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Description  |
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REFERENCE TO PATENTS, APPLICATIONS AND PUBLICATIONS PERTINENT TO THE
INVENTION
As far as we know, the prior document pertinent to the present invention is
Japanese Patent Publication No. 962/74 dated Jan. 10, 1974 which matured
into Japanese Pat. No. 743,738, corresponding to West-German Pat.
application No. P1708549.3 dated Jan. 22, 1968. The prior art disclosed in
said document will be described in the "Background of the Invention" given
herebelow.
FIELD OF THE INVENTION
The present invention relates to an earthquake-proof foundation structure
for a horizontal type coke oven battery.
BACKGROUND OF THE INVENTION
A conventional horizontal type coke oven battery for manufacturing
metallurgical coke comprises a plurality of coking ovens for carbonizing
coal charge, a plurality of combustion chambers for burning fuel gas, a
regenerator for storing remaining heat of the combustion waste gas from
the combustion chambers, and a sole flue for directing the combustion
waste gas after heat exchange in the regenerator to a stack. Said
plurality of coking chambers and combustion chambers are alternately
arranged in the horizontal direction on the regenerator. Each of the
combustion chambers comprises a plurality of heating flues, where fuel gas
is burnt to heat and carbonize coal charge in the coking ovens on the both
sides of the coking chamber through the oven walls, and thus to
manufacture coke. The sole flue is installed outside and below the
regenerator on the both longitudinal sides thereof, or directly below the
regenerator. above described structure is a very large-scale structure
easily subjected to damage, built by piling up a large number of bricks.
The foundation structure for such a coke oven battery should therefore, in
the occurrence of earthquake, not only be capable of largely reducing the
input acceleration of a seismic wave transmitted to the coke oven battery
to minimize the maximum relative displacement, the residual displacement
and the acceleration produced in the coke oven battery, but also permit
smooth release of expansion and contraction moments of the coke oven
battery under the effect of heat, thereby preventing damage to the coke
oven battery caused by the input acceleration of a seismic wave and/or
expansion and contraction under the effect of temperature change.
With this requirement in view, several earthquake-proof foundation
structure for a horizontal type coke oven battery have been proposed. For
example, Japanese Patent Publication No. 962/74 dated Jan. 10, 1974, which
matured into Japanese Pat. No. 743,738, corresponding to West-German
patent application No. P1708549.3 dated Jan. 22, 1968 discloses an
earthquake-proof foundation structure for a horizontal type coke oven
battery having a sole flue outside and below the regenerator on the both
longitudinal sides, which comprises:
a base plate; a supporting plate for mounting thereon said horizontal type
coke oven battery; a plurality of columnar supports arranged substantially
in a vertical position in the space between said base plate and said
supporting plate; a buffer for absorbing the input acceleration of a
seismic wave in the longitudinal direction of the coke oven battery,
provided near the middle of the longitudinal center line of said space
(hereinafter referred to as the "longitudinal buffer"); and buffers for
absorbing the input acceleration of a seismic wave in the transverse
direction of the coke oven battery, provided in two sets each within the
ranges of 1/4 from the both ends of said longitudinal center line
(hereinafter referred to as the "transverse buffer"); said supporting
plate being supported on said base plate by means of said plurality of
supports; said horizontal type coke oven battery being mounted on said
supporting plate; each of said plurality of supports being connected
substantially in a vertical position to said supporting plate and said
base plate, movably in any direction through a bearing at the head portion
and the leg portion thereof; each of said longitudinal buffer and said
transverse buffers comprising two opposite projections fixed to the upper
surface of said base plate and a projection fixed to the lower surface of
said supporting plate, said projection fixed to the lower surface of said
supporting plate projecting into the space between said two projections
fixed to the upper surface of said base plate, and an elastic body being
provided in each of the gaps between said two projections fixed to the
upper surface of said base plate and said projection fixed to the lower
surface of said supporting plate.
In the earthquake-proof foundation structure having the aforementioned
structure, the input acceleration of a seismic wave in all directions
transmitted from the ground to the base plate is absorbed by the
longitudinal buffer and/or the transverse buffers. It is therefore
possible to largely reduce the input acceleration of a seismic wave
transmitted to the coke oven battery mounted on the supporting plate and
hence to prevent damage to the coke oven battery caused by an earthquake.
The horizontal transverse force applied to the coke oven battery by a
pusher is abosrbed by the transverse buffers. Furthermore, since the
difference in expansion and contraction caused by a change in temperature
between the base plate and the supporting plate is absorbed by the
plurality of supports movable in all directions, no bending moment is
produced between the base plate and the supporting plate.
In the above-mentioned earthquake-proof foundation structure, however, each
of the plurality of supports is connected substantially in a vertical
position to the supporting plate and the base plate, movably in all
directions through a bearing at the head portion and the leg portion
thereof. Therefore, when the input acceleration of a seismic wave produces
a considerable relative displacement between the base plate and the
supporting plate, and as a result, said pluraity of supports largely
incline, there is a serious fear that said plurality of supports having
thus inclined may not be able to withstand the load of the coke oven
battery mounted on the supporting plate. The coke oven battery is mounted
directly on the supporting plate without no sliding layer in between.
Therefore, even if no bending moment is produced between the base plate
and the supporting plate as mentioned above, a bending moment caused by a
change in temperature may be produced between the supporting plate and the
lower surface of the coke oven battery.
An earthquake-proof foundation structure for a horizontal type coke oven
battery having a sole flue directly below the regenerator, as shown in the
schematic transverse vertical section view given in FIG. 1 has been
proposed, which is the most pertinent to the present invention.
In FIG. 1, 1' are a plurality of foundation piles driven substantially
vertically into the ground; 2' is a pile plate comprising solid concrete,
rigidly connected substantially in a horizontal position to the tops of
said plurality of foundation piles 1'; 3' is a base plate comprising solid
concrete for mounting thereon a horizontal type coke oven battery
described later, said base plate 3' being placed substantially in a
horizontal position on said pile plate 2' through a sliding layer 6'; and
4' is a horizontal type coke oven battery comprising a regenerator 4a', a
plurality of coking ovens and combustion chambers 4b' alternately arranged
in the horizontal direction on said regenerator 4a', and a sole flue 5'
installed directly below said regenerator 4a'. Said coke oven battery 4'
is mounted on said base plate 3' through a sliding layer 7'. Each of the
sliding layers 6' and 7' is formed by tightly laying a plurality of about
1-mm thick steel sheets coated with graphite grease over the entire
surface thereof into two or three laminations. However, among the surfaces
of said plurality of steel sheets, those being in contact with the upper
surface of the pile plate 2', the lower surface of the base plate 3', the
upper surface of the base plate 3' and the lower surface of the bottom 5a'
of the sole flue 5' of the coke oven battery 4' are not coated with
graphite grease. Said plurality of steel sheets may have any dimensions,
and said plurality of steel sheets are tightly laid into two or three
laminations by bringing their end edges into butt contact so that there
may be neither gap nor overlap between their end edges. Incidentally, 17'
is a heat-insulation layer comprising refractory, which covers the upper
surface of the base plate 3'.
According to the earthquake-proof foundation structure shown in FIG. 1
comprising the foundation piles 1', the pile plate 2', the base plate 3'
and the sliding layers 6' and 7', the input acceleration of a seismic wave
transmitted to the coke oven battery 4' is reduced by the sliding layers
6' and 7', thus permitting prevention of a damage to the coke oven battery
4' caused by an earthquake. It is also possible, under the effect of the
sliding layer 7', to smoothly release expansion and contraction moments
caused by a change in temperature of the bottom 5a' of the sole flue 5' of
the coke oven battery 4'.
The theory regarding such an earthquake-proof effect of the foundation
structure shown in FIG. 1 is based on the following fundamental concept.
More specifically, the sliding layers 6' and 7' are considered to have a
frictional coefficient of 0.2 as the design value. Therefore, when the
input acceleration of a seismic wave is transmitted through the ground,
the foundation piles 1', the pile plate 2', the sliding layer 6', the base
plate 3' and the sliding layer 7' to the coke oven battery 4', the
acceleration produced in the coke oven battery 4' is not considered to
exceed 200 gal corresponding to the frictional coefficient of 0.2 as shown
in the following equation:
Gravitational acceleration "g"=980 cm/s.sup.2
g.times.0.2=980 cm/s.sup.2 .times.0.2=196 gal.apprxeq.200 gal
Therefore, in the case where the input acceleration of a seismic wave
transmitted to the pile plate 2' through the foundation pile 1 ' is up to
200 gal, there occurs no relative displacement among the pile plate 2',
the base plate 3' and the coke oven battery 4', these moving as an
integral body by the friction, and thus, no adverse effect of earthquake
exerts on the coke oven battery 4'. On the other hand, in the case where
the input acceleration of a seismic wave transmitted to the pile plate 2'
through the foundation pile 1' is over 200 gal, only the pile plate 2'
moves in a behavior corresponding to the seismic wave under the effect of
the sliding layers 6' and 7', and the base plate 3' and the coke oven
battery 4' are kept in the stationary state. In an earthquake of any
magnitude, therefore, it has been considered that no residual displacement
would be produced among the pile plate 2', the base plate 3' and the coke
oven battery 4'.
According to the aforementioned fundamental concept concerning the
earthquake-proof effect of the foundation structure shown in FIG. 1, if
the frictional coefficient of the sliding layers 6' and 7' is close to
zero, almost no input acceleration of a seismic wave would be transmitted
to the coke oven battery 4', and in an earthquake of any magnitude, the
coke oven battery 4' would be kept in the ideal stationary state. We have
however noticed that there are the following serious doubts in the
conventional fundamental concept regarding the earthquake-proof effect
mentioned above:
(1) It is doubtful whether or not the graphite grease of the sliding layers
6' and 7' have actually a frictional coefficient of 0.2 just as designed;
(2) the frictional mechanism of the sliding layers 6' and 7' including
graphite grease is presumed to include not only a simple static friction,
but also a viscous friction;
(3) because the sliding layers 6' and 7' have no function to inhibit
inertia force produced in the coke oven battery 4' in an earthquake, the
coke oven battery 4' is placed in an unstable state at the time of
earthquake. Depending upon the magnitude of the earthquake, therefore,
considerable relative displacement and residual displacement may be
produced in the coke oven battery 4'.
SUMMARY OF THE INVENTION
A principal object of the present invention is therefore to provide an
earthquake-proof foundation structure for a horizontal type coke oven
battery, which is not only capable of largely reducing the input
acceleration of a seismic wave transmitted to the horizontal type coke
oven battery, thus considerably minimizing the maximum relative
displacement, the residual displacement and the acceleration produced in
said coke oven battery, but also capable of keeping said coke oven battery
in a stable state in an earthquake.
Another object of the present invention is to provide a foundation
structure for a horizontal type coke oven battery, which is capable of
smoothly releasing the expansion and contraction moments of the horizontal
type coke oven battery caused by heat.
In accordance with one of the features of the present invention, there is
provided an earthquake-proof foundation structure for a horizontal type
coke oven battery, which comprises:
a plurality of foundation piles driven substantially vertically into the
ground;
a pile plate rigidly connected substantially in a horizontal position to
the tops of said plurality of foundation piles;
a base plate for mounting thereon a horizontal type coke oven battery, said
base plate being placed substantially in a horizontal position on said
pile plate, said coke oven battery comprising a regenerator, a plurality
of coking ovens and combustion chambers alternately arranged in the
horizontal direction on said regenerator, and a sole flue installed
directed below said regenerator; and
two sliding layers each arranged between said pile plate and said base
plate and between said base plate and said sole flue of said coke oven
battery, each of said two sliding layers being formed by tightly laying a
plurality of steel sheets coated with graphite grease over the entire
surface thereof into two or three laminations, among the surfaces of said
plurality of steel sheets, those being in contact with the upper surface
of said pile plate, the lower surface of said base plate, the upper
surface of said base plate and the lower surface of said sole flue of said
coke oven battery not being coated with graphite grease;
said foundation structure being characterized in that:
the lower surface of said sole flue of said coke oven battery or the upper
surface of said base plate is provided with a longitudinal ridge and a
plurality of transverse ridges, while the upper surface of said base plate
or the lower surface of said sole flue of said coke oven battery is
provided with a longitudinal groove and a plurality of transverse grooves
to engage with said longitudinal ridge and said plurality of transverse
ridges at locations corresponding to said ridges, thereby said coke oven
battery being mounted on said base plate in a state in which said
longitudinal ridge and said plurality of transverse ridges respectively
engage with said longitudinal groove and said plurality of transverse
grooves corresponding thereto; and
said pile plate and said base plate are connected to each other on the both
longitudinal sides thereof by a plurality of buffers each of which
comprises a bolt fixed with a plurality of reinforcing ribs at the lower
portion thereof and an elastic ring engaging with the upper portion of
said bolt.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic transverse vertical section view illustrating a
conventional earthquake-proof foundation structure for a horizontal type
coke oven battery;
FIG. 2 is a schematic transverse vertical section view illustrating an
embodiment of the earthquake-proof foundation structure for a horizontal
type coke oven battery of the present invention;
FIG. 3 is a schematic section view of FIG. 2 cut along the line A--A; and
FIG. 4 is an enlarged schematic vertical section view illustrating an
embodiment of the buffer employed in the earthquake-proof foundation
structure for a horizontal type coke oven battery of the present invention
.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With a view to clarifying the above-mentioned defects and doubts involved
in the conventional earthquake-proof foundation structures for a
horizontal type coke oven battery, we have conducted extensive studies
through a preliminary sliding test, a vibration test, a horizontal loading
test and an earthquake response simulation as described below.
(1) Preliminary sliding test:
With regard to a sliding layer comprising a steel sheet coated with
graphite grease, a vertical two-side sliding test and a horizontal
one-side sliding test were carried out with the use of a 10-ton loading
machine to measure the frictional coefficient of said sliding layer. Said
vertical two-side sliding test was carried out by substantially vertically
holding a steel sheet coated with graphite grease on the both surfaces,
applying a horizontal load to the both surfaces of said steel sheet, and
vertically moving said steel sheet. Said horizontal one-side sliding test
was conducted by substantially horizontally placing on a table a steel
sheet coated with graphite grease on only one surface with the surface
coated with graphite grease as the underside, applying a vertical load to
the upper surface not coated with graphite grease of said steel sheet, and
horizontally moving said steel sheet.
The results of measurement of the frictional coefficient of the sliding
layer in the above-mentioned preliminary sliding test are shown in Table
1.
TABLE 1
______________________________________
Frictional coefficient of sliding layer
Surface Surface Surface
Sliding pressure pressure pressure
speed 0.4 kg/cm.sup.2
0.8 kg/cm.sup.2
1.2 kg/cm.sup.2
______________________________________
0.25 mm/minute
0.024 0.015 0.008
1.0 mm/minute
0.025 0.018 0.010
2.5 mm/minute
0.040 0.026 0.022
______________________________________
It became evident from the results of measurement shown in Table 1 that the
frictional coefficient of a sliding layer comprising a steel sheet coated
with graphite grease decreases according as the surface pressure
increases, and increases according as the sliding speed increases, and
that the frictional coefficient of said sliding layer is considerably
smaller than the design value of 0.2 described above.
(2) Vibration test:
A steel sheet coated with graphite grease on only one surface was
substantially horizontally placed on the vibration table of a vibration
test equipment with the surface not coated with graphite grease as the
underside. A model coke oven battery weighing 650 kg was mounted on the
upper surface coated with graphite grease of said steel sheet. An input
with a maximum acceleration of 250 gal having the same wave form as that
in the earthquake having occurred in Hachinohe, Japan and that in El
Centro to the south of Los Angeles, U.S.A. was applied to said vibration
table by said vibration test equipment to measure the acceleration and the
residual displacement produced in said model coke oven battery.
The results of said measurement including a maximum acceleration produced
in said model coke oven battery of 170 gal and a residual displacement of
6 mm-9 mm indicated that the residual displacement of said model increases
according as the input acceleration increases.
(3) Horizontal loading test:
A model pile plate was substantially horizontally placed on the table of a
horizontal loading test equipment. A model base plate was placed on said
model pile plate through a sliding layer comprising two steel sheets with
graphite grease sandwitched in between. A loading pressure was applied
onto said model base plate as a substitute for a coke oven battery. While
changing said loading pressure, said model base plate was horizontally
moved by the hydraulic jack of said horizontal loading test equipment to
measure the frictional coefficient of said sliding layer for each of the
value of the loading pressure.
The results of measurement of the frictional coefficient of the sliding
layer in the above-mentioned horizontal loading test are given in Table 2.
TABLE 2
______________________________________
Loading pressure
1.6 t/m.sup.2
5.8 t/m.sup.2
10.0 t/m.sup.2
______________________________________
Average value of
frictional coef-
0.037 0.014 0.009
ficient of sliding
layer
______________________________________
The results of measurement shown in Table 2 revealed that the frictional
coefficient of the sliding layer comprising two steel sheets with graphite
grease sandwiched in between is considerably smaller than the
above-mentioned design value of 0.2. Also, these test results clearly
indicate, as considered in combination with the test results of (1) and
(2) above, that the frictional mechanism of said sliding layer shows the
behavior of viscosity rather than that of the static friction.
(4) Earthquake response simulation:
With regard to a conventional earthquake-proof foundation structure for a
horizontal type coke oven battery having two sliding layers each formed by
laying a plurality of steel sheets coated with graphite grease on the
entire surface thereof into two or three laminations, arranged
respectively between the pile plate and the base plate and between the
base plate and the horizontal type coke oven battery, an earthquake
response simulation calculation of the coke oven battery was performed on
the basis of the test results of (1) and (3) above, under the following
conditions:
(a) Weight of the coke oven battery: 35,000 tons;
(b) frictional coefficient of the sliding layers: 0.02;
(c) viscosity coefficient of the sliding layers:
at the beginning of sliding: 8 t/m.sup.2 /m/sec,
after sliding: 1 t/m.sup.2 /m/sec;
(d) maximum input acceleration of the seismic wave:
150 gal, 200 gal, and 250 gal; and
(e) wave form of the input seismic wave:
14 kinds of seismic waves including those corresponding to the earthquake
at El Centro to the south of Los Angeles, U.S.A. and at Taft to the north
of Los Angeles, U.S.A.
The results of the aforementioned simulation calculation are shown in Table
3.
TABLE 3
______________________________________
Produced in coke oven battery
Average
Average value
value
of maximum
of residual
Average Value
relative displace- of maximum
displacement
ment acceleration
______________________________________
150 gal 4.6 cm 2.6 cm 31 gal
Maximum
input
accelera-
200 gal 8.1 cm 4.9 cm 33 gal
tion
of seismic
wave 250 gal 12.0 cm 7.0 cm 34 gal
______________________________________
The results of simulation calculation given in Table 3 revealed that, in
the earthquake-proof foundation structure mentioned above, the maximum
acceleration produced in the coke oven battery is very small as compared
with the maximum input acceleration of the seismic wave, suggesting the
effectiveness of the earthquake-proof effect, whereas the maximum relative
displacement and the residual displacement produced in the coke oven
battery are considerably larger than the allowable limits including a
maximum relative displacement of about 3 cm and a residual displacement of
about 2 cm, suggesting a very unstable state of the coke oven battery in
an earthquake.
The present invention has been made on the basis of the results of the
tests and the simulation mentioned under (1) to (4) above, and the
earthquake-proof foundation structure for a horizontal type coke oven
battery of the present invention comprises:
a plurality of foundation piles driven substantially vertically into the
ground;
a pile plate rigidly connected substantially in a horizontal position to
the tops of said plurality of foundation piles;
a base plate for mounting thereon a horizontal type coke oven battery, said
base plate being placed substantially in a horizontal position on said
pile plate, said coke oven battery comprising a regenerator, a plurality
of coking ovens and combustion chambers alternately arranged in the
horizontal direction on said regenerator, and a sole flue installed
directly below said regenerator; and
two sliding layers each arranged between said pile plate and said base
plate and between said base plate and said sole flue of said coke oven
battery, each of said two sliding layers being formed by tightly laying a
plurality of steel sheets coated with graphite grease over the entire
surface thereof into two or three laminations, among the surfaces of said
plurality of steel sheets, those being in contact with the upper surface
of said pile plate, the lower surface of said base plate, the upper
surface of said base plate and the lower surface of said sole flue of said
coke oven battery not being coated with graphite grease;
said foundation structure being characterized in that;
the lower surface of said sole flue of said coke oven battery or the upper
surface of said base plate is provided with a longitudinal ridge and a
plurality of transverse ridges, while the upper surface of said base plate
or the lower surface of said sole flue of said coke oven battery is
provided with a longitudinal groove and a plurality of transverse grooves
to engage with said longitudinal ridge and said plurality of transverse
ridges at locations corresponding to said ridges, thereby said coke oven
battery being mounted on said base plate in a state in which said
longitudinal ridge and said plurality of transverse ridges respectively
engage with said longitudinal groove and said plurality of transverse
grooves corresponding thereto; and
said pile plate and said base plate are connected to each other on the both
longitudinal sides thereof by a plurality of buffers each of which
comprises a bolt fixed with a plurality of reinforcing ribs at the lower
portion thereof and an elastic ring engaging with the upper portion of
said bolt.
Now the earthquake-proof foundation structure for a horizontal type coke
oven battery of the present invention is described further in detail by
means of an example with reference to the drawings.
EXAMPLE
FIGS. 2 to 4 illustrate the foundation structure for a horizontal type coke
oven battery of the present invention. In FIGS. 2 to 4, 1 are plurality of
foundation piles driven substantially vertically into the ground; 2 is a
pile plate comprising solid concrete, rigidly connected substantially in a
horizontal position to the tops of said plurality of foundation piles 1; 3
is a base plate comprising solid concrete for mounting thereon a
horizontal type coke oven battery described later, said base plate 3 being
placed substantially in a horizontal position on said pile plate 2 through
a sliding layer 6; and 4 is a horizontal type coke oven battery comprising
a regenerator 4a, a plurality of coking ovens and combustion chambers 4b
alternately arranged in the horizontal direction on said regenerator 4a,
and a sole flue 5 installed directly below said regenerator 4a. Said coke
oven battery 4 is mounted on said base plate 3 through a sliding layer 7.
Each of the sliding layers 6 and 7 is formed by tightly laying a plurality
of about 1-mm thick steel sheets coated with graphite grease over the
entire surface thereof into two or three laminations. However, among the
surfaces of said plurality of steel sheets, those being in contact with
the upper surface of the pile plate 2, the lower surface of the base plate
3, the upper surface of the base plate 3 and the lower surface of the
bottom 5a of the sole flue 5 of the coke oven battery 4 are not coated
with graphite grease. Said plurality of steel sheets may have any
dimensions, and said plurality of steel sheets are tightly laid into two
or three laminations by bringing their end edges into butt contact so that
there may be neither gap nor overlap between their end edges.
Incidentally, 17 is a heat-insulation layer comprising refractory, which
covers the upper surface of the base plate 3.
The foundation pile 1, the pile plate 2, the base plate 3 and the sliding
layers 6 and 7, which are the basic components of the earthquake-proof
foundation structure of the present invention, and the horizontal type
coke oven battery 4 to be mounted on the base plate 3 are substantially
the same as the foundation pile 1', the pile plate 2', the base plate 3'
and the sliding layers 6' and 7', and the conventional horizontal type
coke oven battery 4' to be mounted on the base plate 3'.
One of the features of the present invention lies in that, as shown in
FIGS. 2 and 3, the lower surface of the bottom 5a of the sole flue 5 of
the coke oven battery 4 is provided with a longitudinal ridge 8
substantially at the center portion thereof, whereas the upper surface of
the base plate 3 is provided with a longitudinal groove 9 to engage with
said ridge 8 at the location corresponding to said longitudinal ridge 8
thereof. Furthermore, as shown in FIG. 3, the lower surface of the bottom
5a of the sole flue 5 of the coke oven battery 4 is provided with a
plurality of transverse ridges 8' substantially at equal intervals in
parallel to each other, whereas the upper surface of the base plate 3 is
provided with a plurality of transverse grooves (not shown) to engage with
said plurality of transverse ridges 8' at the locations corresponding to
said ridges 8' thereof. FIG. 3 illustrates an embodiment in which seven
transverse ridges 8' are provided. However, it is needless to mention that
the number of transverse ridges 8' is not limited to seven, but should be
decided from designing considerations depending upon the weight and the
dimensions of the coke oven battery to be mounted.
The above described sliding layers 7 are arranged in a bent form to match
with the shape of said longitudinal rige 8 and said plurality of
transverse ridges 8', hence with the shape of said longitudinal groove 9
and said plurality of transverse grooves. The coke oven battery 4 is
therefore mounted on the base plate 3 in a state in which said
longitudinal ridge 8 and said plurality of transverse ridges 8'
respectively engage with said longitudinal groove 9 and said plurality of
transverse grooves corresponding thereto through the sliding layer 7.
Another feature of the earthquake-proof foundation structure of the present
invention is that the pile plate 2 and the base plate 3 mentioned above
are connected to each other by a plurality of buffers. Each of said
plurality of buffers comprises a bolt fixed with a plurality of
reinforcing ribs at the lower portion thereof and an elastic rubber ring
engaging with the upper portion of said bolt as shown in FIGS. 2 and 4. In
FIGS. 2 and 4, 10 is a bolt; 11 are a plurality of reinforcing ribs fixed
by welding to the lower portion of the bolt 10; 12 is an elastic rubber
ring engaging with the upper portion of the bolt 10; 13 are a plurality of
fitting holes having a diameter which permits insertion of the rubber ring
12, pierced at prescribed intervals on the both longitudinal sides of the
base plate 3; 14 are a plurality of fitting recesses having a diameter
which permits insertion of the lower portion of the bolt 10 fixed with the
reinforcing ribs 11, provided on the upper surface of the pile plate 2 at
the locations corresponding to said fitting holes 13; and 15 are covers of
the fitting holes. The elastic body, which should preferably be a rubber
ring, is not necessarily limited to a rubber ring, but may be any elastic
ring with a prescribed spring constant.
As shown in FIGS. 2 and 4, each of the buffers of the present invention is
fitted to the pile plate 2 and the base plate 3 substantially in a
vertical position by inserting the plurality of reinforcing ribs 11 fixed
to the bolt 10 into the fitting recess 14 provided on the upper surface of
the pile plate 2 through the fitting hole 13 pierced in the base plate 3
and by inserting the rubber ring 12 into the fitting hole 13 to cause said
rubber ring 12 to engage with the upper portion of the bolt 10. Thus, the
pile plate 2 and the base plate 3 are connected to each other by the
plurality of buffers on the both sides in the longitudinal direction
thereof. Incidentally, holes are pierced in the sliding layer 6 at the
locations corresponding to the plurality of fitting holes 13.
As mentioned above, each of the buffers is inserted into the fitting hole
13 of the base plate 3 and the fitting recess 14 of the pile plate 2.
Therefore, when the bolt 10 of the buffer is bent or damaged, the bolt 10
can be easily replaced. However, the bolt 10 is never bent or damaged if
the bolt 10 has a diameter sufficient to withstand any horizontal force
which may be applied to the bolt 10. The lower portion of the bolt 10
fixed with the reinforced ribs may therefore be directly burried into the
upper surface of the pile plate 2, without providing the fitting recess 14
as mentioned above on the upper surface of the pile plate 2. In this case,
the lower portion of the bolt 10 fixed with the reinforcing ribs is
previously burried substantially vertically at prescribed intervals into
the upper surface of the pile plate 2 on the both side in the longitudinal
direction thereof, and the rubber ring 12 is inserted into the fitting
hole 13 pierced in the base plate 3 at the location corresponding to the
bolt 10, to cause said rubber ring 12 to engage with the upper portion of
the bolt 10.
With regard to the earthquake-proof foundation structure constructed as
above, an earthquake response simulation of the coke oven battery 4 was
carried out under the following conditions while changing the spring
constant of the elastic rubber ring 12:
(a) weight of the coke oven battery: 35,000 tons;
(b) spring constant of the rubber ring:
7,000 t/m, 14,000 t/m and 28,000 t/m;
(c) maximum input acceleration of the seismic wave:
200 gal; and
(d) wave form of the input seismic wave:
14 kinds of seismic waves including those corresponding to the earthquake
at El Centro to the south of Los Angeles, U.S.A. and at Taft to the north
of Los Angeles, U.S.A.
The results of the aforementioned simulation calculation are given in Table
4.
TABLE 4
______________________________________
Produced in coke oven battery
Average value
Spring of maximum Average value
Average value
constant of
relative of residual of maximum
rubber ring
displacement
displacement acceleration
______________________________________
7,000 t/m
5.2 cm 0.88 cm 37.7 gal
14,000 t/m
4.7 cm 0.67 cm 44.0 gal
28,000 t/m
4.2 cm 0.40 cm 58.0 gal
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As is clear from the comparison of the results given in Table 4 and the
results shown in Table 3 of the simulation calculation as to the case with
a maximum input acceleration of the seismic wave of 200 gal carried out on
a conventional earthquake-proof foundation structure, in the
earthquake-proof foundation structure of the present invention equipped
wit | | |
