JP2001225037A - Seepage control and bank protection construction method of waste disposal site - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seepage control and bank protection construction method which is advantageous to construction work efficiency and costs with respect to the seepage control and bank protection of a waste disposal site. SOLUTION: In the construction method, fly ashes are used as a chief material and a small amount of cement and sea water or water, in proper quantities, is added to the fly ashes, which are kneaded to provide a fly ash mortar, and just before the mortar is placed on a mortar placing spot, e.g. underwater spot, a small amount of aluminium sulfate is mixed into the mortar. The aluminium sulfate is mixed into the mortar on a transship line where the fly ash mortar is transshipped from a truck mixer car to a concrete pump car, so that, while the mortar is being agitated and mixed in the concrete pump car, the forward end of a mortar transfer pipe is put into the mortar placing spot, e.g. underwater spot, to place the mortar.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a seawall at a waste disposal site, and more particularly to a seawall construction at a waste disposal site for promoting early hardening of fly ash mortar in water or the like. About the method.

[0002]

2. Description of the Related Art Conventionally, powdery industrial waste such as coal ash, incineration ash, and slag generated from plants such as coal-fired power plants, garbage incineration facilities, and smelters, and general waste, etc. In the case of disposal, it is necessary to divide the sea area where the final disposal site will be installed as a seawall so as to prevent harmful leachate from these landfills from contaminating the surrounding groundwater and public waters. As a conventional revetment structure of such a waste disposal site, a seawall, a steel sheet pile, a steel pipe sheet pile, or a revetment wall such as a steel sheet cell, which was built up from the bottom of the water and built up, was constructed as an enclosure. There is known a water-blocking revetment structure by a filling method in which a filling material such as sand and crushed stone is put into the enclosure and settled and deposited. In addition, as a water-blocking (water-blocking) seawall structure for a rubble slope, the permeability coefficient is 1 × 10 ⁻⁶ cm.
In general, construction is carried out using a water-impervious sheet and a padded soil (sheet holding material) so as not to exceed the value of / sec.

[0003] Since these filling materials such as sands and crushed stones and abdominal earth and the like have no adhesive force, pressure changes due to changes in tide level and waves.
Deterioration due to liquefaction due to vibrations or corrosion of steel materials has a problem with long-term durability. Therefore, recently, fly ash mortar (commonly referred to as fly ash cement slurry) in which fly ash is mixed with a small amount of hydraulic material such as cement and water is used as a substitute for the conventional filling material, water-blocking sheet, and belly sand. As a material, it is practiced to be cast in water and integrated. For example, Japanese Patent Publication No. Hei 5-77804 and Japanese Patent Application Laid-Open No. Hei 10-37158 have been proposed as a method for placing the steel in an enclosure constructed of a seawall. Japanese Patent Laid-Open Publication No. 59-11890 discloses a method in which a seawall, a lake, a marsh, or the like is settled freely on the bottom without using an enclosure of a revetment wall.
No. 8 and JP-A-60-139381 have been proposed.
However, in these proposed water-blocking revetment construction methods, no attempt has been made to promote the hardening of fly ash mortar in water.

[0004] For example, when fly ash mortar is cast in water on a rubble-inclined embankment or the like as a substitute for a combination of a water-blocking sheet and a padded earth and sand, since the mortar is hard to harden, the inclination rate of the inclined surface (vertical height) is reduced. Length / horizontal length)
When the ratio is about 1: 1.5, even if it is to be poured in order from the bottom (the bottom of the water) along the inclined surface and try to pile up, the hardening is slow and the flow is dissipated to the front (offshore side) and the casting surface is It is not finished as a seawall with the water permeability and strength as specified, and the amount of installation (loss) in areas other than the design cross section is large, and the height of each installation along the slope However, there is a problem that the efficiency of the construction work is inferior and a long time is required because the number of times of casting increases because the size cannot be large.

Further, when an enclosure is constructed with a revetment wall body and fly ash mortar is poured into the enclosure as underfill in the enclosure, if there are some gaps in the enclosure, spillage due to its own weight or seawater will occur. The mortar is easily dissipated and flows out under the influence of the pressure due to the tide level.
In general, a certain amount of solidification strength can be obtained even if the amount of cement is small, but it takes several days to harden to a predetermined shape inside the formwork, so that there is a problem that the efficiency of construction workability is low. As described above, there has been a strong demand for measures to improve workability and cost in the case where conventional fly ash mortar is poured underwater.

[0006]

In view of the current situation,
It is an object of the present invention to provide a method for constructing a seawall with a seawater revetment which is advantageous in terms of construction workability and cost as a response to the seawater revetment of a management type (including a stable type and a shield type) waste disposal site. It is. Further, an additional problem of the present invention is that a waste disposal site capable of efficiently constructing a seawall with a strength and permeability as designed in an enclosure constructed of an underwater slope or an underwater seawall. The purpose of the present invention is to provide a method for constructing a seawall.

[0007]

As a result of various studies to solve the above problems, it has been found that a small amount of aluminum sulfate is blended immediately before the fly ash mortar is poured into a place to be poured in water, thereby enabling the early use of the fly ash mortar. It has been found that curing is promoted and the above-mentioned problems can be solved, and the present invention has been completed. That is, the method for embankment of a water disposal site according to claim 1 of the present invention is a fly ash mortar comprising fly ash as a main material, a small amount of cement and an appropriate amount of seawater or water, and kneading. A small amount of aluminum sulfate is compounded immediately before casting at a casting location such as underwater.

According to a second aspect of the present invention, the mixing of the aluminum sulfate according to the first aspect of the present invention is performed in a transfer line from a truck mixer truck to a concrete pump truck for fly ash mortar, and the concrete pump truck is used. It is characterized in that the tip of the mortar pressure feeding pipe is extended to a casting location such as in water while being stirred and mixed, and is then cast. This is particularly preferable in terms of both fly ash mortar performance and work efficiency.

According to a third aspect of the present invention, there is provided the present invention, wherein the placing site is a rubble slope embankment from a water bottom to a surface of a waste disposal site, particularly a slope ratio (vertical height / horizontal direction). (Length) is specified as an inclined surface of 1: 1.5 or less, and can be freely cast, thereby forming an inclined surface as a revetment part having sufficient strength and water shielding. it can. Furthermore, the invention described in claim 4 of the present invention
The pouring point in the present invention is an enclosure built with a seawall built up from the bottom of the water at a waste disposal site and provided as a filling material that is not easily affected by pressure due to sea level change. It can be suitably applied.

[0010]

Embodiments of the present invention will be described below in detail. The present invention is mainly based on fly ash (collected by a dust collector), which occupies most of coal ash discharged in large quantities from coal-fired power plants and the like. Fly ash itself has poor self-hardening properties.However, fly ash mortar material obtained by adding a small amount of cement and an appropriate amount of seawater or water and kneading it has hardening properties and hardly separates in water. It is used as a substitute for soil and filling material. The cement used in the present invention is not particularly limited, and plain cement such as Portland cement, various mixed Portland cements and the like can be used as long as the cement has ordinary hydraulic properties. Also, the greater the amount of cement added to fly ash, the more advantageous in terms of strength, but disadvantageous in terms of cost.
Used within the range of%.

Among them, as a substitute for the water-blocking sheet and the earth and sand, the rubble slope levee (the upper limit of the slope rate is 1:
In the case of casting to about 1.5), it is desirable to mix the cement in the fly ash mortar so as to be 3 to 10% by weight, preferably 4 to 9% by weight. On the other hand, when casting as a filling material inside the formwork for constructing the seawall, the cement is contained in the fly ash mortar mixture in an amount of 2 to 6 wt%, preferably 3 to 5 watts.
It is desirable to mix t%.

Here, a method for producing the fly ash mortar of the present invention will be described. First, fly ash (f)
Since the cement (c) is as small as 10 wt% or less with respect to the mixed powder (f + c) of the cement and the cement, it is important to mix the two powders in advance until they become a homogeneous mixture. Next, it is desirable to mix and knead the homogeneously mixed powder with a continuous paste mixer or the like while mixing water (or seawater), and then to sufficiently knead with a forced twin-screw mixer or the like for a predetermined time. The mixing amount of water to be mixed here is not particularly limited, but the mixed powder (f + c) 100
30-60 parts by weight, preferably 35-5 parts by weight
About 0 parts by weight is desirable. Here, the fly ash mortar, which has been sufficiently mixed, receives an appropriate amount by a truck mixer truck via a delivery chute, transports the mortar to a casting site, and reloads the concrete pump truck. In the present invention, it is important to add aluminum sulfate in the transshipment line from the truck mixer truck to the concrete pump truck just before the casting.

Here, the aluminum sulfate [Al ₂ (SO ₄ ) ₃ .nH ₂ O] added in the present invention is also known as “sulfate band”.
As a general-purpose chemical substance, it is easily soluble in water, and the aqueous solution is acidic (about pH 3.0). When neutralized, white colloidal aluminum hydroxide precipitates. Typical main uses include flocculants for water purification, sizing agents,
It is known for fire extinguishers, etc.
There are cases where it is also used for pigments and the like.

The inventors of the present invention have conducted various studies on the method of placing fly ash mortar on a seawall with impermeable construction, and particularly studied the hardening of mortar in water. As a result, when a small amount of aluminum sulfate was added, It has been found that curing is significantly accelerated. The effect of this aluminum sulfate to promote hardening was measured by the concrete slump test (JIS
In comparison with the case where aluminum sulfate is not added in A1101), the slump changes rapidly, so that it can be easily confirmed. It is considered that such a hardening acceleration property is mainly caused by ettringite generated by reaction of aluminum sulfate with cement.

Therefore, even if the amount of cement is increased, it is expected that ettringite will remain in the hardened body for a long period of time and the development of long-term strength will be slightly reduced. Not preferred. In the case of the present invention, the addition amount of aluminum sulfate is
Depending on the compounding ratio of the cement in the fly ash mortar, when the compounding ratio of the cement is 2 to 10 wt%,
1 wt% or less of the mixed powder (f + c), preferably 0.3%
About 0.8 wt% is desirable. This blending amount is 1wt%
If the amount is more than the above, cracks (cracks) are likely to occur in the cured product, which is not preferable.

Next, a method of placing a steel sheet in a place where a water barrier wall is formed will be described in detail. Aluminum sulphate is added at the line where the fly ash mortar is transferred from the discharge part (chute part) of the truck mixer truck to the concrete pump truck. While mixing and stirring with the concrete pump truck, the pressure is increased by the pump and the tip is passed through the mortar pumping pipe. It is preferable that the part is extended in a state where the part is extended to the part to be driven. In this case, the placement site may be an underwater (seawater) portion or a land portion as long as the location for constructing the seawall of the waste disposal site is constructed.

In particular, the casting locations where the present invention is effective are:
This is a sloping rubble from the bottom to the surface of a waste disposal site located on the waterfront, and a revetment wall built up from the bottom to the surface. When placing on a rubble sloping dike from the bottom of the water (seawater) to the surface of the water, the tip of the mortar pumping pipe is submerged and the tip is manually operated by a diver or a robot arm. It is particularly desirable in terms of both mortar performance and work efficiency to move and place while confirming the slope ratio of the rubble slope levee in the underwater placing section by using the machine operation used.

In the case where the mortar is to be poured into the area surrounded by a seawall built up from the bottom of the water and installed, the tip of the mortar pumping pipe is laid while maintaining the state of being buried in the fly ash mortar. It is preferred to lift while pulling. As a result, it is possible to suitably lay as a filling material that is not easily affected by the pressure due to the tide level change of the seawater in the enclosure constructed with the seawall. In addition, caisson, steel sheet pile, steel pipe sheet pile, formwork, etc. are mentioned as what comprises a revetment wall body.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. Example 1 In order to confirm the effect of accelerating hardening when the addition amount of aluminum sulfate (also called sulfuric acid sulfate) was changed to fly ash mortar, the results of slump test (JISA1101) were performed, and the following results a) to e) were performed. Shown in However, fly ash mortar is based on 100 parts by weight of a mixed powder of 10 wt% of cement (Portland cement) and 4 parts of seawater.
It was mixed at a ratio of 5 parts by weight and kneaded. <Aluminum sulfate addition amount><Slumpchange> a) 0 → 0.31 wt% 20.8 → 11.6 cm b) 0 → 0.40 wt% 18.9 → 9.8 cm c) 0 → 0.51 wt% 4 → 10.4cm d) 0 → 0.62wt% 18.5 → 7.8cm e) 0 → 0.69wt% 21.5 → 4.7cm The slump test was conducted according to JISA1101 for concrete.
Slump cone (top diameter 10c)
(m, bottom diameter 20 cm, height 30 cm) after filling the mortar sample according to the standard, gently pulling up the cone vertically, and measuring the degree of decline of the top of the mortar sample with a slump measuring instrument. As a result, in each of the formulations, the slump rapidly changed from the state in which aluminum sulfate was not added to the state in which aluminum sulfate was added, indicating that the curing was accelerated at an early stage.

Example 2 A putt test (confirmation of expandability) was carried out to confirm the upper limit of the amount of aluminum sulfate added to fly ash mortar of the same raw material used in Example 1. The amount of cement in the mixed powder was changed to 3, 6, and 10 wt%, and 100 parts by weight of the mixed powder homogeneously mixed was mixed with 45 parts of seawater.
For each fly ash mortar produced by mixing and kneading at a ratio of parts by weight, each fly ash mortar adjusted by changing the amount of aluminum sulfate added was cured on a glass plate, and then put in seawater. The state of destruction was observed. The results are shown in Table 1 below.

[0021]

[Table 1]

According to the results shown in Table 1, when aluminum sulfate was added in an amount of 5 wt% or more, cracking was observed in the test specimen. Because the cause is expansion, the addition amount of aluminum sulfate is 5 wt%.
It must be: In addition, the larger the amount of cement compounded, the stronger the tendency of expansion.
%, The addition amount of aluminum sulfate is desirably 1 wt% or less.

Example 3 Fly ash, cement and seawater were previously kneaded using the same raw materials as those used in Example 1 as a standard blend, and aluminum sulfate was added at the following ratio immediately before casting: Fly ash: 1,026 Kg / m ³ · cement: 114Kg / m ³ · seawater: 513Kg / m ³ · aluminum sulfate: 5.7 kg / m ³ mix uniformly kneaded with concrete pump truck to be (mixed powder of about 0.5 wt%) of The final adjusted fly ash mortar is placed on a sloping dike with a water depth of 6.50 m at low tide, 8.01 m at high tide, and a revetment slope of about 1: 4/3, over a width of 10 m, and the slope of the design line (1: 1). The diver cast the underwater while moving the tip of the mortar pumping pipe in the water so that it became the seawall of (5)). As a result, the continuous operation was carried out six times with an interval of about 30 minutes until the next lift-up at an average casting amount of 66 m ³ per one shot, a casting speed of about 16 m ³ / hr without a formwork. With the number of castings, the seawall with the slope of the design line (1: 1.5) was obtained. The hardened layer of fly ash mortar cast on the inclined surface has sufficient water shielding (10 ⁻⁷ cm /
s order) and strength.

Comparative Example 1 In Example 1, except that a fly ash mortar adjusted without adding aluminum sulfate was used, a similar slope was used, and the slope of the design line was 1: 1.5. A diver drove the mortar transfer tube underwater while moving it underwater. As a result, a slope having a gradient of 1: 1.5 or less can be formed without using a mold, but since fly ash mortar takes a long time to harden in water, it takes about 4 hours or more before the next lift-up. It was necessary to take water curing time. In addition, in order to suppress the flow to the front (offshore side), the per-cast height must be limited to 0.5 m or less, and the number of times per cast is 17 times before finishing the design section. But the slope of the design line (1:
1.5) Only a considerably gentle slope was obtained. In particular, there was a large amount of loss (discharge) due to the escaping flow to the part other than the designed section (offshore side) at the lower part (sea floor) of the casting section.

[0025]

According to the present invention, the hardening of the fly ash mortar is accelerated in a short time by blending the fly ash mortar, especially a small amount of aluminum sulfate immediately before casting in water. Therefore, especially when the seawall slope is 1: 1.5, sufficient water shielding (10 ^-7) can be achieved in a short time.
(cm / s order) and the strength of the waste disposal site, and the embankment of the rubble slope from the bottom to the surface can be constructed. Further, since the slump at the time of producing fly ash mortar can be set large, mass production and continuous transportation are possible. Furthermore, since the casting loss outside the design cross section can be reduced, and no formwork is required when casting underwater or on land, it is extremely advantageous in terms of construction workability and cost. In addition, compared to the conventional structure of the impermeable sheet and the padded soil (sheet holding), the thickness can be reduced and the landfill capacity of waste can be increased even if the development area is small.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Isao Notohara, Inventor 6-15-1, Ginza, Chuo-ku, Tokyo Inside Power Development Co., Ltd. (72) Tetsuharu Ogata 1-6-5, Shinjuku, Shinjuku-ku, Tokyo F term (reference) 2D018 DA00 4D004 AA37 BA02 BB04 CC11 CC13

Claims (4)

[Claims] 1. A fly ash mortar containing fly ash as a main material, mixed with a small amount of cement and an appropriate amount of seawater or water, and kneaded with a small amount of aluminum sulphate immediately before being poured into a place to be poured into water or the like. A method for constructing seawalls at a waste disposal site, which comprises mixing water. 2. The aluminum sulphate is mixed in a fly ash mortar from a truck mixer truck to a concrete pump truck in a reloading line, and the tip of the mortar pumping tube is mixed with water while stirring and mixing with the concrete pump truck. 2. The method for embankment of a seepage control work at a waste disposal site according to claim 1, wherein the method is carried out by extending to a casting site. 3. The method of claim 1 or 2, wherein the casting site is a rubble slope from the bottom to the surface of the water at the waste disposal site. 4. The embankment construction of a waste disposal site according to claim 1 or 2, wherein the casting site is an interior surrounded by a revetment wall body which is set up on the water from the bottom of the waste disposal site. Method.