Hydraulic and earth engineering – Foundation – Columnar structure
Reexamination Certificate
2000-01-11
2002-08-20
Shackelford, Heather (Department: 3673)
Hydraulic and earth engineering
Foundation
Columnar structure
C405S232000, C405S231000
Reexamination Certificate
active
06435777
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an underpinning reinforcing means for foundations in civil engineering projects and buildings.
BACKGROUND TO THE INVENTION
The underpinning strength of foundations in civil engineering projects and buildings is achieved by the peripheral base exerting a resistive force on the foundation when an external force is applied to the foundation. The present applicant has disclosed a foundation body and method of forming foundations, which increase underpinning strength in JP-A-5-40085.
In the disclosed method of forming foundations, as shown in
FIGS. 8 and 9
, a foundation body
1
disposes an additional reinforcing materials
3
comprised of bar steel in the periphery of a deep main foundation body
2
. The additional reinforcing materials
3
extends radially from the deep main foundation body
2
in a horizontal sloping direction and is disposed plurally in the axial direction at fixed intervals. Each body is fixed into the peripheral natural ground
4
.
The foundation body
1
is formed by the method outlined below. Firstly in order to form the main foundation body
2
, the natural ground
4
is excavated in a fixed diameter and fixed depth in the vertical direction. A liner plate
6
is used to protect the excavation surface
7
. Next the additional reinforcing materials
3
are fixed in the natural ground
4
from an opening portion
5
provided beforehand at a fixed position in the liner plate
6
in the order as shown in
FIGS. 10-14
. In other words, firstly boring into the natural ground
4
is performed from the opening portion
5
as shown in FIG.
10
. As shown in
FIG. 11
, a hollow tube
9
, for fixation of a tip and into which the additional reinforcing materials
3
is previously inserted, is inserted into a hole
8
. The additional reinforcing materials
3
are longer than the hole
8
and the tip is expanded in a tapered shape to form a wedge
10
. Furthermore the hollow tube
9
is constituted by a pipe body
11
and a fixing tube
12
which is freely attachable and detachable from the tip. The fixing tube
12
, as shown in
FIGS. 15 and 16
, has a tapered portion
13
having the internal diameter of which is expanded toward the tip and a plurality of slits
14
formed in the axial direction from the tapered portion
13
. After the additional reinforcing materials
3
and the hollow tube
9
are inserted, as shown in
FIG. 12
, an extraction force is applied to the additional reinforcing materials
3
while the presser tool
15
compresses the base side of the hollow tube
9
. The fixing tube
12
is drawn into the natural ground
4
by the wedge
10
of the additional reinforcing materials
3
compressively expanding the tapered portion
13
of the fixing tube
12
. Hence the additional reinforcing materials
3
cannot be detached. After this, as shown in
FIG. 13
, if a hardening agent
16
is poured while the pipe body
11
of the hollow tube
9
is cut and detached from the fixing tube
12
, the additional reinforcing materials
3
, as shown in
FIG. 14
, will leave a basal ends
17
which projects toward the center of the main foundation body
2
and will be fixed on all sides in the hole
8
. In this way, the additional reinforcing materials
3
is fixed radially in the base in the horizontal and oblique direction at various depths.
Next while avoiding the basal ends
17
of the additional reinforcing materials
3
which projects from the natural ground
4
, assembly of reinforcing rods of the main foundation body
2
is performed. After this, a fixed plate
18
is secured to basal ends
17
on the inner side of the reinforcing structure as shown in FIG.
17
and FIG.
18
. The fixed plate
18
is welded to the axial reinforcing rod
19
and a lateral reinforcing rod
20
and the head of the basal ends
17
is secured to the fixed plate
18
by a fixing nut
21
. As regards the additional reinforcing materials
3
which are disposed in an oblique direction in
FIG. 8
, a fixed metal element
18
A, triangular in cross section such as that shown in
FIG. 19
, may be used instead of the fixed plate
18
to fix the basal ends
17
. In this way, after securing the basal ends
17
of each additional reinforcing materials
3
to the reinforcing rods
19
and
20
, the foundation body
1
as shown in
FIGS. 8 and 9
can be formed by placing the concrete of the main foundation body
2
.
In a foundation body
1
formed in this way, the additional reinforcing materials
3
is strongly integrated with the natural ground
4
due to the adhesive force of the hardening agent
16
plugging the periphery and the securing force to the natural ground
4
as a result of the wedge
10
resisting detachment. Thus the base in the periphery of the additional reinforcing materials
3
is strengthened. On the other hand, the basal ends
17
is rigidly attached to the main foundation body
2
due to being fixed to the reinforcing rods
19
and
20
of the main foundation body
2
. As a result, the foundation body
1
functions as a single foundation containing a peripheral base
22
. The surface on which shear resistance s acts when an extraction force Fv acts on the main foundation body
2
is the imaginary underpinning surface
23
connecting the tip of each additional reinforcing materials
3
as shown in FIG.
20
. Hence the surface area on which shear resistance s acts is conspicuously expanded and the underpinning strength with respect to an extraction force is greatly increased.
Furthermore the underpinning structure with respect to a horizontal force Fh is strengthened as shown in FIG.
21
. In other words, the surface on which the passive earth pressure p
1
and the elastic base reactive force p
2
act is expanded to an imaginary support surface
24
of the semicircular cross section connecting the tips of each additional reinforcing materials
3
which are disposed in the left half of the main foundation body
2
in the figure. Thus since the base
22
is strengthened by the additional reinforcing materials
3
, the range of the layers of earth B which obtain the elastic base reactive force p
2
is expanded in the upward direction. The resistance a of the additional reinforcing materials
3
, which is disposed in the right middle half of the figure of the main foundation body
2
, acts as an underpinning force with respect to extraction forces. Therefore the foundation body
1
obtains an extremely strong underpinning force with respect to horizontal forces Fh.
However in this type conventional foundation body and method for forming foundations, since there is no accurate standard for the method of placement of the additional reinforcing materials
3
with respect to the foundation body
1
, in other words the extension of the additional reinforcing materials
3
, it is not always possible to obtain a sufficient application of the reinforcing underpinning due to the additional reinforcing materials
3
. In other words, in foundations such as those of high voltage electricity towers for example, underpinning forces with respect to extractive forces are more of a problem than compressive forces. However even if it is attempted to create reinforced underpinning forces which resist a detaching force on the foundation body
1
, it has not been possible to create an accurate method of placing the additional reinforcing materials
3
.
The present invention is proposed to solve the above problems and has the objective of providing a foundation body and method of disposing an additional reinforcing material in foundations with a reinforced base which obtains a reinforced underpinning force especially with respect to detaching loads.
DISCLOSURE OF THE INVENTION
The present invention provides a method of forming foundations with a reinforced base by boring into the earth from the excavation surface of the foundations. After a highly rigid additional reinforcing material is fixed into the bore, the base of the additional reinforcing material is fixed to the main foundation body and the main foundation body is formed. The resistan
Iijima Masayoshi
Sekino Hideo
Tanabe Shigeru
Yoshii Yukio
Lagman Frederick L.
Rabin & Berdo P.C.
Shackelford Heather
Tokyo Electric Power Company
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