Ihab Saad – Soil Properties
AI: Summary ©
The speaker discusses earth moving equipment and soil properties, including solid particles and voids in earth, and how to measure the weight and density of soil using calculations based on weight and volume. They also explain how to calculate the weight and proportion of water in a compacted or undrilled soil, and provide examples of measurements used to determine these measurements. The speaker emphasizes the importance of using these measurements to determine the weight and density of different types of dirt and provides examples of how these measurements can be used to determine the weight and density of different types of dirt.
AI: Summary ©
Music. Hello again, and welcome to
construction measurement 329,
construction equipment.
So today we're going to start talking a little bit
about earth moving equipment and soil properties. So we need to
know about some of the properties of soil before we start discussing
any details on the equipment itself.
So things you should have learned in soils class, have you been
paying attention? Any mass of soil consists of solid particles with
voids in between,
whether it's rock, whether it's sand, clay, any type of soil. It's
soil particles with voids in between, and these voids can be
filled either with water or air. If it's submerged or under the
water table, then the voids are going to be filled with water
then. Or if it's above the water table and not submerged, then it's
going to be filled with air,
just having a look at this graph shows basically what we're talking
about.
It has solid
solids, and then again, if partially submerged, it's going to
have water and it might have air. All of this may be filled with
water if it's totally submerged, and all of this is going to be
filled with air if it's not submerged at all. And these can be
measured either by volume or by mass. So looking at the volume we
have VT, which is the total volume of that sample of soil, with vs
being the volume of solids. And VV is the volume of voids, which can
be divided into VW, volume of water and VA, volume of air. On
the other hand, if we measure it by mass, then MT is the total
mass. Notice here that MT is not up to the top, because air doesn't
have any mass. Ma is equal to zero, so MT is going to be just
equal to MS, the mass of soil, the solids and MW, the mass of water.
If you want to calculate the weight of that soil, the unit
weight is going to be the total weight of the soil divided by the
total soil volume. So w over V, we get a soil sample we weight, and
then we divide that weight by the volume, and that gives the unit
weight, or the density of that soil dry unit weight, however, yd
is going to be basically the weight of the soil solids,
excluding the water. So we put it in the oven to try it and get rid
of all the included water. And then we weigh the solids divided
by the same volume, which is going to be total soil volume. And that
gives us the dry unit weight,
the moisture content, which is the amount of moisture in that soil,
is going to be
calculated as the wet unit weight minus the dry unit weight, again,
by drying the soil in an oven getting rid of the water. So wet
unit weight minus dry unit weight, which is basically the weight of
water times 100%
divided by the dry unit weight. It can range from 0% if the soil is
totally dry in a desert or something like that, to several
100% because in some cases, the weight of the water and the volume
of the water can exceed the volume of solids themselves. So in this
case, it can be more than 100%
water content for most soils is well under 0%
although it can range up to 500% or higher in submarine and organic
soils, soils that can hold a lot of water, or soils that are
totally submerged as marine soils.
Now looking at an example for these calculations. Excavated
material has a wet weight, wet unit weight of 94.3
pounds per cubic foot, that's PCF, and a dry unit weight of 87 point
3.3,
PCF, and the embankment will be compacted to a dry weight of 114
pcf. Compacting the soil means getting rid of the voids totally,
or to a certain level. So getting rid of the air,
making the soil particles come closer to each other, and the
desired water content is 12%
the next section of the embankment is 115,000, cubic yards. What type
of cubic yards we're going to discuss that in a minute? What is
the moisture content of the excavated soil? How many cubic
yards of excavation will be required to construct the
embankment, and do we need to add.
Five. So this is going to be times 100 plus 20 525.
Divided by 100% minus percent shrinkage. So this way we can
convert. If I know the compacted volume, I can get and knowing the
swell and the shrinkage percentages, I can get the loose
volume, and I can get the bank volume also. So we can convert
between these three different types, knowing these two equations
to
look at an example here, a soil weighs 19 160
pounds per loose cubic yard. Now notice that this is loose cubic
yard, which means when we excavate it, when we disturbed it after the
excavation, that was the weight, as it was measured, and it's not
in its natural condition, is 2800 pounds per band cubic yard and
compacted. Now again, the density is going to increase. So the
weight per unit volume is going to increase. 3500 pounds per
compacted cubic yards. How many bank cubic yards and compacted
cubic yards are contained in 1 million loose cubic yards? Again,
based on the equations that we just learned
to get the bank volume, we multiply the loose cubic yards,
the loose volume times the loose density divided by the bank
density, and that gives us 700,000 bank cubic yards. To get the
compacted volume. We notice that it's going to be even much less
than that, which is going to be 560,000
compacted cubic yards, that shows you the amount of compaction that
this soil is going to go through. So that tells you how much more
soil do we need to bring from out of that site, just to compact,
to fill the holes that resulted from the excavation.
Another example here in building a parking lot for a new school,
10,000 compacted cubic yards are required for the fill.
The contractor has selected the source for the fill and found out
that the bank density is going to be 2800
pounds per cubic yard.
What kind of cubic yards in this case? Well, the question is told
is is given here. The answer is given, bank density. So this is
going to be bank cubic yards. The loose density is 2240
pounds per cubic yard, also loose cubic yards. And the compacted
density is 3415
pounds per cubic yard, in this case, CcY
compacted cubic yards. He plans to excavate the fill material with a
wheeled loader and load dump trucks that will haul the soil to
the construction site.
What is the percent swell for the fill material? What's the percent
shrinkage for the feed material, how many loose cubic yards must
be? Must the contractor haul in the dump trucks? How many bank
cubic yards must the contractor excavate with the loaded so again,
from this information, we can answer all of these different
questions.
First step is to calculate the swell and the shrinkage from these
different numbers using the equations that we already learned
about. So the percent swell is 25%
the percent shrinkage is 18% based on these two different
calculations.
So how many loose cubic yards must the contractor haul in the dump
trucks? The volume loose is going to be the volume compacted again
using the same equations that we learned about before, times 100%
plus percent swell divided by 100%
minus percent shrinkage, so is going to be 10,000 that's the
compacted volume that we know about, times 125%
divided by 82%
and that gives 1500 15,224
new loose cubic yards. So when you measure the soil on the trucks,
which is going to be loose, this is the volume that you need to
bring to the site.
How many bank cubic yards must the contractor excavate with the
loader again to achieve these loose cubic yards? So it's gonna,
it's gonna be that that volume 12,000 195
bank cubic yards are going to produce 10,000 compacted cubic
yards.
And that's the end of this. This lecture about soil properties.