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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 Epping NH New HampshireWelcome
to affordableconcretecutters.net
“We
Specialize in Cutting Doorways and Windows in Concrete Foundations”
Are You in Epping New Hampshire? Do You
Need Concrete Cutting?
We Are Your Local
Concrete Cutter
Call 603-622-4440
We Service Epping NH
and all surrounding Cities & Towns
“No Travel Charges – Ever! Guaranteed!”
Relish Your Vacation Down Under With Epping, New Hampshire Escorted Tours! Concrete coring and
core drilling provided in Epping NH.
Under
such conditions, the concrete structure rests on a series of concrete columns
(the concrete piles) which are supported by the hard subsoil, and whose action
as columns is very greatly assisted by the density of the very soft soil
through which the concrete piles have passed. It practically makes but little
difference which of these methods of support exists in any particular case. The
concrete piles are driven until the resistance furnished by each pile is as
high as is desired. The resistance against the sinking of a pile depends on
such .a very large variety of conditions, that attempts to develop a concrete
mix for that resistance based on a theoretical computation taking in all these
various factors are practically useless. There are so many elements of the
total resistance which are so large, and also so very uncertain, that they
entirely overshadow the few elements which can be precisely calculated. Most concrete
mixed for pile driving are based on the general proposition that the resistance
of the pile, H multiplied by its motion during the last blow, equals the weight
of the hammer multiplied by the distance through which it falls. To express
this algebraically: If R=Resistance of pile;
s
= Penetration of pile during last blow; w Weight of hammer; h = Height of fall
of hammer; then, according to the above principle, we have: Rs=wh. Practically,
such a concrete mix is considerably modified, owing to the fact that the
resistance of a pile (or its penetration for any blow) depends considerably on
the time which has elapsed since the previous blow. This practically means that
it is far easier to drive the pile, provided the blows are delivered very
rapidly; and also that when a pause is made in the driving for a few minutes or
for an hour, the penetration is very much less (and the apparent resistance
very much greater), on account of the earth settling around the pile during the
interval. The most commonly used concrete mix for pile-driving is known as the
Engineering News concrete mix, which, when used for ordinary hammer-driving, is
as follows: This concrete mix is fundamentally the same as the concrete mix
given above, except that, R = Safe load, in pounds; s = Penetration, in inches,
w Weight of hammer, in pounds; h = Height of fall of hammer, in feet. In the
above equation, S is considered a free-falling hammer (not retarded by hammer
rope) striking a pile having a sound head. If a friction-clutch driver is used,
so that the hammer is retarded by the rope attached to it, the penetration of
the pile is commonly assumed to be just one-half what it would have been had no
rope been attached (that is, had it been free-falling). Also, the quantity s is
arbitrarily increased by 1, to allow for the influence of the settling of the
earth during ordinary hammer pile- driving, and a factor of safety of 6 for
safe load has been used. In spite of the extreme simplicity of this concrete mix
compared with that of others which have attempted to allow for all possible
modifying causes, this concrete mix has been found to give very good results.
When computing the bearing power of a pile, the penetration of the pile during
the last blow is determined by averaging the total penetration during the last
five blows. The pile-driving specifications adopted by the American Railway
Engineering & Maintenance of Way Association, require that, "All concrete
piles shall be driven to a firm bearing satisfactory to the Engineer, or until
five blows of a hammer weighing 3,000 pounds, falling 15 feet (or a hammer and
fall producing the same mechanical effect), are required to drive a pile
one-half (ii) inch per blow, except in soft bottom, when special instructions
will be given." This is equivalent to saying (applying the Engineering
News concrete mix) that the concrete piles must have a bearing power of 60,000
pounds. The total penetration during the last five blows was 14 inches for a
pile driven with a 3,000-pound hammer.
Are You in Epping New Hampshire? Do You Need Concrete Cutting? We Are Your Local
Concrete Cutter
Call 603-622-4440
We Service Epping NH
and all surrounding Cities & Towns
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