JPH0336963B2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to a method of constructing a seawall, which has excellent strength against the scouring action of seawater, river water, etc., especially when reclaiming the sea or river. The present invention relates to a seawall construction method that can construct a stable seawall.

"Prior art and its problems" Methods for constructing seawalls for ports, rivers, dams, etc.
For example, by constructing an enclosure from the water's bottom to the water's surface with revetment walls such as caissons, steel pipe sheet piles, and steel plate cells, and filling the enclosure with filler materials such as chestnut stone and sand from the water's surface, allowing them to settle and accumulate. A method of constructing a seawall consisting of a seawall and a filling material is known.

In addition, chestnut stones, sand, etc. are usually poured into the water bottom outside the seawall built in this way from the water surface, and are allowed to settle and accumulate to protect the seawall from the scouring action of running water. Mounds are often constructed for this purpose.

However, this method of constructing a seawall has the following problems.

[1] Because sand is used as the filling material,
When sheet piles, etc. with low watertightness are used for the revetment wall, filler materials such as sand wash away from the gaps between the sheet piles, creating voids inside the revetment, and the filler material sinks, causing damage that can last for many years. There was a risk that the sea wall would collapse.

[2] Since the materials used to form the mound (hereinafter referred to as mound material) include chestnut stone and sand, there is a risk that the chestnut stone and sand will be washed away when the mound is scoured by running water. The mound in this situation was at risk of collapsing over a period of many years, just like the sea wall.

[3] Because the filling materials and mound materials are made of non-adhesive sand, cobblestones, etc., the seawall and the mound do not form an integral structure, resulting in a structure that does not have stable strength against vibrations caused by waves, earthquakes, etc. I had a problem with my sexuality.

"Means for solving the problem" Therefore, in the seawall construction method of this invention,
A plurality of slits are provided at the bottom of the revetment wall, and a filling material made of slurry is poured into the water bottom surrounded by the revetment wall, and a portion of the filling material is passed through the slits onto the water bottom outside the revetment wall. The above problem was solved by discharging the slurry into a mound to prevent scouring, and by integrating the mound, the revetment wall, and the filling material by hardening the slurry. .

Hereinafter, the seawall construction method of the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an example of a revetment wall suitable for carrying out the method of the present invention, and reference numeral 1 in the figure is a steel sheet pile cell (revetment wall). This steel sheet pile cell 1
is cylindrical, and this steel sheet pile cell 1 has an elongated rectangular through hole arranged along the circumferential direction of the steel sheet pile cell 1 at its lower part and along the longitudinal direction of the steel sheet pile cell 1. A plurality of slits 2... are formed.

This steel sheet pile cell 1 is submerged in water at a seawall construction site, for example, as shown in FIG. 2, and its lower part is buried in the bottom of the water and fixed in that position. The depth at which the steel sheet pile cells 1 are buried is preferably such that the lower ends of the slits 2 are not buried in the water bottom.

Next, an example of an apparatus for pouring slurry as a filling material inside the steel sheet pile cell 1 will be described with reference to FIG. 2. Reference numeral 3 in FIG. 2 is a mixer. The mixer 3 adds water to a material forming a slurry (hereinafter referred to as slurry material) and mixes the material to obtain a slurry S suitable for constructing a seawall. Above the mixer 3, there is a storage tank 4 for storing slurry material,
Storage tanks 5 for storing water are respectively provided, and these storage tanks 4 and 5 and the mixer 3 are connected by a raw material pipe 6. Water sucked from the water surface at the seawall construction site using a water supply pump 7 is sent to the storage tank 5 through a water supply pipe. In addition, mixer 3 has
An agitator 8 for further kneading the slurry S mixed by the mixer 3 is connected to the agitator 8, and a deaerator 9 for efficiently removing air bubbles in the slurry S is connected to the agitator 8. A pump 10 is connected to this deaerator 9, and this pump 1
0, a transport pipe 11 is arranged. Transport pipe 1
1 extends toward the water from the water surface at the seawall construction site, and its discharge port 12 is provided near the water bottom B in the steel sheet pile cell 1 described above.

The discharge port 12 is configured to be buried in the slurry S deposited on the water bottom B when the slurry S is discharged from the discharge port 12. The reason for this is that when slurry comes into contact with water and mixes with water, its properties change and the physical properties after solidification deteriorate. This is to discharge new slurry S.

Next, a method for constructing a seawall using the seawall constructed as described above and the slurry pouring device will be described.
First, the steel sheet pile cell 1 is driven into the water bottom of a seawall construction site using a steel sheet pile driving device such as a vibrating type such as a vibro hammer or a striking type such as a steam hammer, and is fixed at that position. Next, the transport pipe 11 of the slurry casting device is extended toward the water bottom B in the steel sheet pile cell 1, and the discharge port 12 is provided near the water bottom B. next,
Chestnut stone is thrown into the steel sheet pile cell 1 from the water surface. By introducing the chestnut stone in this way, the steel sheet pile cell 1, which is unstable due to external forces such as waves, before slurry pouring is not unnecessarily tilted due to external force, and the position is not shifted. It can be enriched. After making such preliminary preparations, the slurry material A in the storage tank 4 and the water B in the storage tank 5 are supplied to the mixer 3 in an appropriate ratio and mixed to obtain a slurry S.

As the slurry material used here, one having hydraulic properties is selected, and specifically, coal ash is preferably used. This coal ash is generated from coal-fired power plants and other coal-burning plants. A hardened product of coal ash slurry obtained by adding water to coal ash and mixing it by adding a hydraulic substance such as cement and hardening aids such as gypsum (hereinafter referred to as hardened coal ash slurry) It is possible to increase the strength of

Among hydraulic substances, the strength of cement increases as the amount of cement increases, but if it is added up to 5 parts by weight to 100 parts by weight of coal ash, the strength of the resulting hardened coal ash slurry can be increased to the ground of the seawall. It can be made suitable and strong. Calcium-based hardening materials such as granulated slag and raw coal can be expected to have the same effects as cement. In addition, in the case of plaster, it is usually 2
The optimum amount is 10 parts by weight, but up to 50 parts by weight can be used. Furthermore, adding gypsum when adding cement is very effective, and usually cement and gypsum can be added at a ratio of about 1:2. In this case, the gypsum includes anhydrous, semi-hydrous, and dihydric gypsum, but
There is an optimum value for each amount added. Furthermore, aggregates such as sand, gravel, and bottom ash may be added to the coal ash to the extent that they do not impair the fluidity of the coal ash slurry. The addition of aggregate also increases the strength of the hardened coal ash slurry after pouring.

In this way, hydraulic substances such as cement, curing aids including gypsum, aggregates, etc. are added to coal ash.
By adding water to this and mixing it, a cured coal ash slurry can be obtained. The range of compressive strength required for this cured coal ash slurry when constructing a seawall is about 10 to 20 Kgf/cm ² . 20Kgf/
If it exceeds cm ² , it exceeds the strength required to construct a seawall, and the strength and stability that can be obtained reaches a plateau, making it uneconomical. Moreover, if it is less than 10 kgf/cm ² , it does not have sufficient strength necessary for constructing a seawall and cannot be used normally.

Furthermore, in addition to regular tap water, well water, and other clean water, seawater, lake water, rainwater, and the like can also be used as water. In particular, seawater and lake water are suitable for use in landfills and the like because they are easily available and inexpensive.

Next, after thoroughly kneading the slurry S with an agitator 8, it is degassed with a deaerator 9, and the slurry S
A predetermined amount of the steel sheet pile is poured into the steel sheet pile cell 1 by a pump 10 via a transport pipe 11. The slurry S cast in this manner is deposited and filled into the steel sheet pile cell 1. Then, a part of the slurry S is discharged from the plurality of slits 2 to the outside of the steel sheet pile cell 1,
It spreads outward in the radial direction on the water bottom around the outside of the steel sheet pile cell 1, and is deposited to form a substantially conical mound 13. Next, when a predetermined amount of the slurry S has sufficiently hardened, more slurry S is cast while the transport pipe 11 is pulled upward to construct a seawall.

In addition, in the above embodiment, the steel sheet pile cells 1 are used for the revetment wall, but sheet piles 14 as shown in FIG. 3 may also be used. A slit 15 similar to the steel sheet pile cell 1 is formed in the lower part of the sheet pile 14. When such a sheet pile 14 is used, it is possible to construct a seawall with excellent strength and stability, similar to the above embodiment.

Hereinafter, experimental examples will be shown to clarify the effects of the seawall construction method of the present invention.

(Experiment Example 1) The slump value of the coal ash slurry used in the seawall construction method of the present invention was measured using a slump cone with a height of 15 cm, and the slump value of the coal ash slurry was measured when the coal ash slurry was poured into water. The inclination angle (flow gradient) of the edge of the cured product was measured. These correlations are shown in FIG.

As is clear from this result, when coal ash slurry is used as the filling material, it is possible to control the casting angle by controlling the fluidity. Therefore, by adjusting the fluidity of the coal ash slurry, a mound having a stable inclination angle can be formed.

(Experimental Example 2) Cement was added to coal ash slurries having various densities, and the unconfined compressive strength of each hardened coal ash slurry was measured. The measurement results are shown in FIG. The density range of coal ash slurry is approximately
0.9 to 1.4 g/cm ³ , and the amounts of cement added were (a)...0% by weight, (b)...2% by weight, and (c)...5% by weight, respectively. The age of the cured coal ash slurry used in this experiment was 28 days.

As is clear from these results, when coal ash slurry is used as the filling material, the strength of the finally obtained hardened coal ash slurry depends on its density and the amount of cement added. Therefore, the density of the coal ash slurry to be cast and the amount of cement to be added to the coal ash can be determined by taking into consideration conditions such as waves and tidal currents at the seawall construction site.

"Effects of the Invention" As explained above, according to the seawall construction method of the present invention, a substantially conical mound made of slurry that spreads outward in the radial direction of the seawall is provided on the water bottom around the outside of the seawall. By curing this slurry and integrating it with the seawall and filling material, it is possible to construct a strong mound against scouring by seawater, for example, and also to make this mound It is possible to construct a seawall with excellent strength and stability against vibrations such as waves and earthquakes.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a revetment wall body used in the revetment construction method of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of a slurry pouring device suitably used in the revetment construction method of the present invention. 3 are schematic configuration diagrams showing other examples of the revetment wall used in the revetment construction method of the present invention, and FIGS. 4 and 5 show the coal ash slurry used in the revetment construction method of the present invention. FIG. 4 is a graph showing the characteristics, and FIG. 4 is a graph showing the relationship between the slump value and flow gradient of the coal ash slurry, and FIG. 5 is a graph showing the relationship between the density and hardening strength of the coal ash slurry. 1... Steel sheet pile cell (revetment wall), 2, 15... Slit, S... Slurry (filling material), 13... Mound,
14...Sheet pile (revetment wall).

Claims (1)

[Claims] 1. A plurality of slits are provided in the lower part of the revetment wall, a filling material made of slurry is placed in the water bottom surrounded by the revetment wall, and a part of the filling material is passed through the slits to the water bottom outside the revetment wall. A method for constructing a seawall, characterized in that a mound for preventing scour is provided by discharging slurry upward, and the mound, a seawall wall, and a filling material are integrated by hardening slurry.