Earthwork Test 1

What does the geotechnical engineer prepare for soil and construction management?

-Soil testing reports

-design alternatives

-equipment reccommendations

What does the project manager?

-match the design/scope with available resources

-select the equipment

-design the work sequence/schedule

-monitor the progress and adjust operations as necessary

What are three soil types?

-granular

-cohesive

-organic

Granular Soil

-smaller 3D versions of parent rock

-strong and relatively stable

-from boulders to silt

Cohesive Soil

-Small flat 2D particles

-React with water

-Clays

Organic Soil

-organic materials

-decay over time

-peat and muck

-odor

What do you have to worry about with clay?

moisture

What do you have to worry about with sand?

dryness

Who pays for the Geotech report?

owner

What are "problem" soils?

-reactive clays

-soft soils

-sink holes

When do you use organic soils?

topsoil

what are the three types of soils identified in a sieve analysis?

-continuous

-uniform

-gap

continuous soil

-compacts well and fits together like puzzle

uniform soil

does not pack together well

gap soil

compacts better than uniform soil but still has air gaps

#4 sieve is where soil changes from gravel to what?

sand

#200 sieve is where soil changes from sand to what?

clay

With the Unified Soil Classification System, each soil is given a ___ - _______ classification.

2 letter

Soil Symbol: G

gravel

Soil Symbol: S

Sand

Soil Symbol: M

Silt

Soil Symbol: C

Clay

Soil Symbol: O

Organic

Soil Symbol: Pt

Peat

Plasticity Symbols

- H: High Plasticity

- L: low Plasticity

Gradation Symbols

-W: Well graded

-P: Poorly graded

SW soil would be what classification of soil?

Well-graded sand

SC soil would be what classification of soil?

clayey sand

SM soil would be what classification of soil?

silty sand

MH soil would be what classification of soil?

Highly Plastic Silt

What is the main criteria used to classify fine grained soils (silt and clay)?

soil plasticity

Soil plasticity largely depends on:

-moisture content

-type of clay mineral

T/F: Two soil samples having approximately the same size particles may behave differently based on the amount of their existing moisture content.

True

Atterberg Limits

The arbitrary limits which define the boundaries between the different states of fine-grained soils

Shrinkage Limit

a moisture content at which the soil changes from a solid state to a semi solid state

If moisture content is less than the shrinkage limit, then _______________.

there is no volume reduction upon drying

Moderate Shear Strength in Soil

soil is stable and can support low to moderate loads

Plastic Limit

The moisture content at which a soil starts to change from a semisolid to a plastic state

Plastic Material

one that deforms readily without cracking or crumbling

Low Shear Strength in Soil

soil deforms easily under loads

Liquid Limit

-moisture content at which the soil changes from a plastic state to a liquid state

-the water content at which the soil has negligible shear strength

Clay flows like liquid when the moisture content is _______ (greater than, less than) the liquid limit.

greater than

Plasticity Index

Ramge of water content over which the soil remains plastic

Plasticity Index=

Liquid Limit-Plastic limit

Compaction

density of soil by the application of mechanical energy (removing the air)

Why is soil compacted?

-to increase soil strength

-to improve the stability of the soil

-to reduce soil permeability

-to reduce erosion damage

What are the factors affecting compaction?

-water content

-compacting effort

-type of soil

-method of compaction

Liquidity Index is especially important when building in ____ zones.

earthquake

Why is soil compaction important?

- ALL construction work is ultimately supported by soil

- Improperly compacted soils can lead to structural failure

Fill is usually placed in _____ or ______.

lifts, layers

Utility trenches typically have lifts in what increments?

4-inch

Large fill areas typically have lifts in what increments>

6-12 inch lifts (dependent on density requirements, type of soil, and compaction equipment)

Why is it important to scarify or disk the top of a lift that has just been placed before placing next lift?

-prevents laminations

-Ensures uniform compaction

Density requirements in the contract specifications

-expressed as percentage of maximum dry weight

-max dry weight determined by a proctor test

-Proctor Test ASTM 698

Proctor Curve

When do pumping soils occur?

when the moisture content of clayey or silty soils gets too high, they begin to pump when compacted

Bank CY

material in its natural state

Loose CY

Material that has been excavated

Compacted CY

material after it has been compacted

What is the most common method to get cubic yards for earthwork construction?

average end area method

Typically, excavation (cut) is paid for in what unit of measure?

Bank Cubic Yards

Typically, fill is paid for in what unit of measure?

compacted cubic yards

T/F: Hauling soil, haul road maintenance, equipment maintenance, etc. is paid for separately from cut and fill cost.

False. The cost of these activities is included in the unit prices for cut and fill.

What equipment is used to spread material?

dozers

What equipment is used to compact cohesionless soil?

vibratory roller

What equipment is used for cohesive soil?

sheepsfoot roller

What equipment is used to aerate soil?

disks

What equipment is used for sand?

pneumatic roller

What are the objectives of field explorations?

-locate and define vertical and horizontal boundaries of various soil and rock strata under the site

-locate the groundwater table

-determine the engineering properties of the soil (in undisturbed and disturbed state)

What are the benefits of field explorations?

-substantially assist a contractor in preparing a bid

-performed by third party engineers on the request of the owner

-In government projects, owner and engineers may belong to the same organization

Soil Data Obtained During Field Explorations

-Soil Profile

-Index Properties

-Strength and Compressibility Characteristics

-Others

Soil Profile

Layer Thickness and Soil Identification

Index Properties

water content, Atterberg limits, etc.

Strength and Compressibility Characteristics

Shear Strength and Bearing Capacity

Other Data Obtained During Field Explorations

Water table depth, presence of debris or utilities, etc.

Spacing of borings for a multi-story building

50-100ft

Spacing of borings for a one story building, earth dam, and borrow pits

100-200ft

Spacing of borings for highways(subgrade)

500-1000ft

Standard Penetration Test Correlations in Granular Soils

Standard Penetration Test Correlations in Clays

NPDES Phase I

1990 - EPA began requiring large and medium municipalities, many industries, and construction sites greater than 5 acres to obtain NPDES storm water permits

NPDES Phase II

- 1999 - EPA began requiring small municipalities and small construction sites between 1 and 5 acres to require permits - - Phase II covers 75% of construction Industry

SWPPP

-Storm Water Pollution Prevention Plan

- site-specific, dynamic plans that describe and dictate

what measures will be used to control erosion and prevent

sedimentation from leaving a construction jobsite

Why are SWPPPs important?

-dynamic measures taken to keep every inch of soil contained on a jobsite

-Construction professionals need to have a full

understanding of the erosion process to grasp the importance of erosion and sediment control on a

jobsite

Who monitors SWPPP?

-federal government

-state and regional government

-county/city regulations

-construction site owners and operators

-specialty contractors

Erosion

-is the process by which the land surface is worn away

by the action of wind, water and gravity

-is natural and can be accelerated by man

sedimentation

the settling of soil particles transported by wind and water

Erosion control is _______, while sediment control is ________.

proactive, reactive

Good erosion control plan effects:

erosion can be limited to not more than 2% over natural causes of erosion

Bad erosion control plan effects:

-job cost increase

-potential jail time

-loss of job

Buffer Zone

the use of a vegetated strip of land bordering a water body or wetland to reduce sediment and nutrient impact of sheet erosion flow

Stabilized Fiber Matrices and Hydro-Seeding

-Spray of Biodegradable man-made fibers, grass seed, fertilizer and water

- spray effective after 1-hr drying & will control erosion and sedimentation

Erosion Control Blankets

- Plant fiber erosion control blankets most common.

- Erosion control blankets widely used on large projects with steep slopes or anywhere slope stabilization is needed.

- Easy to install and come

- in rolls that range from 3' to custom rolls of 40'

- Most common width is 3'-4'

Types of Sediment Control

• Straw Wattles

• Silt Fence

• Drain Inlet Devices

• Fiber Filtration Tubes

• Rock Check Dams

• Construction Site entrance rip-rap

Silt Fence Effectiveness and Installation

-Most common BMP

-Often fail due to improper installation

-should be checked and maintained often

-cleaned when sediment has accumulated to almost half of the fence's height

Silt Fence Failure Modes

-Poor Maintenance

-By-Pass

-Improper Installation

-Undercutting

-Silt By Pass

-Overtopping

Construction Entrance/Exit Stabilization purpose

to reduce erosion of temporary roadbeds (haul roads) and parking areas prior to final stabilization of the site

Rock Check Dams

-reduce velocity of concentrated flows of storm water in ditches and on slopes

-must be frequently cleaned of debris

Sediment Basins

-Capture, detain, treat stormwater prior to offsite

discharge

- Contain suspended particles found in stormwater runoff

- Treatment through gravitational settlement

- Contained water must remain long enough for deposition of suspended particles to occur

- Install before other grading operations begin

T/F: The bottom of the top check dam needs to be same height as the top of the lower check dam.

True