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newbie faq on earthwork

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longisland

Geotechnical
Sep 25, 1999
82
Hi all,
I am new to earthwork & my questions are as follows:-
1) What are the tests & measures required for monitoring earthwork?
These are the steps taken in a job I supervised; before carrying out any work, tests are conducted from extracted samples at the borrow source to determine namely, the particle sizes by means of gradation tests, moisture content to determine if the soil may be compacted or not, bulk & dry & bulk desnity, & organic content tests if necessary. Field survey is conducted to ensure the spot levels on site tally with the construction plans & to peg out the construction limit.
Site clearance of minimum 300mm is done to remove the top soil, unsuitable & vegetation.
Spot levels are then recorded before earthfilling starts.
A trial lay and compaction is done by laying 9 to 14 inch earth and then compact to 6 inch. Field density test is then carry out to ensure the compaction reaches 95% MDD. Work is then carry out in subdivided areas. Temporary drains are constructed to make sure ther's proper discharge during rain. Field density is carried out after every layer of compaction. Spot survey and insitu CBR tests are conducted when job is completed followed by turfing if the embankment fill is high (6m) or if the area is susceeptible to rain.
The FDTs are done in every 50 square meters. I took 3 samples from the source for every 500 trips. The site is about 100 acres & the source is about 10 km away.

2) As a rule of thumb, earthfilled embankments have slopes ranging from 1:1.5 to 1:3; how do these values come about? what are the tests and design parameters required for the design of the slope?

thanks

longisland
 
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Man, your lookin for a whole lot of trouble...lol

Monitoring and testing earthwork is usually set
by governing statuts. The slopes are calced by
designers or engineers usually. The slope is based
on the slope strength of the soil, type of soil,
if engineered fill will be placed, amount
of flow coming into the embankment, amount of flow
on or in the swale, and whether rip rap or other
materials need to placed in or on the embankment.
 
It seems you may have missed one important step - after stripping 300mm, but before placing embankment, was there any check to see if the existing ground was suitable for placing embankment? Usually a geotech report or inspection would determine this, and proof rolling might provide some quality assurance that the subgrade is dense and compact and suitable for placing fill.

to obtain proper compaction moisture control is important. Especially if you have finer grained or plastic soil.

You also need to maintain best management practices (bmp's) for temporary drainage in order to comply with your NPDES permit. I also suggest stockpiling and replacement of the topsoil, and minimal compaction of this topsoil where grass is expected to grow.

Chuck
cgopperton@stantec.com
 
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