Note: Descriptions are shown in the official language in which they were submitted.
768Z~
This invention relates to a method of planting a rod-
shaped member in a foundation such as a rock or concrete base.
mhis method is especially useful for plantation of an anchor bolt
which has to bear a large tensile force, for example, in building
construction.
In case of planting an anchor bolt in a foundation in
accordance with the prior art, it has been the general practice
to bore a hole in the foundation~ put the bolt therein and then
fill the remaining space in the hole with a filling material such
as cement or mortar. However, such prior art techniques have not
been advantageous in that it is necessary to bore a very deep
hole in order to achieve the allowable strength required under
the Industrial Standard and that it takes a significantly long
time for the filling material to harden and exhibit sufficient
strength. In addition to the laborious and time-consuming work,
it has been almost impossible to correct the position of the
bolt after filling the hole with the filling material.
Accordingly, an object of this invention is to provide
a novel and improved method for planting a rod-shaped member,
such as anchor bolt, in a foundation, such as rock or concrete,
which can greatly improve facilitation and efficiency of work
and reduce the term thereof, by removing the above-mentioned
disadvantages.
According to this invention, the method of planting
a rod-shaped member in a foundation comprises the steps of
forming a hole which is greater in cross-section than said rod-
shaped member in said foundation, putting said rod-shaped
member in said hole, filling the remaining space in said hole
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:~0'763~24
with a plurality of ball-like members which are substantially
uniform in diameter and a hardenable resin material, and harden-
ing said resin material.
Other objects and features of this invention will be
described in more detail hereinunder with reference to the
accompanying drawings and in conjunction with some examples.
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IN THF DRAWINGS:
Figure 1 is a schematic cross sectional view representing
a threaded bolt planted in a base rock according to an
embodiment of this invention;
Figure 2 is a schematic cross sectional view representing
a threaded bolt planted in a concrete base according to
another embodiment of this invention; and
Figures3(A) and 3(B) are similar cross sectional views
representing two kinds of bolts planted in a concrete base
for comparison test.
E MPLE 1
Referring to Figure 1, a cylindrical hole 1 having an
inner diameter of 42 millimeters and a depth of 250 milli-
meters was formed in a base rock 2 using a boring machine.
After cleaning the interior of the hole with a vacuum cleaner,
a threaded bolt 3 having an outer diameter of 16 millimeters
and a length of 330 millimeters was inserted in the hole 1.
Alumina ceramic balls 4 each having a diameter of about 5
millimeters, the balls being available commercially for use
in a ball-mill pot, were put in the hole 1 to about one third
of the depth of the hole to cause the bolt 3 to become self- -
supporting, so that position correction of the bolt could be
ef~ected easily. After correcting the position of the bolt 3, ~ -
a composition consisting of epoxy resin of bisphenol A
(2,2-bix(4'-hydroxyphenyl) propane) type as main component and
m-xylylenediamine as hardener was poured in the hole 1 to the
same level as the balls 4. Then, similar balls 4 were added
in the hole 1 to the surface of the base rock 2 and the same
composition was poured to the same level as shown. Although
a part of the balls were omitted from the drawing for speci-
fication, it should be noted that they are completely packed
in the space of the hole 1. Thereafter, a final correction
of the bolt position was executed and the structure was left
; as it was for about 72 hours at room temperature to harden
the resin composition.
A tension test was carried out by clutching the bolt 3
to pull it out, and resulted in breakage of the bolt at
7,500 killograms.
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~'768Z~
~ hen the same test was carried out using conventional
mortar as the filling material, the bolt was easily pulled
out without breakage of either -the bolt or the hardened mortar.
In order to obtain the same resul-t as this example, it was
necessary not only to make the depth of the hole more than
three times in order to afford the necessary frictional
resistance of the bolt but it was also necessary to greatly
increase the diameter of the hole to facilitate pouring the
mortar having much lower fluidity.
EXAMPLE 2
Referring to Figure 2, a square hole 11 was previously
formed in a concrete foundation 12. The hole had a depth
of 350 millimeters and a square cross-section of 100 x 100
millimeters. An anchor bolt 13 having an outer diameter of ~-
25 millimeters and a length of 450 millimeters was planted
in the hole 11 with the filling material of 10 millimeter
glass balls 14 and a resin composition similar to that of
Example 1. The plantation procedure was substantially similar
to that of Example 1. After the resin composition was
hardened for about 72 hours, a motor base (not shown) was fixed
by the bolts 13 on the foundation and rotation of the motor
was started immediately. Trouble has not been encountered
and the ir.stallation has already been functioning for three
months.
EXAMPLE 3
Referring to Figure 3(A), cylindrical holes 21 were
~ formed in a concrete foundation 22. While the diameters of
; the holes 21 were maintained at 42 millimeters, depths of 200,
300 and 400 millimeters were used. Steel bolts 23A each having ~`
a diameter of 16 millimeters and a tensile strength to about
45 killograms per square millimeter and being threaded over the
whole length was planted in each hole with filling materials
of 6 millimeter alumina ceramic balls 24 and an epoxy resin
composition used in -the above examples. The plantation process
was carried out in the same manner as in Example 1.
Another group of specimens was prepared similarly to the
above except that each steel bolt 23B was not threaded over the -;
lower portion to be embeded in the hole as shown in Figure 3(B).
Six specimens were prepared for each specific condition
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and tensile strengths were measured after 72 hours for the
specimens 1, 2 and 3 and after 168 hours for the specimens
4, 5 and 6. The result of the measurements was summarized in
the following table. In the table, the symbols A and B
correspond respectively to the bolts 23A and 23B in Figure 3.
TABLE
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Depth 200 mm 300 mm 400 mm
_ .. ~ .
Spec. A B A B A B
_ _ _
1 11,800(a) 7,100(a) 13,400(a) 12,800(b) 16,000(c) 17,500(c)
2 11,500(a) 6,900(a) 13,800(b) 12,100(b) 15,700(c) 17,800(c)
3 11,500(a) 7,000(a) 13,500(b) 12,500(b) 15,500(c) 16,900(c)
4 12,000(b) 7,200(a) 13,500(b) 13,000(b) 15,800(c) 19,800(c)
11,800(b) 7,000(a) 14,000(c) 12,500(b) 16,000(c) 19,500(c)
6 11,500(a) 6,900(a) 14,000(b) 12,500(b) 15,000(c) 20,300(c)
15 The n~ ,merical values in the table r ~epresent breaking loads in
killograms and the symbols (a), (b) and (c) represent the break-
ing conditions or states, ~herein (a) corresponds -to peeling
off between the foundation and filling material, (b) corresponds
to breakage of concrete and (c) corresponds to breakage of bolt.
The above result shows very small dispersion of the
measured values of three specimens and ensures reliability of
the method. It also shows -that a sufficient s-trength can be
obtained above 400 millimeters in depth and above 72 hours curing
time in this example. It has been confirmed that depth more
than 1,000 millimeters and curing time more -than one week are
required for obtaining the similar result and that the disper-
sion of the measured values is much greater and lower reli-
ability is anticipated, when conventional mortar is used as the
filling material.
Gravel, sand and crushed stone were tested as substitutes
for the ceramic balls in the resin composition. ~owever, the
results showed much inferiority as compared with the ceramic
balls in both mean value and dispersion of the measured ten-
sile strengths. Moreover, it was found that the use of these
filling materials made it difficult to move the bolt for posi-
tion correction and also interfered with the expelling of air
bubbles.
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~076~Z4
Glass balls and steel balls substituted for the ceramic
balls showed a little inferior results. This is believed to
be due to smoothness of the ball surfaces. Among many kinds
of balls which were tested, alumina ceramic balls which were
S non-glazed and commercially available for use in a ball mill
were found to be preferable.
In the above examples, bisphenol A epoxy resin having
viscosity of about 185 centipoises at 20C was used together
with hardener. However, it should be self-eviden-t to those
skilled in the art that other moldable resins such as poly-
ester resin, phenol-formaldehide resin, melamine resin, poly-
vinyl chloride resin and polyvinylidene resin, which exhibit
minimum volumetric shrinkage, are also useful.
It has been found that the tensile strength tends to
lS increase with reduction of ball size, that is, with increase
in packing density of the balls. However, -the packing density
is limited in practice because it becomes difficult to drive
the viscous resin composition into small cavities between the
balls. Repeated tests have showed that the gap between the
bolt and the hole wall should preferably be at leastl.S times
the ball diameter. This suggests that the improved strength
obtained in accordance with the method of this invention has
come from frictional resistance between the balls and, there-
fore, that it is desired to establish a hexagonal close-packed
structure throughout the balls in order to obtain maximum
strength. For completeness of this structure, it is desired
that the balls be as uniform in diameter as possible and that
each ball be ideally spherical. Compressive strength of the
ball should be large enough to overcome the tensile load, that
is, at least greater than that of the foundation material.
Although the method of this invention was described above ~ ;
in conjunction with certain embodiments, it should be noted
that various modifications and changes can be made without
departing from the scope of the invention. For example, this
method can be applied also to other foundations such as wood
and stone in addition to the aforementioned concrete and base
rock.
