JP2003155727A - Concrete lift placing method and green cut device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a green cut device capable of performing green cutting even after concrete is hardened and provide a concrete lift placing method capable of performing green cutting and cleaning simultaneously. SOLUTION: This green cut device 1 is provided with a plurality of pipes 21a, 21b provided with nozzles 23a, 23b at their tips and has rotating rotary injection bodies 20a, 20b. The rotary injection bodies 20a, 20b are rotated by a hydraulic motor 11 through a gear reduction gear mechanism. The green cut device 1 is moved. High pressure washing water is introduced into the pipes 21a, 21b of the rotary injection bodies 20a, 20b through swivel joints 27a, 27b. The high pressure washing water is turned into high pressure jet water stream by the nozzles 23a, 23b, and it is sprayed on a concrete placed face to hit it in order to remove laitance. Laitance can be removed even if concrete is hardened by spotlike hitting of high pressure jet water stream, green cutting and cleaning can be performed immediately before placing concrete, work efficiency is improved, and flexibility in work schedule is increased without receiving restriction of timing of green cutting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete lift placing method for placing concrete in multiple stages for each lift (semi-lift) and a green cut used in the method in constructing a dam or a large structure. Regarding the device.

[0002]

2. Description of the Related Art In the construction of large-scale concrete structures such as concrete dams, concrete is lifted (1 lift is about 1.2 to 1.5 m and half lift is 1/2 of that).
It is placed every time. It is necessary to remove the weak layer mortar that covers the surface of the concrete and the leitance raised by breathing so that the concrete joints of each lift do not become a structural weak point. This work is usually done before the concrete has fully hardened and is usually called green cutting. This green cut is performed by manually pressing high pressure water (40 to 2
(00 kgf / cm ² ) is sprayed on the concrete surface to remove latance and weak layer mortar with high water-cement ratio.
An apparatus for performing this green cut by a machine rather than manually is known from Japanese Utility Model Publication No. 4-55074.

When the green cutting is carried out too early and the hardening of the concrete is not sufficient, there is a problem that the concrete is cut too deep by spraying high pressure water, and the concrete is hardened too late. In this case, there is a problem in that it is not possible to remove the leitance or mortar adhering to the concrete surface. Normal,
6 to 12 hours in summer and 1 in winter from concrete pouring
Concrete compressive strength of 10 to 5 after 2 to 24 hours
Carry out when it is about 0 kgf / cm ² .

Further, even if the green cut is performed, the relatance may occur again after a long time. Therefore, when the concrete of the next lift is placed on this concrete at the stage where the hardening of the placed concrete has progressed over time, the latance attached to the surface of the placed concrete, Cleaning work is performed to remove foreign matters and dirt, and the concrete for the next lift is placed.

[0005]

In the concrete lift placing method, concrete is placed in layers in units of one lift or a half lift, and the work of this placing cycle is roughly divided into "forms". It has a critical path of "setting → casting → green cut". And in the case of normal dam concrete, 3 days with a half lift,
One lift 5 days is the length of this placing cycle. In such a work cycle, the green cutting must be performed before the placed concrete has fully hardened. Therefore, it restricts the degree of freedom of work and causes a decrease in overall work efficiency.

Further, immediately before the next pouring, the concrete surface must be cleaned again. That is, it is necessary to perform cleaning to remove foreign substances such as latance generated after the green cutting is performed and earth and sand that have come in and adhered from the concrete surface. In this way, the same work of removing harmful foreign substances from the already placed concrete surface has to be performed twice, and the work efficiency is deteriorated and the work is also reduced. This leads to higher costs. Therefore, the present invention is intended to improve such problems of the conventional technology.

[0007]

According to the present invention, in a concrete lift placing method in which concrete is placed in layers in lift units, the present invention provides a green cutting operation step for removing a leitance adhering to a concrete surface. The process was performed just before the installation. Then, this green cutting work removes the leitance adhering to the concrete surface by jetting a point-like high-pressure jet water stream toward the concrete surface and striking it, while simultaneously cleaning the concrete surface. did. This improves work efficiency, gives flexibility to the timing of green cutting, and facilitates work schedules. In particular, the pressure of the high-pressure jet water flow was set to be at least twice as high as the compressive strength of the concrete for green cutting and cleaning.

Further, as a green cutting device for carrying out the concrete lift placing method, a plurality of jet nozzles rotatably supported by the base body and arranged downward in the peripheral portion of the rotary, and high-pressure washing water at the jet nozzles. , A swivel joint that connects the introduction pipe connected to a high-pressure pump provided outside and the conduit of the rotary injector, and the rotary injector is driven via a transmission mechanism. And a hydraulic motor that operates. Then, while the rotating jet body is being rotated, a high-pressure jet water stream is jetted from the jet nozzle toward the concrete surface to strike it, thereby removing the leitance from the concrete surface. Further, a plurality of rotary jets of the green cutting device are arranged on a line perpendicular to the running direction of the green cutting device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing a working state in which a green cutting device 1 for removing a leitance or a weak layer mortar used in a concrete lift placing method of the present invention is attached to a working machine 2. . FIG. 2 is a front view of the green cutting device 1 as viewed from the right side of FIG. This green cutting device 1 is a device that enables the green cutting work immediately before placing, and at the same time can also perform the cleaning. When the compressive strength after hardening of concrete is 200 kgf / cm ² or more. Also, it is possible to inject high-pressure cleaning water that can remove the leitance and the like.

Two rotary jets 20a and 20b are rotatably supported on the base 10 of the green cutting device 1. The rotary jets 20a, 20b are central shaft tubes 24a, 2 that are respectively the central axes of rotation and form the conduits through which the wash water passes.
4b is rotatably supported on the base 10, and the tubes 24a, 2
Four horizontal pipes 21a, 21b forming a pipe line extending in the horizontal direction by pipe joints 22a, 22b are connected to 4b at 90 degree intervals, and injection nozzles 23a, 23b are provided at the tips of the horizontal pipes 21a, 21b. Each is installed.

The central shaft tube 24 of the rotary injectors 20a, 20b
a and 24b are connected to swivel joints 27a and 27b, and a gear 25 is attached to the central shaft tubes 24a and 24b.
a and 25b are attached. Introducing pipes 29a and 29b are connected to the swivel joints 27a and 27b via pipe joints 28a and 28b, and the introducing pipes 29a and 29b are connected.
Is connected via a pipe joint 30 and an introduction pipe 31 to a hose connected to a high pressure pump provided outside.

A hydraulic motor 11 is arranged on the base 10, and a gear 12 is attached to the output shaft of the hydraulic motor 11. The gear 12 is rotated by means of intermediate gears 26a and 26b. , 20b gears 25a, 25b
Is meshing with. This gear train 12, 26a, 25a,
The gear train 12, 26b, 25b constitutes a reduction mechanism.

Further, a pair of hydraulic cylinders 14a and 14b are attached to the tip of the base 10, and casters 13a and 13b are provided on the piston rods of the hydraulic cylinders 14a and 14b, respectively. The amount of projection of the casters 13a, 13b is adjusted by the hydraulic cylinders 14a, 14b, and the distance between the injection nozzles 23a, 23b of the rotary injectors 20a, 20b and the concrete placing surface to be green cut is adjusted. A mounting portion 16 for mounting the green cutting device 1 on the work machine 2 is provided at a rear end portion of the base 10. Further, the base 10 is provided with columns 15 for waiting the green cutting device 1 for maintenance such as maintenance and inspection of the green cutting device 1.

FIG. 3 is an explanatory view for explaining a state in which the green cutting device 1 is waiting by the working machine 2 for maintenance. As shown by the broken line in FIG.
The tip of the column 15 is hung up by the tip of the arm of the working machine and rotated around the mounting portion 16 to facilitate the maintenance of the lower surface of the rotary injectors 20a, 20b of the green cut device 1.

The work machine 2 is composed of a hydraulic power source, a hydraulic excavator having a boom, an arm, and the like, and a backhoe. The work machine 2 and the green cutting device 1 are mounted via a mounting portion 16 and a mounting means 18, and a green The hydraulic motor 11 of the cutting device 1 is connected to the hydraulic power source of the work machine 2 via the hose 17.

When the hydraulic power source of the working machine 2 is driven and the hydraulic motor 11 is driven, the gear 12 and the intermediate gears 26a, 26 are
b, central axis tubes 24a, 24 of the rotary jets 20a, 20b
Gears 25a and 25b attached to b are decelerated to rotate rotary injectors 20a and 20b. on the other hand,
The high-pressure pump provided outside is driven, and the introducing pipe 31, the pipe joint 30, the introducing pipes 29a and 29b, and the pipe joint 2 via the hose.
High-pressure water is introduced into the rotary jets 20a, 20b via the 8a, 28b and the swivel joints 27a, 27b. This high-pressure water is the central axis tube 24 of the rotary jets 20a, 20b.
a, 24b, is guided to four horizontal pipes 21a, 21b via pipe joints 22a, 22b, and is jetted as a high-pressure jet water stream from jet nozzles 23a, 23b at the tips thereof.

The rotary jets 20a and 20b rotate, respectively, and are jetted as high-pressure jet water streams from four jet nozzles 23a and 23b provided at the tips of the rotary jets 20a and 20b, respectively. The surface is punctured by the high-pressure jet water flow from each of the injection nozzles 23a and 23b. Moreover, since each of the four injection nozzles 23a and 23b swivels,
The hitting point moves in an arc shape. Further, by moving the work machine 2, the green cutting device 1 connected to the work machine 2 also moves, and as a result, the eight jet nozzles 23a, 23b strike different locations with a high-pressure jet water stream. become. This high-pressure jet water stream locally hits the concrete pouring surface in a dotted manner, causing concentrated stress on the concrete pouring surface, and the laitance and mortar on the pouring surface are destroyed and removed. Become.

As the hydraulic pump for generating the high-pressure jet water flow, a pump capable of obtaining high water pressure is used, and the high-pressure pump is used so that the water pressure of the jet water flow becomes 2-3 times as high as the compressive strength of the hardened concrete. Even with concrete that has been hardened by such a point-like impact with a high-pressure jet water stream, it is possible to reliably remove laitance and the like.

When this green cutting device 1 is applied to a concrete lift placing method in which concrete is placed in layers in lift units, the green cutting work can be performed even after the concrete is hardened, so that the next layer of concrete is placed. A green cut can be made immediately before, and there is no need to perform a green cut after placing, and it is possible to perform a green cut at the same time as cleaning the placing surface immediately before placing. The work process can be shortened, and the green cut work time zone can be freely set. That is, from the conventional cycle of form → cleaning → concrete placement → green cut → form → → placement cycle, green cutting and cleaning are performed simultaneously → concrete placement → green cutting and cleaning → form → The driving cycle is good and the work efficiency is significantly improved.

Moreover, conventionally, after the concrete has been poured, the green cut has to be performed when the concrete has not hardened yet and has a certain range of compressive strength (40 to 50 kgf / cm ² ). It was regulated and there was no freedom. However, by using the green cutting device and the green cutting method of the present invention, it is possible to remove the latance and the mortar on the surface even when the concrete is hardened. Therefore, the working process can be freely assembled. Further, since the green cutting is performed after the concrete is hardened, the generation of muddy water is small and the treatment cost can be reduced.

[0021]

Example: Compressive strength after hardening of concrete is 200 kg
At f / cm ² or more, it is possible to remove the leitance and to process a large area such as the planar construction method in which concrete is laminated in a planar shape represented by the RCD construction method and placed. In order to generate a high-pressure jet water flow, the high-pressure plunger pump 600 kg
f / cm ² was used.

Concrete compressive strength of 200 kg
Assuming f / cm ² , the rotational diameter (distance between collinear injection nozzles) of the rotary injectors 20a and 20b is 750 mm (the working width is 1. because two rotary injectors are arranged in parallel).
5m), the water pressure of the high-pressure jet water flow is 500kgf
/ Cm ² , the rotational speed of the rotary jet 2020 is 500 rpm
The pulling speed of the green cutting device 1 by the work machine 2 is set to 5
The green was cut and cleaned on the concrete pouring surface at m / min. In this case, the working efficiency is "0.7", it is possible to obtain a working efficiency of ^{60min × 5m / min × 1.5m =} 450m 2 / h 450m 2 /h×0.7=315m 2 / h, The work time is less than half compared to the case where the conventional green cut and cleaning are performed separately, and the cost (labor cost) required for this work is simply the operation of the working machine, so it is less than half the cost. I'm done.

Further, since the green cutting and the cleaning are performed at the same time before placing the concrete, the pressure of the jet water flow and the pulling speed of the working machine are adjusted according to the compressive strength of the concrete during the green cutting. For example, in the case of normal dam concrete, the placing cycle is on the third lift half day and the first lift fifth day. In this case, the concrete strength of the placing surface immediately before placing the concrete of the next layer is about 100 kgf / cm ² . In this case, the pressure of the jet water flow is 200 to 300 kgf /
Although it may be lowered to about cm ^{2, the} traction speed by the work machine may be increased to shorten the hitting time by the jet water jet applied to the concrete placing surface. If the concrete strength is about 100 kgf / cm ² , the pressure of the jet water jet may be set to 500 kgf / cm ² and the traction speed may be doubled to 10 m / min. If the concrete strength is lower, the pulling speed may be further increased. The maximum is about 15 m / min.

That is, the pressure of the jet water jet is adjusted or the traction speed of the working machine 2, which is the running speed of the green cutting device 1, is adjusted according to the concrete compressive strength of the placing surface immediately before placing the concrete, Make sure that the driving surface can be green cut.

It is also possible to use the green cutting device 1 to perform green cutting after the concrete has been cast in the same manner as in the conventional case, in a state where the concrete is not hardened. In this case, adjust the pressure of the jet water jet,
Try to jet at low pressure.

[0026]

According to the present invention, the green cutting is performed immediately before the concrete is set, and the surface of the concrete is also cleaned by this green cutting work. Therefore, the conventional green cutting process and the cleaning process are performed. Since the work that has been performed separately can be performed only once, the work efficiency is improved, and it is possible to perform the low-cost concrete piling.

Further, since the green cutting can be performed in a state where the concrete is hardened, the green cutting must be performed within a predetermined time after the concrete is placed. There is no limitation on the timing of performing the green cutting, and the flexibility of the work schedule is widened. You can set up an optimal work schedule. Further, since the green cut is performed after the concrete is hardened, less turbid water is generated, and the work can be performed efficiently and the processing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic view showing a work state in which a green cutting device according to an embodiment of the present invention is attached to a work machine.

FIG. 2 is a front view of the same embodiment.

FIG. 3 is an explanatory diagram illustrating a state when performing maintenance of the same embodiment.

[Explanation of symbols]

1 Green cut device 2 working machines 10 bases 11 Hydraulic motor 12 gears 13a, 13b casters 14a, 14b hydraulic cylinder 20a, 20b rotary injector 23a, 23b injection nozzle 25a, 25b gears 26a, 26b Intermediate gear 27a, 27b Swivel joint 22a, 22b, 28a, 28b, 30 Pipe joint 24a, 24b central axis tube 29a, 29b Introduction tube

Claims (4)

[Claims] 1. In a concrete lift placing method in which concrete is placed in layers in lift units, the green cutting work step for removing the leitance adhering to the concrete surface is a step just before placing the concrete, In the green cutting work, the point-like high-pressure jet water stream was jetted toward the concrete surface to strike it, thereby removing the leitance adhering to the concrete surface and at the same time cleaning the concrete surface. Characteristic concrete lift placing method. 2. The concrete lift placing method according to claim 1, wherein the pressure of the high-pressure jet water flow is at least twice as high as the compressive strength of the concrete to be green cut and cleaned. 3. A rotary jet body having a plurality of jet nozzles which are rotatably supported by a base body and are arranged downward in a peripheral portion of the rotary body, and a rotary jet body having a conduit for guiding high-pressure washing water to the jet nozzles. A swivel joint that connects the introduction pipe connected to the high-pressure pump and the conduit of the rotary injector, and a hydraulic motor that drives the rotary injector via a transmission mechanism, and rotate the rotary injector. A green-cutting device for removing laitance from the concrete surface by jetting a high-pressure jet water stream from the jet nozzle toward the concrete surface while striking it. 4. A green cutting device in which a plurality of the rotary jets are arranged on a line perpendicular to a running direction of the green cutting device.