6
Gravel:
Particles too small to individually lifted between fingers
spherical particles, too small to see with the unaided eye
smaller than silt, plate-shaped
Individual particles can be lifted between thumb and forefinger
7
Site preparation can include:
remove and save existing soil
demolish and dispose of structures
remove trees and plants
remove parking areas
8
environmental assessment:
used to approve or deny a construction plan
reports on effects of construction on surroundings
required by National Environmental Policy Act
can't affect a construction plan
9
Swell (%) =
bank density / loose density
(bank dens./loose dens - 1) x 100
loose volume x load factor
loose density / bank density
10
Bank Material:
material in natural state
a unit volume is identified as compacted cubic yard (CCY)
a unit volume is identified as a bank cubic yard (BCY)
material after compaction
11
Sump Pumps:
most common and least expensive
water collected and pumped out
requires a clearance around excavations
pumps placed in low points
12
Density is equal to weight per volume, more dense = more compacted.
True
False
13
Clay:
smaller than silt, plate-shaped
Particles too small to individually lifted between fingers
spherical particles, too small to see with the unaided eye
Individual particles can be lifted between thumb and forefinger
14
Bank Volume =
(bank dens./loose dens - 1) x 100
loose density / bank density
loose volume x load factor
bank density / loose density
15
A soil increases in volume when it is compacted.
True
False
16
Silt:
Individual particles can be lifted between thumb and forefinger
spherical particles, too small to see with the unaided eye
smaller than silt, plate-shaped
Particles too small to individually lifted between fingers
17
Common excavation and backfill problems:
water table
rock / boulders / unsuitable material or soil
weather
site access
18
Grading:
removed rock and soil is stockpiled
removing earth
can be shallow or deep
adjusting of the ground
19
Load Factor =
loose density / bank density
(bank dens./loose dens - 1) x 100
loose volume x load factor
bank density / loose density
20
Professionals involved in site investigation and planning:
architects
owner
managers
engineers
21
Fine-Grained includes:
Silt
Clay
Gravel
Sand
22
Excavation:
removing earth
can be shallow or deep
adjusting of the ground
removed rock and soil is stockpiled
23
Particle Size: largest to smallest
Boulder, Gravel, Cobble, Sand, Silt, Clay
Boulder, Cobble, Gravel, Sand, Clay, Silt
Boulder, Cobble, Sand, Gravel, Silt, Clay
Boulder, Cobble, Gravel, Sand, Silt, Clay
24
Standard Penetration Test:
# of blows needed for the tube to penetrate each 12" up to a depth of 30"
slide hammer with a mass of 140lb falling through a distance of 30"
# of blows needed for the tube to penetrate each 6" up to a depth of 18"
slide hammer with a mass of 50lb falling through a distance of 12"
25
Volume of water to remove depends on:
elevation of the water table
type of soil
elevation of the building
the depth of the excavation
26
Rock:
strongest most stable of earth materials
smaller than silt, plate-shaped
continuous mass of solid mineral material
particulate
27
Sand:
Individual particles can be lifted between thumb and forefinger
Particles too small to individually lifted between fingers
smaller than silt, plate-shaped
spherical particles, too small to see with the unaided eye
28
Grading and Excavation Units:
backfill sq. ft
grading backfill cubic yards (CY)
grading Sq. Ft or Sq. Yd.
excavation & backfill cubic yards (CY)
29
Unrestricted Site:
usually involves sheeting excavations
area sufficiently larger than the building footprint
are constricted/limited
usually involves benching or sloping excavations
30
Generally, coarse-grained soils are less sensitive to moisture content and more stable than finer grained soils.
True
False
31
Slurry wall:
reinforces using hydrostatic pressure
used for spatially limited construction
done in steps
reinforces using slurry pressure
32
Shrinkage (%) =
1 - shrinkage
bank volume x shrinkage factor
( 1 - bank density / compacted density ) x 100
bank density / compacted density
33
Soldier Piles (beams) and Lagging:
continuous elements
more cost effective
individual elements
work around utilities
34
Shrinkage Factor =
( 1 - bank density / compacted density ) x 100
bank volume x shrinkage factor
1 - shrinkage
bank density / compacted density
35
Dewatering continues as excavation proceeds.
True
False
36
All soil types are more dense when we compact them.
True
False
37
Loose Material:
material in natural state
a unit volume is identified as loose cubic yard (LCY)
a unit volume is identified as compacted cubic yard (CCY)
material has been excavated or loaded
38
Options for dewatering:
let water in, then remove it (most cost effective)
combination of the two (most expensive)
keep water out
combination of the two (least expensive)
39
Coarse-Grained includes:
Clay
Silt
Sand
Gravel
40
Fine Grained Soil Properties:
properties and strength vary with moisture content
free-draining: good at drainging water away from foundations and structures
properties are more sensitive to moisture content
cohesionless: strength depends on friction and interlocking of particles
41
Subsurface Investigation includes:
performing a site investigation
accounting for contignecies (buried structures/things)
samples tested on field or in lab
soils/geotech report produced
42
It is common on projects with high loadings to determine:
soil strata and water table data
bearing capacity
yo mamma
yo daddy
43
Generally, the smaller the particle size, the stronger the soil.
False
True
44
Restricted Site:
usually involves sheeting excavations
usually involves benching or sloping excavations
area sufficiently larger than the building footprint
are constricted/limited
45
Sheet Piling:
more expensive
utility damage prone
can be braced or unbraced
continous elements: made out of wood, steel, precast panels
46
Soil:
the strongest and most stable of earth materials
properties vary with particle size and shape, mineral content, and moisture
particulate
too big to lift with one hand
47
Soil Samples and Testing:
information used to prepare soils report
information used to prepare stuctural general notes
scraped off the top soil
sample holes are strategically located
48
Geotech reports describe soils and properties, derived from:
test pit samples
top soil samples
boring samples
laboratory testing
49
As soil becomes more porous and/or the water table higher, sump pumps become a less viable alternative.
True
False
50
A soil has an increase in volume when it is excavated.
True
False
51
Bracing of sheet piling can include:
beams and girders
tiebacks that tie the sheets back into the soil around the excavation
crosslot bracing that uses members in a cross pattern to support the sheets
rakers that the sheets into the ground inside the excavation
52
Coarse Grained Soil Properties:
properties are not affected by moisture content
cohesionless: strength depends on friction and interlocking of particles
free-draining: good at drainging water away from foundations and structures
when confined, have little strength
53
Soil Conditions include:
load and shrinkage factors
swelling and shrinkage
particle size
Bank Material, Loose Material, and Compacted Material states
54
Considerations with Sump Pumps and Well Points:
reliability of pumping system
soil contamination migration
water discharge
surrounding water table drawn down
55
Some activities taking place on site:
surveys or impact studies
site preparation
subsurface investigation (geotech reports)
site plans
56
Classifying Earth Materials includes:
moisture content
particle size
presence of organic content
clay percentage
57
Grading and Excavation Equipment:
dozers, scrapers, wheel loaders, drill, track loader, dump trucks
trench protector, compactor, water wagon, vibratory roller
sheepsfoot compactor, compaction equip. (plate, trench sheepsfoot, tamper)
backhoe, hydraulic shovel, motor grader, rubber tracks, hydraulic hoe
58
Distribution of soils:
important for predicting load bearing capacity, stability, and drainage
usually done by adding in seperate layers of different types of soils
rarely one type - often a mixture
usually one type of soil, rarely mixed
59
Excavation and Grading Major Productivity Issues:
type of material/soil
material transportation
type of operation & equipment
expected environmental conditions
60
Clay is the most difficult to work with?
False
True
61
information in a site plan:
locations of where people like to stand and gather
results of the land survey, existing contours of the land, desired contours
locations of buildings, roads, wells, utility lines, setbacks and easements
location and size of parking spcas, streets, curbs, fences, walks, walls
62
Soil mixing:
usually used in conjuction with a reinforced cementitous coating
uses a reinforcing mat to pin soil against itself
mixing soil with concrete to make soilcrete
columns of soil strengthened with portland cement and water
63
Well Points:
size and spacing depends on volume of water
uses pumps
requires less clearance than sump pumps
perforated pipe connected to headers and discharge line
64
Well Points:
placed in the soil around the excavation
placed in the excavation
used for higher volumes of water
keep water out of the excavation by lowering the water table
65
Types of Dewatering Systems:
Sump Pumps
Hoses
Well Points
Watertight Barrier Wall
66
Sloping and Shoring depends on:
temporary or permanent and cost
proximity to buildings
soil type and water table level
site types: unrestricted and restricted
67
The sum of the number of blows req for the 2nd and 3rd 6" of penetration is termed:
standard penetration resistance
N-value
M-value
standard penetration distance
68
Soil instability can be worsened when:
vibrations
the excavation is deep
water table lowers
heavy machines around excavation
69
Soil nailing:
uses a reinforcing mat to pin soil against itself
mixing soil with concrete to make soilcrete
usually held by anchor plates and a tendon stressed into the wall of soil
usually used in conjuction with a reinforced cementitous coating
70
Boulder:
particles too small to be individually lifted between fingers
individual particles can be lifted between thumb and forefinger
too big to lift with one hand
can be lifted with one hand
71
Sheeting:
involved sloping or benching the excavation
considerations: bank erosions, water diversion, safety
types: soldier piles and lagging, sheet piling, and slurry walls
most expensive
72
Dewatering:
process of adding water or rising the water table
to provide a dry working platform
process of removing water and/or lowering the water table
to moisten the soil around the foundation
73
Benching or Sloping:
least expensive
considerations: bank erosion, water diversion, safety, storage of backfill
must have perimeter clearance
most expensive
74
Site Layout Planning is:
determining how many floors there are in the building
determining the room layout of the building
determining the elevations of the site
determining the locations of gates, storage areas, construction equip., etc
75
Water Tight Barrier Walls:
keep water out
slurry walls and sheeting with pumps
must resist hydrostatic pressure
must be impermeable
76
What determines the number of bores/tests on a site?
budget and schedule
location and prior knowledge
type of project
code requirements
77
Dewatering techniques:
a system to add water to the excavation
watertight walls that must resist hyrdostatic & soil pressure
Slurry walls or Sheet Piling
using a dewatering system to remove water from the excavation
78
Compacted Material:
material after compaction
a unit volume is identified as compacted cubic yard (CCY)
material in natural state
a unit volume is identified as a bank cubic yard (BCY)