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 New Hampshire Concrete Cutting 210 Walnut St, Manchester, NH 03104 Call Now 603-622-4440 Concrete Cutting - Core Drilling - Wall Sawing - Flat Sawing |
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Concrete Cutting Sawing Hampton Falls NH New HampshireWelcome
to affordableconcretecutters.net
“We
Specialize in Cutting Doorways and Windows in Concrete Foundations”
Are You in Hampton Falls New
Hampshire? Do You Need Concrete Cutting?
We Are Your Local
Concrete Cutter
Call 603-622-4440
We Service Hampton
Falls NH and all surrounding Cities & Towns
“No Travel Charges – Ever! Guaranteed!”
Visit Hampton_Falls, New Hampshire for a relaxing vacation It
is also assumed that the earthy material acts virtually the same as a liquid
with a density considerably greater than water; but there is ground for
believing that even this assumption is not strictly warranted. Theoretically
the problem is also very much complicated by the question of the earth pressure
which may be produced by a surcharged wall. A surcharge is a bank of earth
which is built above the height of the top of the concrete retaining concrete
wall and sloping back from it. It certainly adds to the pressure on the earth
immediately back of the concrete wall itself and increases the pressure on the
wall. In spite of the unreliability of theoretical mix, for the reasons given
above, certain mix which are here quoted without demonstration are sometimes
used for lack of better concrete mix, a guide in determining the thickness of a
wall. For simplicity it is assumed that the rear face of the concrete wall is
vertical. The variation in the theory by attempting to allow for a slope of the
rear face, merely complicates the theory; while the effect of such a variation
from the vertical as is ever adopted is usually so small that it is utterly
swallowed up by the unavoidable uncertainties in the practical application of
the theory. Total pressure against rear face of concrete wall on a unit-length
of wall; w = Weight of a unit-volume of the earth; the angle of repose with the
horizontal—that is, the angle at which that kind of earth will remain without
further sliding. An inspection of Equation 6 will show that the pressure E is
greater for small values of ci: The angle of repose
for various materials is not only variable for different grades of material,
but is variable for the same grade of material under various conditions of
saturation. A value of ci which is frequently adopted is 300.
This
is considerably lower than the usual true value of ci for dry material, and is usually a safe value of ci for any material (except quicksand) either wet or dry. The adoption of this
value, therefore, generally means that the result is safe, and that the factor
of safety is merely made somewhat larger. What will be the pressure per foot of
length of the wall, for a concrete wall 18 feet high, the angle of repose for
the earth being assumed at 300?
The
weight of earth (w) is quoted as varying from 70 to 120 pounds per cubic foot
according to the degree of saturation and density of packing. When the earth is
densely packed, its angle of repose is greater; therefore we are safe in
assuming a weight of 100 pounds per cubic foot for an angle (c) of 30°. Using
this value of c = 30° gives us the simple relation that E = w h3, or one-sixth
of the unit-weight of the earth times the square of the height, for a concrete
wall without a surcharge. There are four distinct ways in which failure of a concrete
retaining concrete wall may come about:
(1)
A concrete retaining wall may fail by sliding bodily on its foundations or on
any horizontal joint. This may occur when the concrete wall is resting on a
soft soil, and especially when the foundation is not sunk sufficiently deep
into the subsoil so that it is anchored. The failure of the concrete wall on a
horizontal joint is very improbable when the concrete cutting work and its
bonding are properly done. Perfectly flat, continuous joints should be avoided.
(2)
A concrete retaining wall may fail by crushing the toe of the wall. This may
occur, provided that the resultant of the weight of the concrete wall and of
the overturning pressure comes so near the toe of the wall, and the intensity
of that pressure is so great, that the concrete cutting is crushed. The method
of calculating such pressure will be given later.
(3)
The concrete wall may fail by tipping over. This may occur provided that the
resultant pressure (described later) passes outside the toe of the wall.
(4)
The same effect occurs provided that the subsoil is unable to withstand the
concentrated pressure on the toe of the wall, and yields, while the concrete
cutting of the concrete wall may nevertheless remain intact and the concrete
wall itself be properly proportioned.
Are You in Hampton Falls New
Hampshire? Do You Need Concrete Cutting?
We Are Your Local
Concrete Cutter
Call 603-622-4440
We Service Hampton
Falls NH and all surrounding Cities & Towns
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