JP2000189852A - Spraying nozzle and spraying method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the rebound ratio of sprayed cement concrete and fiber. SOLUTION: This spraying nozzle 1 comprises an inner pipe 10 attached to the end part of a pneumatic spraying hose 2 and an outer pipe concentric with the inner pipe 10 for spraying a pneumatic air. The inner pipe 10 is a tubular body made of a metal. The rear end 10b is attached to the pneumatic spraying hose 2. The outer pipe 20 is a tubular body. An air introduction pipe 23 is opened in the closed wall 22 of the outer pipe 20 and a pneumatically air sending flexible hose 24 is connected to the air introduction pipe 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spraying nozzle for use in a spraying method of a spray material, in particular, a cement concrete. In the present invention, paste, mortar, and concrete are collectively referred to as cement concrete.

[0002]

2. Description of the Related Art Conventionally, after excavating a tunnel, cement concrete is sprayed immediately after excavation in order to stop collapse of the ground and displacement of the ground. When sprayed cement concrete is sprayed on the ground, etc., a phenomenon occurs in which part of the sprayed cement concrete rebounds without adhering to the ground (hereinafter referred to as rebound), and the sprayed cement concrete falls down from the nozzle tip. There was a problem that. Furthermore, since dust is generated, a dust mask must be worn, and there is a problem that workability is deteriorated.

When the sprayed cement concrete is sprayed, the concrete rebound rate of the sprayed cement concrete expressed by (amount of the sprayed cement concrete that bounces down) / (amount of the sprayed cement concrete used for the spraying) × 100 (%) Is 20 to 40%, usually about 30%.

[0004] In order to increase the reinforcing effect, a sprayed cement concrete containing fibers whose length is as long as about 30 mm is used.

[0005]

However, if the length of the fiber is long, it is difficult to adhere to the ground or the like, and the amount of the fiber in the quick-set spray-cast cement concrete used for spraying / (amount of fiber which bounces and falls) / (spray). The fiber rebound rate represented by (amount) × 100 (%) is as large as about 40 to 50%, and in particular, in the case of high-strength sprayed cement concrete having a low water-cement ratio, it may be as large as 50 to 60%. If they do not adhere sufficiently, there is a problem that improvement in cracking resistance and bending strength cannot be expected.

[0006] As a method of reducing the amount of dust of the sprayed cement concrete, a space is provided between an inner pipe attached to an end of a spraying material pressurizing hose and an outer surface of the inner pipe, and a tip is formed inside. There has been proposed a method of using a nozzle constituted by an outer tube which is flush with the tip of the tube (Japanese Patent Laid-Open No. Hei 8-309245).

[0007]

However, even with these methods, there is a problem that the rebound rate and the amount of dust cannot be reduced, and the dripping from the nozzle tip cannot be eliminated.

As a result of intensive studies, the inventor has obtained knowledge that can solve the above-mentioned problems, and has completed the present invention.

[0009]

That is, the present invention provides an inner tube attached to an end of a spraying hose for spraying a sprayed material and ejecting the sprayed material, and concentric with the inner tube. A spray nozzle comprising an outer pipe for injecting compressed air, wherein a tip of the outer pipe is located forward of a tip of the inner pipe, and a tip of the outer pipe is closer than a tip of the inner pipe. The spray nozzle is characterized by being located at least 3 mm in front of the spray nozzle, wherein the spray nozzle is characterized in that the inner pipe is tapered so that the diameter of the inner pipe decreases toward the distal end. The spraying method is characterized in that the spraying material is sprayed using the spraying nozzle, and the blowing air pressure is 0.05 to 1 Mpa.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below in more detail with reference to the drawings.

The spray nozzle 1 according to the present invention is a tubular body as shown in FIG. 1, and has a rear end attached to a spray pressure hose 2 and sprays the spray material from inside the spray pressure hose 2 from the tip. It sprays.

As shown in FIG. 1, the spray nozzle 1 has an inner pipe 10 attached to an end of a spray pressure feeding hose 2.
And an outer tube 20 which is concentric with the inner tube and whose front end is located forward of the front end of the inner tube.

The inner tube 10 is a tubular body. The end attached to the blowing pressure feeding hose 2 is referred to as a rear end 10b, and the end for spraying the blowing material is referred to as a front end 10a. The rear end 10b is fastened to the spraying pressure feeding hose 2 by, for example, hose coupling.

The inner pipe 10 is preferably tapered so that the diameter of the inner pipe 10 is reduced toward the tip 10a in that the sprayed cement concrete can be prevented from scattering.

The blowing hose 2 having flexibility is an existing one.

The outer tube 20 is a tubular body concentrically located outside the inner tube 10. The rear end 20b of the outer tube is on the rear end 10b side of the inner tube 10, and the front end 20a of the outer tube is the front end 10a of the inner tube 10.
It is attached to the inner tube 10 so as to be located on the side.
In the attached state, the distal end 20a side of the outer tube 20 is located forward of the distal end 10a side of the inner tube 10.
The inner diameter of the outer tube 20 is larger than the outer diameter of the inner tube 10, and a cylindrical gap 21 between the inner surface of the outer tube 20 and the outer surface of the inner tube 10 when attached to the inner tube 10. Are formed.

On the rear end 20b side of the outer tube 20, for example, an annular sealing wall 22 is formed. The inner peripheral surface of the sealing wall 22 is fixed to the outer peripheral surface of the inner tube 10 by welding or the like. Therefore, the rear end 20b of the outer tube 20 is in a sealed state.

When the inner tube 10 is tapered so as to decrease in diameter toward the tip 10a, the outer tube 20 is also tapered.
The taper is provided so that the diameter decreases toward the distal end 20a so as to be concentric with zero.

One air inlet pipe 23 penetrating through the sealing wall 22 is formed in the sealing wall 22 of the outer tube 20. This air introduction pipe 23 has a flexible air pressure feeding hose 2.
4 are connected.

The length x of the inner tube 10 is 30 to 120 cm.
Is preferred, and 50 to 100 cm is more preferred.

The fixing position of the sealing wall 22 of the outer tube 20 is usually preferably near the center of the inner tube 10. When the fixing position is close to the tip 10 a of the inner tube 10, the compressed air is uniformly distributed over the entire outer periphery of the inner tube 10. It is more preferable that the inner tube 10 is fixed at least 50 mm rearward from the distal end 10a of the inner tube 10 because the inner tube 10 may not be pressure-fed.

The material of the inner tube 10 and the outer tube 20 of the spray nozzle 1 is preferably made of metal from the viewpoint of weldability.

When spraying cement concrete is used as the spraying material of the present invention, the design conditions of the spraying nozzle 1 are preferably as follows.

When the sprayed cement concrete is used as the spraying material, the inner diameter a of the tip 20a of the inner pipe is 6
0 to 80 mm is preferred. When the spray amount is small, the inner diameter a may be set to 60 mm or less. In this case, the difference between the inner diameter b of the rear end 10b of the inner pipe 10 and the inner diameter a of the front end 20a of the outer pipe 20 is as follows. 1-20 mm is preferred.

When the inner pipe is tapered, the rear end 10 of the inner pipe is used.
b and the inner diameter a of the inner tube tip 10a are 1
-30 mm is preferable, and 5-25 mm is more preferable.
If it is less than 1 mm, the rebound rate and the amount of dust may increase, and if it exceeds 30 mm, the inner tube 10 may be blocked.

The tip 20a of the inner tube 20 and the tip 1 of the inner tube 10
0a, the outer tube protrusion length c is 0.5 to 100.
mm is preferable and 3 to 50 mm is more preferable. 0.5
If it is less than mm, the rebound rate and the amount of dust may not be reduced, and if it exceeds 100 mm, the effect does not change, and the rebound rate and the amount of dust may not be reduced.

The size d of the gap 21 is 0.5 to 15 m
m is preferable, 1 to 10 mm is more preferable, and 2 to 7 m
m is most preferred. If it is less than 0.5 mm, the amount of compressed air to be pumped is small and the rebound rate and the amount of dust may not be reduced. If it exceeds 15 mm, the pressure of the compressed air may not be increased and the rebound rate and the amount of dust may not be reduced.

In the spraying method of the present invention, the spray pressure of the spray material is preferably 0.25 to 0.7 MPa.

The compressed air pressure blown into the gap portion 22 is set at 0.
It is preferably from 0.5 to 1 Mpa, more preferably from 0.1 to 0.7 Mpa. If it is less than 0.05 Mpa, the rebound rate may not be reduced, and if it exceeds 1 Mpa, the pressure of the compressed air may increase and the amount of dust may increase.

As the spraying material used in the present invention, it is preferable to use ordinary spraying cement concrete.

The sprayed cement concrete used in the present invention is prepared by mixing cement, water, and, if necessary, fine aggregate, coarse aggregate, fiber, silica fume, inorganic powder, and a water reducing agent. is there.

The amount of fiber used is preferably 0.1 to 1.5 parts by volume based on 100 parts by volume of sprayed cement concrete.
0.6-1.2 volume part is more preferable. If the amount is less than 0.1 part by volume, strength developability may be reduced. If the amount exceeds 1.5 part by volume, the rebound rate may be large, and the workability, the mixing and dispersibility, and the economic efficiency may be deteriorated.

The amount of water used is preferably from 35 to 65%, more preferably from 45 to 60%, in terms of water / cement ratio, from the viewpoint of strength development. If it is less than 35%, the cement concrete cannot be sufficiently mixed, and if it exceeds 65%, the strength development may be reduced.

The slump of the sprayed cement concrete thus prepared is preferably from 6 to 23.5 cm, more preferably from 10 to 21 cm.

Further, a quick setting material may be mixed with the sprayed cement concrete to be used as a quick setting sprayed concrete. In this case, the sprayed cement concrete is pumped under pressure, mixed with the quick-setting material immediately before spraying, and sprayed onto the ground as quick-setting sprayable concrete. or,
The quick setting material may be mixed into the compressed air.

The amount of the quick-setting material used is preferably 3 to 20 parts by weight, more preferably 5 to 15 parts by weight, based on 100 parts by weight of cement. If the amount is less than 3 parts by weight, the initial strength development property is small, and the sprayed cement concrete may be peeled off. If the amount exceeds 20 parts by weight, the pumping properties such as blockage in the spraying pressure hose 2 are reduced, and the rebound rate is large. And the long-term strength development may be reduced.

When spraying cement concrete is used as the spraying material of the present invention, the spraying material pumped inside the inner pipe 10 is pumped between the inner pipe 10 and the outer pipe 20 to make the gap 21
Rather than being sprayed by mixing with more injected compressed air,
The rebound rate and the amount of dust are greatly reduced.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given based on embodiments.

Experimental Example 1 The inner diameter a of the front end 20a of the inner tube was 50 mm, and the rear end of the inner tube was 10 mm.
b inner diameter b = 67 mm, outer tube protrusion length c = 10 mm,
The size d of the gap 21 is 3 mm, and the length of the inner tube x is 700 m.
The following spray test was carried out using a spray nozzle 1 in the form of a double pipe with m and outer pipe length = 250 mm. The pressure of the air was 0.3 Mpa, and the material of the spray nozzle 1 was made of metal. The outer tube was made concentric with the inner tube. Sprayed cement concrete having the composition shown in Table 1 was prepared using a sprayer “Aliber 280” manufactured by Alibr.
Pumped. Separately from this, the quick-set material is fed to 100 parts by weight of cement using the “NATOM CLEAT”.
Immediately before spraying, the quick-setting material and the sprayed cement concrete were mixed with a Y-shaped pipe to prepare a quick-setting sprayable concrete. 100 liters of the prepared quick-setting spray concrete were sprayed on the side wall of a 4.5 m wide 4.5 m high 5 m long tunnel simulating a horseshoe made of an iron plate. Table 2 shows the test results.

<Materials Used> Cement: Normal Portland cement, Blaine value 34
20cm ² / g, specific gravity 3.16, commercial product Fine aggregate: lime sand from Aomi, Niigata, specific gravity 2.64 Coarse aggregate: river gravel from Himekawa, Itoigawa, Niigata, specific gravity 2.65,
Maximum dimension 10mm Water: drinking water Fiber: steel fiber, length 30mm, specific gravity 7.8, commercial product Water reducing agent: high performance water reducing agent, polycarboxylic acid type, commercial product Quick setting material: calcium aluminate / gypsum = 1 / A mixture consisting of 1 (weight ratio). However, calcium aluminate corresponds to the C ₁₂ A ₇ composition, and is amorphous and has a Blaine value of 6.
Using those 050cm ² / g, plaster used was of type II anhydrous gypsum, Blaine 6050cm ² / g.

<Measurement method> Concrete rebound ratio: (Amount of quick-setting spray-cast cement concrete that bounces down) / (Quick-setting property used for spraying) when quick-setting spray concrete is sprayed on the side wall for 1 minute Amount of sprayed cement concrete) x 1
It was shown as 00 (%). Fiber rebound rate: The fiber rebound rate was indicated. (Amount of fibers bounced and dropped) / (Amount of fibers in quick-set sprayed cement concrete used for spraying) × 10 when quick-setting sprayable concrete is sprayed on the side wall for 1 minute
It was shown as 0 (%). In addition, the amount of fibers that bounced off
The fibers were sucked and collected by magnets from the rebounded quick-setting sprayed concrete, and the cement adhered to the steel fibers was washed off and dried, and then measured.

[0042]

[Table 1]

[0043]

[Table 2]

EXPERIMENTAL EXAMPLE 2 As a comparative example, the experiment was carried out in the same manner as in Experimental Example 1, except that a single tube spray nozzle having an inner diameter of 67 mm at the rear end of the nozzle, an inner diameter of 50 mm at the tip of the nozzle, and a nozzle length of 700 mm was used. Table 2 shows the results.

EXPERIMENTAL EXAMPLE 3 A spraying nozzle in which the difference between the inner diameter b of the rear end 10b of the inner pipe shown in Table 3 and the nozzle diameter a was changed as shown in Table 3 by changing the inner diameter a of the front end 20a of the inner pipe. Experimental example 1 except that
The same was done. Table 3 shows the results.

<Measurement method> Pumpability: The case where the quick-setting spray concrete does not adhere to the spray nozzle after spraying is indicated by "O". The case where pulsation occurred during the spraying of the cement concrete was rated as Δ, and the case where pulsation occurred during the quick-setting spraying of the cement concrete with adhesion of the quick-setting cement concrete was rated as ×.

[0047]

[Table 3]

Experimental Example 4 An experiment was performed in the same manner as in Experimental Example 1 except that the length of the outer tube was changed and a spray nozzle having an outer tube protrusion length c shown in Table 4 was used. Table 4 shows the results.

[0049]

[Table 4]

Experimental Example 5 An experiment was carried out in the same manner as in Example 1 except that the diameter of the outer tube tip was changed and a spray nozzle having a size d of the gap 21 shown in Table 5 was used. Table 5 shows the results.

[0051]

[Table 5]

Experimental Example 6 An experiment was performed in the same manner as in Experimental Example 1 except that the spray nozzle was used under the conditions of the compressed air pressure shown in Table 6. Table 6 shows the results.

<Measurement Method> Dust amount: Using a digital dust meter manufactured by Shibata Scientific Instruments Co., Ltd., the amount of dust was measured for 1 minute after the start of spraying at the center of the simulated tunnel, and the amount of dust per 1 m ³ was calculated.

[0054]

[Table 6]

[0055]

According to the spray nozzle of the present invention, not only the rebound rate of the sprayed cement concrete but also the rebound rate of the fiber can be drastically reduced. Furthermore, the initial and long-term strength and strength development properties are increased. By these effects, the bending strength and crack resistance of the cement concrete are improved. Furthermore, since expensive fibers can be used effectively, there is an advantage that economy can be improved and the amount of quick-setting material can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a spray nozzle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Blowing nozzle 2 ... Blowing pressure feeding hose 10 ... Inner tube 10a ... Tip of inner tube 10b ... Rear end of inner tube 20 ... Outer tube 20a ... Tip of outer tube 20b ... Rear end of inner tube 21 ... Gap 22 ... Sealing wall 23 ... Air introduction pipe 24 ... Air pressure feeding hose a ... Inner diameter of the tip of the inner pipe b ... Inner diameter of the rear end of the inner pipe c ... Projection length of the outer pipe d ... Size of the gap x ... Length of the inner pipe

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Isao Terashima 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Inside the Aomi Plant of Denki Kagaku Kogyo Co., Ltd. Chemical Industry Co., Ltd. Aomi Plant (72) Inventor Tsuyoshi Koide 2209 Aomi, Aomi-cho, Nishikubiki-gun, Niigata Prefecture F-term (reference) 2D055 DB02 LA10 4D075 AA02 CA50 DA23 DB70 DC50 EA14 EB03 EC22 4F033 AA00 CA04 FA00 QA01 QB02Y QB09X QB12Y QB20 QC02 QD04 QD20

Claims (5)

[Claims] 1. An inner pipe attached to an end of a spraying pressure feeding hose for feeding a spraying material and spraying the sprayed blowing material, and an outer pipe which is concentric with the inner pipe and injects compressed air. A tip of the outer tube is located forward of a tip of the inner tube. 2. The tip of the outer tube is 0.5 mm from the tip of the inner tube.
2. The spray nozzle according to claim 1, wherein the spray nozzle is located forward by at least 100 mm. 3. The spray nozzle according to claim 1, wherein the inner pipe is tapered so that the diameter of the inner pipe decreases toward the distal end. 4. A spraying method, wherein a spraying material is sprayed using the spraying nozzle according to claim 1. 5. The spraying method according to claim 4, wherein the compressed air pressure is 0.05 to 1 Mpa.