Pipe & Excavating Flashcards
Bank Cubic yards (BCY)
Soil resting in its natural, undisturbed condition
Loose cubic yards (LCY)
When soil is excavated or in some wat disturbed from its natural state, it swells, increasing in volume
Compacted cubic yards (CCY)
When soil is compacted, it shrinks, decreasing in volume.
Optimum hourly production rate for excavation equipment formula
Number of completed cycles per hour x volume of material moved each cycle
Struck capacity
Represents bucket contents when filled to the level of the rim, with no material heaped over it. Struck capacity is the same as the water-carrying capacity of the bucket.
Load Factor - excavation equipment performance
Captures another facet to soil swell - essentially converts loose cubic yards to bank cubic yards -
Bank volume / (bank volume x 1.25)
Load Factor for Sand - Dry, loose soil
0.89
Load Factor for Sand & Clay - Loose Compacted
0.79
Production for a track excavator cycle times are longer because
it takes more time to maneuver around obstructions like trees and power lines
What are the four operations of a loading project?
excavation, loading, hauling and backfilling
When should track loaders be utilized for a project (versus a wheeled loader)?
Where good traction and reduced ground pressures are required. Where working surfaces are abrasive enough to cause excessive tire wear.
What is the most common bulldozer used for?
The light utility dozer with applications for residential and commercial foundations, fine grading, trench backfill, landscaping, light logging and swamp dozing.
What dozer skill and technique has the biggest influence on dozer efficiency?
Blade position and depth of cut are the primary. The direction of the dozing pass, gear selection, travel speed and the slope on which the machine is working are also variables.
What is the ideal travel speed for initial blade loading on a dozer?
1.5 mph
1.5mph - 4mph is the practical maximum
How much does the blade capacity increase when pushed down a negative 40% grade?
load capacity on the dozer blade doubles
When slopes are greater than 60% for a dozer, they are called?
Knee Shakers
What is the rule of thumb for dozer speed?
Average dozing speed under load is 2mph
When the machines isn’t under load it will be 4 to 5 mph
What is a blue top in finish blading?
When a road base or site is approaching the correct grade level, engineers place hubs at the exact finish elevation. The grader operator cuts just to the top of the hub and no farther.
Which piece of equipment is the most cost-efficient earthmover available?
With the exception of extremely large excavators, scapers (pans)
Scraper load time is dependent on what variables?
- The size, power and type of scraper
- The amount of pusher power that’s available
- Soil condition, traction, and total resistance
- Traffic at the cut
- Operator skill
Pushers are often used in tandem to increase loading rate. What is the rate?
Each pound of push (including the scraper’s effort) loads one pound of soil into the bowl per minute of load time.
Survey Cut
A cut (C) is always lower than the reference point
Survey Fill
A fill (F) is always higher than the reference point
What is a survey hub?
A small stake driven into the ground to identify some reference point. Near the bub will be a reference stake, which identifies the hub’s elevation and situation in relation to the pipeline.
Expressing slope as a ratio in surveying
Horizontal distance: Vertical distance
What are the two most common back-hoe controls
Right joystick:
Close bucket (left)
Open bucket (right)
Backhoe production rate: time required to excavate a set =
Digging cycles per set X average cycle time
Backhoe production rate: digging cycles per set
Volume of dirt in set X dirt moved per cycle
Which backhoe specializes in digging trenches up to about 8’ deep?
The tractor-loader-backhoe
What are the four steps in excavating around a crossline?
- Remove the dirt from behind crossline
- Remove dirt piled against back of pipe
- Excavate in front of crossline
- Remove loosened dirt under crossline
Formula to calculate a sheepsfoot roller compaction idea output on a CCY/HR basis
(roller width(ft) x speed(mph) x compacted lift thickness(in) x 16.3) / number of passes
Silt and clay require a precise combination of all of the following Except? (weight, vibration, air, moisture)
Air
Typically, solid rock will have a minimum angle of repose of ____ degrees.
90
Since each soil type has a different weight-to-volume ratio, the proctor test find the point taken is at ____.
100% density and optimum moisture content for the soil that is being compacted.
Except for extremely large excavators, _________ are the most cost-efficient earthmovers available.
Scrapers (pans)
