Site Work Flashcards
soil is classified into these 4 gorups
sands/gravels
silts
clays
organics
this soil has low plasticity, good for foundations/drainage
sands/gravel
this soil is good for foundations if stable
clay
this soil is better mixed with other types of soil
clay
this soil has tensile strength, and is slightly plastic
clay
this soil is a poor foundation
organics
an unbroken mixture of clay, sand, and gravel
hardpan
highest bearing capacity
bedrock
broken off bedrock
boulders
second highest bearing capacity
shale/slate
soft rock with a fine texture
shale/slate
a soil test typically determines
bearing capacity,
water table level,
porosity
administers soil test
soils engineer
typically recorded in boring log
material/ depth it is encountered/ moisture content/
density
boring location: minimum #
4, taken at corners
boring locations are shown on
plot plan
boring location #’s on plot plan correspond to
boring logs in soil test report
soils report contains
allowed soil bearing pressure and foundation type
lab tests:
specific gravity
determines void ratio,
used for compressibility
lab tests:
grain size and shape
determines shear strength,
permeability,
compaction ability
lab tests:
liquid and plastic limits
compaction and compressibility
lab tests:
unconfined compression
shear strength for cohesive soil
lab tests:
water content
used to get compressibility,
and compaction values for cohesive soil
most common site tests
boring,
and
test pit
most common borehole test
SPT
Standard Penetration Test
SPT tests
density of granular soils
and consistency of some clays
physical tools and process for SPT
2”ø sampler /
140lb hammer /
falling 30”.
recorded in SPT: # blows required to
drive cylinder 12”
site test:
visual inspection,
10’ depth limit typ.
Test Pits
site test:
best in sand/clay
shallow/intermediate depths
no hard obstructions (bedrock/hardpan)
Auger Boring
site test:
when soil too hard for auger bit
100’+
Wash Borings
problem with wash borings
samples too mixed, analysis difficult
site test:
pipe, 5” increments
Dry Sample Borings
site test:
Soil Load Tests
platform, incremental loads, settlement holds, with continued loading. design load usually ½ test load
site test: Soil Load Tests
design load is typically ____
½ test load
soil types are classified by
Unified Classification System
bearing capacity is generally specified by ______ ,
based on ______
building code,
based on soil type
building code bearing capacity can be increased if
appropriate test evidence
water in soil can
reduce load carrying capacity
if more moisture under one area of building than another
differential settlement may occur
soil treatment is used to
increase bearing capacity, and/or decrease settlement
in order to compact fill,
water is required to lubricate
optimum relationship between fill density/moisture content
determined in lab by
Proctor test
“standards for compaction.”
Proctor test
Fill compaction:
density ___% of optimum Proctor density req’d
90-100%
Fill compaction:
moisture content __% of optimum @ time of compaction.
2-4%
Fill compaction:
fill in ____” layers (called ‘lifts’), compacted, then next layer.
8-12”
Soil Treatment:
Surcharging
preload with fill / settle soil below / remove fill.
Soil Treatment:
Mixing
sand/gravel added to create req’d properties.
Earthwork:
term for when narrow/long for pipe/narrow footings
trenching
Excavation:
for safety, sides no steeper than
than natural angle of repose
or not > 1.5H:1V
Rough Grading tolerance
±6-12” of desired finish level
Finish Grading tolerance
±1” desired level, includes placement of topsoil
Parts of Beam and Timber shoring method
soldier beams/
breast boards or cribbing/
tiebacks
Parts of Sheating and Brace shoring method
Vertical sheeting (wood/steel)/
horizontal wales,
diagonal rakers (bracing),
concrete/steel heel.
Underpinning is used when
temp. supporting exist’g foundations
perforated drain tile (“french drain”) min _” below floor slab
6”
if hydrostatic pressure use
layer of gravel
open web matting/
geotextile mat’l
if pressure @ floorlab use
use waterproofing membrane,
gravel layer w/ drain tiles.
min. slope of ground for drainage
1/4” per ft.
drain inlet vs. catch basin
catch basin has sump,
cleaned out periodically.
large storm sewers require manholes,
every direction change or 500 ft max.
Concrete paving is reinformed with
welded wire fabric
Concrete paving min. thickness
5” min.
Concrete paving poured in sections, w/ joints every
20’ (½” molded joint filler)
hot-laid asphalt:
most common
asphalt cement + graded aggregates,
laid on a base, rolled + compacted while still hot.
cold-laid asphalt:
subbase coarse gravel, overlaid w/ finer aggregate, compacted, rolled.
2-3” cold liquid asphalt laid over-top.
Unit paver procedure
laid on level, compacted sand over crushed gravel
may also be laid over bituminous bed on concrete slab.
Concrete Walks: laid over gravel subbase, control joints every _’, expansion joints every _’
control joints every 5’,
expansion joints every 20’
