Note: Descriptions are shown in the official language in which they were submitted.
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GROUND REFORMING METHOD WITH A HARDENING MATERIAL
MIXED AND INJECTED AT A SUPER HIGH PRESSURE
AND REFORMING DEVICE OF SAME
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a method
for reforming ground-condition by using an instantaneous
hardening type hardening material or a combination of a slow
hardening type hardening material and a high pressure air to
reform soft ground conditions and harden foundations of
building sites. More particularly, two components of the
instantaneous hardening type hardening material are injected
into the ground through a two fluid mixing nozzle at the same
occasion.
Further, the present invention relates to a device
for reforming ground-condition by using the two fluid mixing
nozzle.
2. Description of the Prior Art
Conventionally, various ground reforming methods
using a hardening material jet have been provided. In these
methods, high pressure and high speed jet injection has been
applied to only a slow hardening type hardening material, on
the other hand an instantaneous hardening type hardening
material has been injected under a low pressure approaching
ambient pressure. The high pressure injection has been
conducted at highest 200 kg f/cm2, and no injection
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device adapted for higher injection pressures has
yet been proposed.
The instantaneous hardening type hardening material
cannot be used for such high pressure injection type ground
reforming method because the instantaneous hardening type
hardening material is composed of two separated liquids which
should be mixed after injection. If these two liquids are
mixed prior to injection, the hardening material will be
wholly or partially hardened in an injection pump or pipe.
lo Therefore the high pressure injection method has employed the
slow hardening type hardening material which requires a long
period to achieve hardening. However, the slow hardening
type hardening material will sometimes cause problems owing
to its slow hardening speed. For example, if the injection
amount is increased, the slow hardening type hardening
material will flow backwards to leak out of the injection
pipe or the like. Special injection angles such as horizontal
injection or upward injection will remarkably cause such
problems and thus cannot employ the high pressure injection
method.
In the high pressure injection method, reaction
force will be generated at the injection nozzle as the
injection pressure is increased, and the reaction force will
be applied to an injection rod. Revolving motion of the
injection rod will be affected by the reaction force and as a
result the injection rod will result in serious trouble.
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BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention
to provide a ground reforming method which can overcome the
above described problems.
It is another object of the present invention to
provide a ground reforming method available for any type
hardening material.
It is a further object of the present invention to
provide a ground reforming method which employs an
instantaneous hardening type hardening material injected at a
super high pressure of at least 200 kg f/cm2 to reform soft
ground and harden foundations of building sites.
It is a further object of the present invention to
provide a ground reforming device adapted for the above
method.
To accomplish the above objects, the ground
reforming method according to the present invention comprises
a first step Of inserting an injection rod into ground to be
reformed, which injection rod includes a first conduit and a
second conduit surrounding the first conduit, and a first
injection nozzle communicating with the first conduit and a
second injection nozzle surrounding the first nozzle and
communicat ing with the second conduit; a second step of
individually feeding first and second components of an
instantaneous hardening type hardening material or a slow
hardening type hardening material and a high pressure air
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into the first and second conduits of the injection rod; and
a third step of injecting the first and second components or
the slow hardening type hardening material and the high
pressure air under a super high pressure through the first
and second nozzles to mix each other with moving back the
injection rod from the inserted portion with revolving.
According to another aspect of the present
invention, the ground reforming device comprises an injection
rod including a first conduit through which a first component
of an instantaneous hardening type hardening material or a
slow hardening type hardening material is fed and a second
conduit through which a second component of the instantaneous
hardening type hardening material or a high pressure air is
fed, the second conduit surrounding the first conduit; a
first injection means communicates with the first conduit,
which means includes a pair of first injection nozzles
oppositely arranged in a side wall of the injection rod near
its top; a second injection means communicates with the
second conduit, which second injection means includes a pair
of second injection nozzles surroundingly arranged around
the first injection nozzles; and a drive means for
supporting and driving the injection rod to revolve and move
reciprocally.
The first and second components of the instantaneous
hardening typ~ ~ardening material are respectively fed into
the first ~nd second conduits without mixing each other under
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a super high pressure. These components are injected through
the injection nozzles and suddenly mixed with each other to form a
hardening material jet. In the case of the combination of
the slow hardening type hardening material and the high
pressure air, the slow hardening type hardening material and
the high pressure air are also isolatedly fed into the first
and second conduits, and injected through the injection
nozzles to mix the hardening material jet and the air jet.
The hardening material jet is wrapped with the air bubbles
and forcibly transported to a wide range by dynamic rupture
effect generated when the bubbles are ruptured. The jet
injected from the opposite nozzles can absorb reaction force
generated by injection from the other side. As the injection
rod is revolving and moving back from the inserted position,
the ground surrounding the injection rod is reformed into a
cylindrical hardened layer.
Other and further objects of this invention will
become obvious upon an understanding of the illustrative
embodiment about to be described or will be indicated in the
appended claims, and various advantages not referred to
herein will occur to one skilled in the art upon employment
of the invention in practice.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic illustration showing one
example of working state where the injection rod is inserted
in ground;
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Figure 2 is a vertical cross sectional view showing
the top portion of the injection rod according to the present
invention; and
Figure 3 is a cross sectional view taken along the
line X - X in Figure 2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A preferred embodiment of the present invention will
be explained in conjunction with the accompanying drawings.
In Figure 1, the reference numeral 1 denotes an
injection rod which includes a first conduit 2a and a second
conduit 2b isolated from each other as shown in Figure 2. The
first conduit 2a is arranged in a core of the injection rod 1
and is surrounded by the second conduit 2b. The first conduit
2a communicates with center nozzles 3a and 4a which are
oppositely arranged in the side wall near the tip of the
injection rod 1 and extend radially with respect to the
longitudinal axis of the injection rod 1. As shown in Figure
3, the second conduit 2b communicates with surrounding
nozzles 3b and 4b whose annular openings surround
respectively the center nozzles 3a and 4a.
The injection rod 1 is supported by a drive unit 5
which revolves and reciprocally moves the injection rod 1. The
injection rod 1 is further connected to a first feeding pipe
6a and a second feeding pipe 6b through a swivel joint 6.
Component A of an instantaneous hardening type hardening
material is fed into the first conduit 2a from the first
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feeding pipe 6a, and component B of the instantaneous
hardening type hardening material is fed into the second
conduit 2b from the second feeding pipe 6b. Alternatively, a
slow hardening type hardening material per se is fed into the
first conduit 2a from the first feeding pipe 6a, and
compressed gas such as air is fed into the second conduit 2b
from the second feeding pipe 6b.
The first and second feeding pipes 6a and 6b are
connected to a compressor, not shown in the drawings, to
generate a super high pressure fluid such as the
instantaneous hardening type hardening material or gas. The
compressor includes a piston, a valve chamber, cylinder and a
pressure sensitive member for transmitting pressure from the
cylinder to the valve chamber. The pressure sensitive member
is composed of active oil having different specific gravity
than the instantaneous hardening type hardening material, and
an elastic film actuated by the active oil. The active oil
is moved in response to the reciprocal motion of the piston
so that the hardening material can be introduced into the
valve chamber and then discharged out of the chamber by the
high pressure. In this compressor the hardening material is
isolated from the piston through the pressure sensitive
member. Therefore the hardening material can be discharged
without energy loss caused by the friction between the piston
and the hardening material. The valve chamber is provided
with an inlet through which the hardening material is
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introduced into the chamber and an outlet through which the
hardening material is discharged to the feeding pipe. Each
of the inlet and the outletare provided with a valve box
whose valve seat is sectionally formed in a half spherical
recessed shape. The valve seat is further formed with a
plurality of orifices in its axial direction. The valve seat
receives a valve member formed in a spherical shape adapting
for the valve seat. The valve member is always urged toward
the valve seat by a spring. This valve mechanism employing
the spherical valve member can promote to increase the
discharging pressure.
The drive unit 5 is preferable to be designed so that the
drive angle for the injection rod 1 can be freely changed and
the drive unit 5 per se can be moved without an additional drive
mechanism.
The top of the injection rod 1 is provided with an
excavating member 7 and a lubricating unit 8 as shown in
Figure 2. The lubricating unit 8 will discharge lubricant to
assist the excavating work of the excavating member 7.
Operation of the ground reforming method according
to the present invention will be described. The injection
rod 1 while revolving and discharging the lubricant from the
lubricating unit 8 is moved towards ground M to be reformed.
As the top of the injection rod 1 reaches a predetermined
depth, the lubricating unit 8 closes to stop discharging.
The component A of the instantaneous hardening type hardening
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material (or the slow hardening type hardening material) is
fed at a super high pressure into the first conduit 2a and
the component B of the instantaneous hardening type hardening
material (or gas) is fed at a super high pressure into the
second conduit 2b. Both the components A and B are injected
outwardly from the injection nozzles 3a, 3b, 4a and 4b while
the injection rod 1 is moved back while revolving. According
to this revolving injection, the components A and B are
completely mixed and then an essentially cylindrical hard
layer S in the ground M has been generated.
Experiment in sand having N-value 15 to 20 resulted
in an excellent reforming effect; that is, the cylindrical
hard layer having a large diameter of 3m 70cm was obtained
under conditions; injection pressure of 400 kg f/cm2,
injection rate of 100 Q/min, revolving speed of 8 r.p.m., and
back-moving speed of 2cm/min.
As given explanation above, the ground reforming
device according to the present invention can inject the
instantaneous hardening type hardening material at a super
high pressure 200 kg f/cm2 or more. When the instantaneous
hardening type hardening material is composed of two
components, the two components can be sufficiently and
uniformly mixed immediately before application to the ground
without back-flowing or leakage. On the other hand, when
compressed gas such as air is injected from one injection
nozzle and the slow hardening type hardening material is
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injected from the other nozzle, bubbles are generated by
mixing the slow hardening type hardening liquid material and
compressed gas. The hardening material jet is wrapped with
the bubbles and forcibly transported to a wide range by
dynamic rupture effect generated when the bubbles are
ruptured. Thus greater area will be hardened into a high
density cylindrical hard layer by ruptured hardening
material. The cylindrical hard layer may be formed in any
configuration such as parallel arrangement or alignment as
required.
Although the invention has been described in its
preferred form with a certain degree of particularity, it is
understood that the present disclosure of the preferred form
has been changed in the details of construction and the
combination and arrangement of parts may be resorted to
without departing from the spirit and the scope of the
invention as hereinafter claimed. For example, one side of
the injection means 3 and 4 or the feeding pipes 6a and 6b
may be provided with a regulator valve to control injection
condition, or the compressor may be further provided with a
regulating means.
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