JP3253925B2 - Wet spraying method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet spraying method suitable for construction of tunnels and underground structures.

[0002]

2. Description of the Related Art In the construction work of tunnels, underground spaces, and the like, a method of spraying raw concrete on an exposed surface after excavation and lining the exposed surface to prevent the exposed surface from collapsing is widely used. As a construction method of spraying the raw concrete, a dry construction method and a wet construction method are known, but the wet construction method has an advantage that a smaller amount of dust is generated as compared with the dry construction method. It is the mainstream of the construction method.

[0003] The raw concrete used in the wet method (hereinafter referred to as "base concrete") is pumped through a transport pipe, sprayed from the spray nozzle at the tip to the exposed surface excavated, and lined. It is. In that case, the base concrete used is a "slump: 10 to 22 cm" having a relatively high viscosity in order to improve the adhesion at the time of spraying.

[0004] A highly fluid concrete having a slump of 22 cm or more and exhibiting fluidity at a slump flow value.
The sheet is not used as a base concrete. The reason is that when wet spraying is performed using a base concrete having high fluidity, in addition to a decrease in quick setting property and an increase in rebound, a part of the sprayed concrete is also dripped. This is because it was considered to be an impractical construction method and was not considered for the study because a significant decrease in the amount of adhesion due to falling was expected.

[0005] In the wet method, only the base concrete is not sprayed. Usually, in order to give quick-setting property, a quick-setting agent is added and mixed during pumping of the concrete. Concrete (hereinafter "spray concrete")
”).

[0006] Recently, the excavation work of tunnels and underpasses has become large-scale, and the excavated cross section and exposed surface have been increased, resulting in: ・ Amount of spraying per hour increased; ・ Improvement of spraying efficiency; Is increasing.
In addition, the increase in the exposed surface increases the frequency of exposure of rocks having extremely low strength and increases the risk of falling. Therefore, the development of a wet spray concrete exhibiting higher strength is desired. Furthermore, in the conventional spraying method, cracks and holes on the exposed surface are closed, and the flowing out groundwater is stopped.
(Hereinafter referred to as "water stopping performance") was insufficient, so that improvement in this respect was also expected.

[0007]

In such a situation, the conventional wet spraying method focuses on adhesion,
A hard base concrete having some stickiness is used. However, due to the stickiness, the amount of the base concrete pumped is limited, and the construction efficiency is reduced. Also, the base concrete being pumped and the quick setting agent added in the middle thereof (particularly, Inadequate mixing with the powder quick-setting admixture) results in inhomogeneous spray concrete, resulting in large variations in the strength of the sprayed concrete. Was.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and disadvantages, and has as its object to provide a wet spraying method for a large-scale tunnel construction or the like; , The amount of sprayed concrete (per hour) is increased, the quick-setting and adhesion of the sprayed concrete is maintained, and the water stopping performance is improved. It can reduce the rebound rate of the spray concrete and stabilize the quality of the spray concrete. Furthermore, when the base concrete is left at a high temperature for a long time, Another object of the present invention is to provide a wet spraying method capable of exhibiting these characteristics.

[0009]

The inventors of the present invention have conducted intensive studies to solve the problems and disadvantages of the prior art, and as a result, have found that a "slump flow" has been applied to a base concrete for wet spraying. With the idea of introducing the concept of the present invention, experiments were conducted, and it was confirmed that the above object could be achieved. Thus, the present invention described in detail below was completed.

That is, the construction method according to the present invention is described in
Tunnel, in the wet spraying installation to be applied to the construction of underground structures, the amount of hydraulic powder include 450～700Kg /
m ^3, coarse aggregate amount 0.20~0.24m ³ / m ^3, the fine aggregate ratio 55-6
5% by volume , base binder with a slump flow of 450 mm or more , 4-10% by weight of quick setting agent based on hydraulic powder
Addition and spraying "(claim 1) is the gist (items specifying the present invention).

The present invention is characterized in that: the slump flow is 450 to 750 mm;
2) The slump flow is 500 to 700 mm.
3) and · The time required for the base concrete to flow through the V-rotor is 5 to 2
0 seconds (claim 4).

Further, the present invention is base - Sukonkuri - in DOO, amount of-hydraulic powder is added the amount of 530~700kg / m ³ and Kyuyuizai 5 against water hydraulic powder weight 10 by weight% (claim 5), the maximum particle size of-aggregate is 15mm or less (claim 6), - the unit amount of water is 160~200kg / m ³ (claim 7),
And the ratio of water / hydraulic powder is 28 to 40% by weight (Claim 8 ).

Furthermore, the present invention is, Baie - Sukonkuri - DOO comprises retarder (claim 9), Baie - Sukonkuri - DOO comprises anhydrite (claim 1
0 ), and the base concrete contains fibers (claim 11 ).
It is characterized by the following.

[0014]

Embodiments of the present invention will be described below. The wet spraying method according to the present invention is characterized in that the base concrete to be used is limited to one having a specific fluidity, and the concept of "slump flow" is introduced as an index of the fluidity. is there.

First, the concept of the "slump flow" will be described. The concept of "slump flow" is a concept used to evaluate the fluidity of high-concrete concrete in the field of utilizing the concrete.

The high-fluid concrete is a concrete in which water is poured into every corner of the casting site like water, and the concrete is cast with a normal slump. Can not be represented. Therefore, in the field of the use of high-fluid concrete, attention was paid to the fact that the extent of the concrete in the "slump test" accurately indicates the fluidity. The concept of "-" has been introduced. This spread is called "slump flow", and the larger the spread, the higher the fluidity.

In the wet spraying method of the present invention, it is important to use a base concrete having high fluidity, and the above-mentioned concept of slump flow is adopted in order to appropriately express the fluidity. This method has never been attempted in the conventional spraying industry. (Note) Conventional spray base concrete (raw concrete)
The evaluation of the fluidity adopted in (g) shows the degree of deformation of the concrete cone in a numerical form, which is referred to as "slump".

The limitation of the slump flow of the present invention will be described. The present invention is characterized in that a high-flow base concrete having a slump flow of 450 mm or more is used, and the material must not cause material separation (see the measuring method of the slump flow described below). Furthermore, the high fluidity of the base concrete facilitates mixing of the after-mentioned hardening agent to be added, thereby contributing to the stabilization of the spray concrete, improving the adhesion and reducing the rebound rate. , Has the feature.

If the slump flow is less than 450 mm, the pumping performance will decrease, the rebound rate will increase, and
The amount of spray (unit time) decreases, which is not desirable (→
See Comparative Example 1 below). In addition, the adhesion tends to decrease, and the water stopping performance tends to decrease, which is not preferable.

The upper limit of the slump flow is preferably 750 mm. The reason is that the base concrete is preferable because the pumping amount can be increased as the slump flow becomes larger, but if it exceeds 750 mm, the rebound rate tends to become higher, and the addition of a quick setting agent The rate must be high. Further, depending on the pumping machine used, separation of the coarse aggregate and the mortar portion is liable to occur, which is not preferable because it may cause the transportation pipe to be blocked. A more preferred slump flow is 500 to 700 mm.

Next, the quick-setting agent used in combination with the base concrete will be described. The quick setting agent is based on the above base concrete.
The chemical component is added to impart quick-setting properties to the steel, and the chemical component is not particularly limited, but a cement-based one is preferable. For example, a combination of calcium aluminate with an alkali aluminate and / or an alkali carbonate, a combination of calcium aluminate or calcium sulfoaluminate with gypsum, and the like can be given. Commercial products including these can be used. The addition amount of the quick setting agent is preferably 4 to 10% by weight based on the hydraulic powder, taking into account the quick setting property, long-term strength, cost and the like.

Next, the viscosity of the base concrete will be described. The higher the fluidity of the base concrete, the better the pumpability, but the adhesive property is reduced, the water stopping performance is reduced, and material separation tends to occur easily. Therefore, in the present invention, the base concrete is provided with a certain degree of viscosity in order not to lower the performance.

The method of measuring the viscosity of the base concrete is as follows.
Although several methods are known, a test method using a "V-roth" is suitable for the measurement of a base material having a high fluidity such as the present invention, and was adopted. The test method using the "V-Roat" is described in "Appendix 1. High-flow concrete" described in "Guidelines for materials, preparation, manufacturing and construction of high-flow concrete (draft)" issued by the Architectural Institute of Japan. This method uses the "V-roth" specified in "Consistency Evaluation Test Method" and makes the sample (base concrete) flow down in viscosity.

The relationship between the viscosity and the flow time by the "V-rot" is such that the smaller the former, the shorter the time of the latter. Flow time (viscosity) in base concrete
And the other characteristics, for example, the smaller the former,
Although the pumping performance is improved, the adhesion is reduced, the water stopping performance is also reduced (clogging becomes insufficient), and the rebound rate tends to increase.

The time required for the base concrete to flow through the "V-rot" is preferably 5 to 20 seconds. If it is constructed using this range, the pumping property is good, the material does not separate, the pulsation does not occur, the adhesion of the spray concrete is good, the water stopping performance is improved, Moreover, it is preferable because the rebound rate is small. If the falling time is less than 5 seconds, the quick-setting property decreases, the rebound rate increases, the coarse aggregate and the mortar / paste parts tend to separate, and stable spraying is performed. It is not preferable because it is difficult. Conversely, if it exceeds 20 seconds, the viscosity of the base concrete is high,
In addition, the pumping performance is reduced, and the mixing of the quick-setting agent to be blown is insufficient, so that the quick-setting property of the sprayed concrete tends to decrease, and the variation in quality is unfavorably increased.

Next, preferred conditions for blending the base concrete for performing wet spraying will be described.
The compounding conditions include, for example, when spraying a large cross-section wall surface, etc., in addition to adhesion, rebound rate, spray amount, etc.
Sprayed concrete closes cracks, etc., and the compressive strength after curing is 50 N / mm ² or more (28 days old)
In particular, the amount of base concrete hydraulic powder, the maximum particle size of the aggregate,
The unit water volume and the water / hydraulic powder ratio are important. Less than,
The mixing conditions will be described.

First, the hydraulic powder and its compounding amount will be described. Hydraulic powders used for the production of base concrete include Portland cements such as ordinary and early strength, and limestone, quartzite, fly ash,
What mixed the powder admixtures, such as slag, is mentioned.
The fineness of the powder admixture is not particularly limited, but is preferably not less than 3,000 cm ² / g, and the mixing ratio is appropriately selected in consideration of the compressive strength and the like. Just do it.

The mixing amount of the hydraulic powder is 450 to 700 kg.
/ M ³ . When the blending amount is less than 450 kg / m ³ , it is difficult to adjust the slump flow of the base concrete to 450 mm or more, and there is a fear that the pumping property may be reduced, which is not preferable. On the other hand, when it exceeds 700 kg / m ³ , the fluidity of the base concrete is reduced, the viscosity is increased, and the pumping property may be reduced, which is not preferable.

In order to sufficiently shut off the groundwater that flows out by blocking cracks and holes on the exposed surface when excavating,
The effect of adhesion and quick setting is great. In particular, in the above-mentioned slump flow and viscosity range, the hydraulic powder is 530
-700 kg / m ³ , and if the quick-setting agent to be added to the base concrete is added in an amount of 5 to 10% by weight based on the amount of the hydraulic powder, adhesion and rapidity can be improved. Both the binding properties are good and the water stopping performance is improved, which is preferable.

Next, the aggregate will be described. Conventional coarse and fine aggregates can be used. For example, coarse aggregate includes river gravel, sea gravel, crushed stone and mixtures thereof, and fine aggregate includes river sand, sea sand, mountain sand, crushed sand and mixtures thereof.

In the present invention, it is preferable to use a coarse aggregate having a maximum particle size of 15 mm or less. When coarse aggregate exceeding 15 mm is used, material separation tends to occur, and the spray amount (per hour) tends to decrease. Further, the rebound (scattering) of the coarse aggregate at the time of spraying is increased so that not only the rebound rate is increased, but also a large amount of rebound post-treatment may cause a problem, which is not preferable.

[0032] In addition, the aggregate, the coarse aggregate amount 0.20~0.24m ³
/ M ³ , and a fine aggregate ratio of 55 to 65% by volume increases the flowability of the base concrete, improves the adhesion of sprayed concrete, and reduces the rebound rate. preferable.

Next, the unit water amount will be described. Base - Sukonkuri - unit water DOO is, 160~200kg / m ³ are preferred. If the unit amount of water is less than 160 kg / m ^3, base - Sukonkuri - DOO flowability decreases the viscosity increases, there is a tendency that pumpability is lowered, and when more than 200 kg / m ^3, coarse aggregate There is a possibility that the material and the mortar part / paste part may be easily separated, and either case is not preferable.

The ratio (weight ratio) of water / hydraulic powder is from 28 to
40% by weight is preferred. When the ratio is less than 28% by weight,
The fluidity of the base concrete decreases and the viscosity increases,
If the pumping performance tends to decrease, and if it exceeds 40% by weight, the coarse aggregate and the mortar / paste portion may be easily separated, and any case is not preferable.

Next, the base concrete contains a retarder,
The point that it is preferable to mix anhydrous gypsum and fiber will be described.

First, the retarder will be described. In the present invention, the base concrete may contain a retarder.
The "retardant" has an effect of reducing the hydration rate of the hydraulic powder and delaying the setting and hardening of the base concrete (kneaded material). The reason for blending the retarder is as follows. Depending on the environment and construction conditions at the construction site, the fluidity, viscosity and other properties of the kneaded base concrete may change over time, making spraying difficult or impossible. The compounding is carried out in order to suppress the time-dependent change of each characteristic of the glove, maintain the sprayable property for a long time, and promote the spraying operation.

In particular, the compounding of a retarder is effective in the following cases.・ When spraying is performed in the summer: Suppressing rapid changes over time in fluidity, viscosity, etc. of base concrete (kneaded material) manufactured under high temperatures (eg, 30 ° C) as in the summer. I do. -When kneading the base concrete (kneaded material):
Due to troubles in equipment and walls, spraying is stopped and repair and repair are performed for several hours.

The above-mentioned retarders include organic acids such as monocarboxylic acids, polycarboxylic acids, oxycarboxylic acids, and amino acids;
And their salts (sodium, potassium, lithium,
Calcium, magnesium, etc.).

Specifically: monocarboxylic acid; formic acid, acetic acid, etc. polycarboxylic acid; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid, terephthalic acid, etc. -Oxycarboxylic acid; heptonic acid, gluconic acid, glycolic acid, malic acid, tartaric acid, citric acid, salicylic acid, mandelic acid, etc .;-Amino acid; ethylenediamine tetraacetate (ED
TA), glutamic acid, aspartic acid and the like. As a commercially available product, for example, as an oxycarboxylic acid-based product, "POZORIS No. 8" manufactured by NMB Corporation
9 ", and an amino acid-based compound such as" Delvocrete "manufactured by the company.

The amount of the retarder is based on the hydraulic powder.
It is preferably 0.5% by weight (in terms of solid content) or less. 0.5
If the content is more than 10% by weight, the quick-setting property is reduced, and the rebound rate is increased. A more preferred amount is 0.01 to 0.2% by weight. The retarder may be used alone, but is preferably kneaded after premixing with other raw materials in advance.

In the present invention, the base concrete may contain anhydrous gypsum. The anhydrous gypsum has the effect of improving the pumpability of the base concrete and stabilizing the quality.

As the anhydrous gypsum, a commercial product can be used. The anhydrous gypsum may be blended simply or may be premixed with a hydraulic powder in advance. The fineness of the anhydrous gypsum is not particularly limited, but the specific surface area of the gypsum is 3,000 cm ^2.
/ G or more can be used without practical problems.

The amount of the anhydrous gypsum is preferably 3 parts by weight or less based on 100 parts by weight of the hydraulic powder. If it exceeds 3 parts by weight,
It is not preferable because the quick setting property and the compressive strength decrease.

Further, in the present invention, the base concrete may contain fibers. The fibers are blended to improve the resistance to bending load in the concrete after spraying. Examples of the fiber include steel fiber and vinylon fiber, and have a length of 60 mm or less, more desirably.
30 to 50 mm is compounded. The blending amount of the fiber is preferably 0.5 to 2% by volume based on the hydraulic powder.

The base concrete of the present invention may contain a high-performance water reducing agent or a high-performance AE water reducing agent. Examples of the high-performance water reducing agent or the high-performance AE water reducing agent include alkyl allyl sulfonic acid type, naphthalene sulfonic acid type, melamine sulfonic acid type, polycarboxylic acid type and the like, and both liquid and powder forms can be used. . The amounts of these components may be appropriately determined so as not to impair the properties of the base concrete.

Further, the base concrete of the present invention includes:
For example, an acrylic or cellulose thickener may be added.

In the wet spraying method according to the present invention, a conventional spraying device and other equipment can be used as they are. The spraying method will be described. The raw materials are kneaded with a conventional mixer, and a high-fluidity base is produced.
The screed is sent through a transport pipe by an ordinary concrete pumping machine to a spray nozzle, blown out from the nozzle with compressed air, and lined by spraying the concrete on a wall such as a tunnel. In this case, while the base concrete is being pressure-fed by a transport pipe, a few meters before the nozzle
The compressed agent is blown into the transport pipe with compressed air at the position (1), merged into the base concrete, and mixed in the transport pipe to the nozzle.

[0048]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention, together with Comparative Examples and Reference Examples.

The following materials were used in Examples, Comparative Examples and Reference Examples. (Raw materials used) ・ Hydraulic powder; Ordinary Portland cement [manufactured by Taiheiyo Cement Co., Ltd.] ・ Coarse aggregate: Crushed stone from Kajiri, Moji-ku, Kitakyushu (→ 2.80) ・ Fine aggregate: Crushed sand from Minami-ku, Kokura, Kitakyushu (→ specific gravity 2.69): Mixed fine aggregate of offshore sea sand (→ specific gravity 2.59) = 3: 7 (weight ratio) in Gonoura, Iki-gun, Nagasaki ・ Quick setting agent; trade name “Asanos-Par-Natom” [Taiheiyo Cement Corporation -Delaying agent [A]; trade name "Delvocrete" [manufactured by NMB Corporation] [B]; trade name "Pozoris No.89" [manufactured by NMB Corporation]-Anhydrite; [manufactured by Daiichi Cement Corporation] ] (Brain specific surface area → 4000 cm ² / g) ・ Steel fiber; Trade name “Tough grip” (→ 30 mm length, → specific gravity 7.8) [Bridgestone Metalpha Co., Ltd.] ・ Powder admixture; Calcium carbonate Powder (Brain specific surface area → 4200cm ² / g) [Okutama Kogyo Co., Ltd.] ・ High performance [A]; Trade name “NT-1000” [N-M Corporation] Water reducing agent [B]; Trade name "NT-1000S" [N-M Corporation] [C]; Trade name "NT-1000HP" [N-M Corporation] ・ Thickener; "THF" (acrylic) [manufactured by Taiheiyo Cement Corporation] ・ Water: tap water

(Examples 1 to 31, Comparative Example 1, Reference Example 1)
First, according to the formulations shown in Tables 1, 2 and 3, 20
At a temperature of ° C., materials other than the quick-setting binder were charged into a biaxial forced kneading mixer (0.1 m ³ ) and kneaded for 90 seconds to produce a base concrete (kneaded material). Comparative Example 1 is an example using a "400 mm" base concrete outside the range of the slump flow (450 mm or more) specified in the present invention.
Reference Example 1 is an example in which a conventional raw concrete (slump value: 210 mm) is used as a base concrete.

As shown in Tables 1 to 3, a quick setting agent was added to the base concrete to form a spray concrete.
A rasbotte was sprayed on a box carpet (note). The amount of each spray was 0.15 m ³ . In addition,
"Ariba 260" manufactured by Fuji Bussan Co., Ltd. was used as the spraying device, and "Q Gun" manufactured by Privlico Japan was used as the quick-setting agent supply device. (Note) Dimensions: width 2.5m x depth 3.0m x height 3.Om

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

With respect to the base concrete (kneaded material) immediately after the kneading and the spraying concrete, the following (1) to (7)
Are measured, and the measurement results are shown in Tables 4, 5 and 6. In each table, the ratio of water / hydraulic powder (% by weight), the amount of coarse aggregate (m ³ / m ³ ), and the fine aggregate ratio
(% By volume).

The measurement items are as follows. (1) Slump flow (mm); "JIS All II (Concrete
The slump cone is filled with the base concrete immediately after kneading in accordance with the method of “Slump test method for sludge”).
The length of the maximum diameter of the concrete expanded in the horizontal direction and the length in the direction perpendicular thereto were measured, and the average value was calculated. The degree of material separation can be confirmed by observing the state of the spread concrete. (2) Flowdown time (seconds) based on the V-Rot test; "Appendix 1. High-flow concrete" in the "Architectural Institute of Japan's Guide to High-flow Concrete Materials, Mixing, Manufacturing, and Construction (draft)" Of the consistency evaluation test method ". The time required for a certain amount of the base concrete immediately after the kneading to flow from the V-rot was measured by a stopwatch. (3) Presence / absence of pulsation: Presence / absence of pulsation at the time of pumping the base concrete was visually judged. "No pulsation" was evaluated as "O", and "Pulsation" was evaluated as "X". (4) Amount of sprayed concrete (m ³ / h): Measure the total volume of the sprayed concrete from the start to the end of spraying,
The amount of spray was calculated per unit time. (5) Rapid setting: The state of the adhered concrete immediately after spraying was evaluated by "touch", and the case where the squeezing was not possible was evaluated as "O", and the case where the squeezing was possible was evaluated as "X". (6) Rebound ratio (% by weight): After the spraying was completed, the weight of the concrete that had fallen without adhering was measured and calculated by the following equation. Rebound rate (% by weight) = [(weight of concrete dropped) / (total weight of sprayed concrete)] × 100 (7) Compressive strength (N / mm ² : material age 28 days), quality Stability (coefficient of variation): Concrete is sprayed on a wooden box measuring 30 × 40 × 20 cm, and three “φ5 × 10 cm” specimens are collected at 20 ° C.
After curing in moist air, the strength was measured according to "JIS AllO8 (Concrete compressive strength test method)", and the average value was calculated as the compressive strength. In addition, the stability of quality,
Evaluation was performed using a coefficient of variation (an index indicating variation) calculated from the strengths of the three test specimens.

[0057]

[Table 4]

[0058]

[Table 5]

[0059]

[Table 6]

Examples 32 to 41 Changes with time when the temperature of the concrete was changed were examined. With respect to the five formulations shown in Examples 15, 23, 26, 28 and 30 shown in Tables 1 and 2, base concretes (kneaded products) kept at 20 ° C. and 30 ° C. were produced, and 120 After standing still, a quick-setting admixture was added and sprayed. The measurement items are the same as those in Tables 4 to 6. Only the slump flow was measured at intervals of 30 minutes or 60 minutes from immediately after kneading to 120 minutes. Table 7 shows the obtained results. Example 32 containing no retarder
And 37 slump flows are 90 minutes and 60 minutes, respectively.
Minutes, but after that, slump was measured in place of the slump flow.

[0061]

[Table 7]

As is clear from Tables 4 to 6, in Examples 1 to 31 using the base concrete having the slump flow (450 mm or more) specified in the present invention, the spray amount per unit time And the rebound rate was small, no pulsation was observed during pumping, the coefficient of variation was small, and the quality stability was excellent.

Further, from Table 7, it can be seen that the base containing a retarder
In Examples 32 to 41 using screed, after kneading,
Even after 120 minutes, the slump flow range specified in the present invention is maintained, and the spray amount, rebound rate, pulsation, and stability of quality are excellent, and wet spraying is possible even at high temperatures. It was recognized that.

On the other hand, in Comparative Example 1 outside the range of the slump flow specified in the present invention, not only the amount of spray per unit time was small, but also the rebound rate was high, and pulsation was observed during pumping. The coefficient of variation was large and the stability of quality was low. Also, in Reference Example 1 using the conventional raw concrete, Comparative Example 1 was used.
Was similar to

(Examples 42 to 52, Reference Example 2) When excavating a tunnel and spraying concrete, unexpected spring water is generated from the exposed surface, and the sprayed concrete flows out. Construction may be inadequate. Then, spraying concrete was sprayed on a box carat equipped with a pipe capable of continuously springing water from a small hole, and the water stopping performance was examined.

A description will be given of a box-bart with piping. Six holes (diameter: 2 mm) were formed at 150 mm intervals on the outer surface of the box cage having the same shape and dimensions as those used in Examples 1 to 31 at a position of 2 m from the bottom surface and horizontally.
Iron pipes provided in rows (inner diameter 25 mm (outer diameter 27 mm), length 1
m) was prepared and used as a box-cart with a pipe. An iron pipe was attached to the hole so as to face downward. Then, tap water from one of the mouths of the steel pipe was
Water was passed at a rate of 8.0 and 10.0 liters / minute, and water was allowed to spring from each hole. The other end of the iron pipe was closed.

The formulation of the base concrete used is shown in Table 8 below. There are four types of base concretes (the ones of Examples 1 and 13 and the new type). Each formulation is as in Examples 1 to
Kneading is carried out in the same manner as in step 31, and the base concrete is kneaded.
(Kneaded material) was produced. Reference Example 2 is the same as the formulation of Reference Example 1 shown in Table 3.

Spraying (construction) of a spray concrete in which the quick-setting agent is added to and mixed with the base concrete (kneaded material) while water is passed through the iron pipe of the box-bart with piping. Was done. The spray amount was 0.06 m ³ .

Immediately after spraying, the water stopping state of each hole was observed to evaluate the water stopping performance. Whether or not the sprayed concrete hardens and closes the hole to stop the water can be easily determined by observing whether or not spring water is generated from the surface of the sprayed concrete. The water stop performance was evaluated as “〇” when all 6 holes were in the water stopped state, “△” when 4 to 5 holes were in the water stopped state, and “×” when 3 or less holes were in the water stopped state. went. Table 8 also shows the obtained evaluation results.

[0070]

[Table 8]

From the experiments shown in Table 8 and Examples 42 to 52, it was found that the slump flow of the base concrete was 450 mm or more and that the spray concrete containing the quick-setting additive was added.
It was found that the sprayed concrete stopped the spring water generated from the excavation wall surface and had sufficient water stopping performance. In particular, 5 to 10% by weight (proportion to hydraulic powder) of a quick setting agent was added to the base concrete having a hydraulic powder content of 530 to 700 kg / m ³ and spraying was performed. In this case, it was found that the water could be stopped sufficiently. In contrast, Reference Example 2 (conventional raw concrete
(A case where a quick-setting agent was added to the paste and used as a spray concrete), the water stopping performance was low.

[0072]

As described above in detail, the present invention can provide a wet spraying method with good working efficiency by using a base concrete having a slump flow of 450 mm or more. That is, without impairing quick-setting properties, pumping performance is good, and the rebound rate is small,
The spray amount per unit time can be increased.
For this reason, the spraying thickness can be made thinner than the conventional spraying concrete, the spraying time can be shortened, and the total spraying amount can be reduced, further shortening the construction period and reducing the cost. Is possible, and the practical value is extremely high.

Further, according to the construction method of the present invention, pulsation does not occur because the pumping property is good. For this reason,
Wet spraying with stable quality wet spraying concrete is possible, and the compressive strength (28 days old) is also 50N / mm.
Express ² or more.

Further, by blending a retarder, even when the base concrete is left at a high temperature (for example, in summer) or for a long period of time, wet spraying can be performed (in that case, each of the above-described methods). The advantage is not lost).

In addition, the wet spray concrete of the present invention
When the mixing amount of the hydraulic powder and the addition amount of the quick setting agent are limited, water can be sufficiently stopped even when sprayed on a construction site where spring water is generated.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takashi Ayata 2-4-2 Daisaku, Sakura City, Chiba Pref. Sakura Research Institute, Pacific Cement Co., Ltd. (56) References JP-A-6-264449 (JP, A) JP-A-6-240869 (JP, A) JP-A-4-342450 (JP, A) JP-A-9-78832 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E04G 21 / 02 103 C04B 28/02 E02D 17/20 104

Claims (11)

(57) [Claims] 1. Applicable to construction work of tunnels and underground structures
The amount of hydraulic powder is 45
0~700kg / m ^3, coarse aggregate amount 0.20~0.24m ³ / m ^3, fine
In aggregate rate 55 to 65% by volume, slump flow - is 450mm or more base - Sukonkuri - Doo, the relative hydraulic powder quick-setting admixture
Wet spraying method characterized by adding 4 to 10% by weight . 2. The wet spraying method according to claim 1, wherein a slump flow of said base concrete is 450 to 750 mm. 3. The wet spraying method according to claim 1, wherein a slump flow of the base concrete is 500 to 700 mm. 4. The time required for the base concrete to flow through the V-rot is 5 to 20 seconds.
4. The wet spraying method according to any one of items 1 to 3. 5. The compounding amount of the hydraulic powder in the base concrete is 530 to 700 kg / m ³ and the adding amount of the quick setting agent is 5
2 to 10% by weight (ratio to hydraulic powder).
The wet spraying method according to any one of Items 1 to 4 , wherein Wherein said base - Sukonkuri - claim maximum particle size of the aggregate in the bets is characterized in that it is 15mm or less 1-5
The wet spraying method according to any one of the above items. 7. The unit water content in the base concrete is as follows:
The amount is from 160 to 200 kg / m ³ .
6. The method for wet spraying according to any one of 6 above. Wherein said base - Sukonkuri - wet spray according to any one of claims 1 to 7, the ratio of water / hydraulic powder in the bets is characterized in that it is a 28 to 40 wt% Construction method. Wherein said base - Sukonkuri - DOO wet spraying construction method according to any one of claims 1-8, characterized in that it comprises a retarder. Wherein said base - Sukonkuri - wet spray installation method according to any one of claims 1 to 9, bets is characterized in that it comprises an anhydrite. Wherein said base - Sukonkuri - wet spray installation method according to any one of claims 1 to 10, bets is characterized in that it comprises a fiber.