JPH03156024A - Placement of premix to seabed and work ship therefor - Google Patents

Abstract

PURPOSE:To crease artificial ground of excellent quality in the seabed by slightly burying, in the seabed ground, the lower end of a sliding head that is connected to a flexible pipe coupling of a ship main body, and by conveying and discharging slurried premix through the above-mentioned apparatus. CONSTITUTION:The lower end of sliding head 5 fixed to the front end of a placing pipe 3 that is rotatably hinged with a flexible pipe coupling 4 to a pipe support member 2a of a support body 2 on the rear side of a ship main body 1 is slightly buried in te seabed ground, and slurried premix is conveyed from the ship main body 1 and is discharged. As the occasion demands, a floating means is provided to the sliding head 5 and delivery of the premix is made continuously in repetition for placement, with the depth of burying of the lower end of the sliding head 5 kept by adjustment made with cables 7, 8 and 9 that adjust the positions on the lower end of a through hole through which the discharge is made. Thereby the artificial ground of excellent quality having a specified characteristic value can be created in the seabed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a mixing process ± (hereinafter simply referred to as pre-preparation) in which cement, clay, etc. made wet by crushing mountain sand and mudstone are mixed with seawater. This prevents the premix from scattering into the seawater when pouring the premix into the seabed, and the premix can be poured into the seabed without further mixing seawater into the premix. The present invention relates to a method for casting a premix on the seabed and a premix casting ship suitable for carrying out this method.

[Conventional technology]

Conventionally, as a method for artificially creating ground by reclaiming a predetermined area in a sea area, the method generally used was to simply deposit dredged soil, mountain sand, etc. on the ocean floor. In other words, since the purpose of conventional artificial ground creation is to construct houses, factories, etc. on the created artificial ground, it is necessary to create artificial ground with dredged soil, mountain sand, etc. exposed to the sea. Therefore, after surrounding the area where you want to create artificial ground with steel sheet piles or constructing a bank, dredged soil, mountain sand, etc. can be deposited in the area until it is exposed above the sea surface, and then compacted. It had been.

However, if it is necessary to connect an artificial island with an undersea tunnel, such as the Kisarazu artificial island of the Tokyo ditch crossing road currently being planned, the undersea tunnel will be constructed by excavating the undersea ground. A ramp is required near the entrance/exit from land, that is, along the coast of the artificial island.
There is a problem that cannot be solved using conventional technology: how to create artificial ground in the sea with a gentle slope that matches the slope of the slope of an undersea tunnel.

In other words, the sloping artificial ground that is created on the seabed in order to penetrate an undersea tunnel must be located below the sea surface and have appropriate unconfined compressive strength, density, and low permeability for the undersea tunnel to be excavated. As mentioned above, these conditions cannot be achieved with conventional artificial ground, which is performed by depositing dredged soil, mountain sand, etc. and compacting it. This is because artificial ground created by accumulating dredged soil, mountain sand, etc. and compacting it does not have the uniaxial compressive strength to prevent damage when excavating an undersea tunnel later. This is because a buoyant force is generated in the tunnel, resulting in an unstable state, and the tunnel does not have low water permeability to prevent water from entering the tunnel after excavation.

Therefore, a premix was devised, which is a mixed soil made by mixing seawater with clay made by crushing cement, mountain sand, and mudstone into a wet slurry. This premix includes, for example, cement = 4.2% by weight, mountain sand: 62.4% by weight, and clay: 5% by weight.
．． 8% by weight, seawater: 27.6% by weight. However, the above-mentioned premix is in the form of a slurry containing a large amount of seawater, and if this premix is simply discharged onto the seabed soil, seawater will be mixed with the premix and the seawater content will be high. This not only made it impossible to obtain the conditions necessary for the artificial ground to form the ramp section of the submarine tunnel, but also caused the problem of muddying the surrounding seawater, leading to environmental destruction. In particular, construction of artificial ground is carried out from the sea, so a work boat is usually used, but rolling motion occurs when the boat rotates around the longitudinal horizon due to the influence of waves. and vertical shaking (
In addition to pitching (heaving) and pitching (pitching), which causes vertical displacement due to the rotational movement, there are six types: surging (surging), swaying (swaying), and yawing (yawing), which involve displacement in the horizontal plane. Since the shaking causes complex shaking, when the premix in the form of a slurry is pumped into the pipe, which can be regarded as a rigid body simply extending from the ship to the seabed, and is poured into the seabed, the discharge part of the pipe is There is a problem in that the premix that is discharged from the discharge part moves with the shaking of the vessel and is scattered into the sea, and there has been no suitable method for depositing the slurry-like premix into the seabed soil. be.

[Problem to be solved by the invention]

Therefore, the present invention aims at pouring a slurry-like premix onto the seabed without further mixing seawater with the premix and without causing the premix to be poured into the seabed. An object of the present invention is to provide a method for placing a premix on the seabed, which can create high-quality artificial ground without polluting seawater, and a premix placing ship suitable for carrying out the method. do.

[Means to solve the problem]

As a result of various studies conducted by the present inventors to solve such problems, we found that the scattering of the premix into the sea and the mixing of seawater into the premix are caused by the discharging of the premix that has already been discharged onto the seabed or onto the seabed. Since the premix is discharged at a position far from the surface, the newly discharged premix mixes with seawater and scatters before reaching the seabed ground or the surface of the already discharged premix, and the premix is scattered on the seabed or the already discharged premix. Focusing on the fact that collision with the surface of the ship further promotes mixing and scattering with seawater, we developed a sliding head that is fixed at the end of the pouring pipe that pumps the slurry premix from the ship. The present invention was completed by discovering that it is sufficient to discharge the premix from the through hole of the sliding head while it is slightly buried in the seabed ground and/or the surface of the already discharged premix.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, a premix casting method according to the present invention on the seabed and a premix casting ship according to the present invention suitable for carrying out the method will be described in detail.

FIG. 1 is an explanatory diagram showing a state in which a slurry-like premix is being poured into seabed ground by an embodiment of a premix pouring vessel suitable for carrying out the method of the present invention, and FIG. Figure 3 is a cross-sectional explanatory diagram showing an example of a support body, Figure 4 is a cross-sectional explanatory diagram showing an example of a flexible pipe joint, and Figures 5 (a) and (b) are An explanatory diagram showing the displacement of the sliding head and casting pipe due to the shaking of the ship body due to sea waves, Figure 6.Sliding head and the displacement due to the movement of the ship body moving to continuously pour premix. FIG. 7 is an explanatory diagram showing the displacement of the casting pipe, and FIG. 7 is an explanatory diagram showing the state in which the premix is cast into the seabed ground.

First, to briefly explain the method of the present invention, when pouring a slurry-like premix into seabed soil, the method uses a sliding head fixed to the end of a pouring pipe that pumps the premix from a ship. A seabed premix characterized in that the premix is cast into the seabed by continuously discharging the premix while keeping the lower end slightly buried in the seabed and/or the surface of the already discharged premix. This is the pouring method.

The method of the present invention will be described in detail while explaining a premix pouring vessel suitable for carrying out the method of the present invention.

A premix pouring ship suitable for carrying out the method of the present invention has a support 2 fixed on a ship body 1, on which a pipe support 2a is rotatably mounted around a substantially horizontal line. As shown in FIG. 3, for example, a tube support portion 2a having a circular cross section is rotatably mounted on the support body 2 with its axis substantially horizontal via a thrust/radial bearing. It is preferable for the structure of the ship that this support body 2 be attached to the rear of the ship body 1, and the tube support portion 2a of the support body 2 has at least two flexible tubes provided at intervals. Casting pipe 3 divided into two or more parts by a joint 4
The end of the pouring pipe 3 is pivoted, and the pipe support 2a is pivoted in the support 2 so as to be rotatable about a substantially horizontal line, so the pivot at the end of the pouring pipe 3 is substantially horizontal. It remains rotatably pivoted around a line. If there are two flexible pipe joints 4 that divide this casting pipe 3, one may be provided at the end opposite to the support 2, and the other may be provided in the middle of the casting pipe 3. As shown in FIGS. 5 and 6, two flexible pipe joints 4 are provided in the middle of the casting pipe 3, and the inlet casting pipe 3a and the two flexible pipes are pivotally connected to the pipe support 2a. An intermediate casting pipe 3b located between the joint 4 and an outlet casting pipe 3 located on the opposite side of the intermediate casting pipe 3b to the entry casting pipe 3a.
It is preferable that the inlet casting pipe 3 is divided into two parts.
A flexible tube 11 that can be displaced while communicating with the entrance pouring tube 3a is connected to the middle of the tube a, and the slurry premix that is pumped through the transfer tube 10 is transferred to the flexible tube 11. It is pumped into the pouring pipe 3 through. This flexible pipe joint 4 has two arms 4aa on both sides as shown in FIG.
The lower connecting metal fitting 4a is pivotally connected to the lower connecting metal fitting 4a, which also has two arms 4ba on both sides, and a circular ring is attached to the tip of the two arms 4ba by a pin 4bb at a position 90 degrees offset from the pivoting position by the pin 4ac. 4ab, and a flexible pipe 4c that connects the lower connecting fittings 4a and the upper connecting fittings 4b in a state where they communicate with each other, and the four pins 4ac and 4bb. Due to this action, the positional relationship between the lower connecting metal fitting 4a and the upper connecting metal fitting 4b has a structure in which the flexible pipe 4c can be freely displaced without applying an unreasonable force to the flexible pipe 4c. As a result, the entry side casting pipe 3a and the intermediate casting pipe 3b are in a state where they can be bent around the flexible pipe joint 4 on two planes with two orthogonal sets of pins 4ac and 4bb as two rotation axes. It will be divided. Further, the same applies to the intermediate casting pipe 3b and the outlet casting pipe 3c. Furthermore, the pipe support part 2 of the pouring pipe 3
A sliding head 5, which has a through hole 5a formed in the center, connects the through hole 5a and the exit side casting pipe 3 at the end opposite to a.
It is fixed in a state where it is aligned with the hole c. This sliding head 5 may have any shape as long as it can be slightly buried in the surface of the seabed ground 13 and/or the already discharged premix 12 discharged onto the seabed ground 13 and move along the surface. As shown, it is preferable that the peripheral edge has a trapezoidal cross section that is inclined toward the through hole 5a from the upper end to the lower end, and the area of the lower end is such that the sliding head 5 is not completely buried in the discharged premix 12. It is sufficient if the sliding head 5 has a width of
It is preferable that a float means 5b is provided so that the weight in the water can be adjusted so that it is slightly buried in the surface of 2, and this float means 5b is preferably attached as shown in FIG. 2, for example.

Further, it is preferable that the through hole 5a of the sliding head 5 is provided with a lid 5c that can be opened and closed so that the sliding head 5 can temporarily stop discharging the premix when starting to place the premix. This lid body 5
c may have a structure that closes the hole of the outlet casting pipe 3b to which the sliding head 5 is fixed.1 For example, as shown in FIG. Something that opens and closes when force is applied is shown. The installation pipe 3, which is pivotally attached to the pipe support part 2a, is connected to a boom 6 provided on the ship body 1 with a cable 7°8.
．． The entry side casting pipe 3a is suspended via the cable 7, the intermediate casting pipe 3b is connected to the boom 6 via the cable 8, and the exit casting pipe 3C is connected to the boom 6 via the cable 9. Preferably supported and cables? , 8.9 are preferably provided with winding means (not shown) such as a winch, respectively, so that the casting pipe 3 is normally not tied to each other except during work. , 8.9, it is supported at sea.

In order to carry out the method of the present invention, first, the lower end of the sliding head 5 fixed to the tip of the casting pipe 3 of the premix casting vessel as described above is slightly buried in the seabed ground 13. In other words, the casting pipe 3 supported by the boom 6 is connected via the cables 7, 8, and 9 at sea. , 8.9, the pouring tube 3 is rotated by the weight of the pouring tube 3 and the sliding head 5 around the pivot point of the pouring tube 3 with the tube support part 2a of the support body 2, and the sliding head is rotated. 5
The lower end of the base is slightly buried in the seabed ground 13. At this time, it is preferable that the entry side casting pipe 3 is maintained supported by the boom 6 with tension acting on the cable 7, and the remaining two cables 8.9 are in a state where no tension is acting. It is loosened.

In this state, the premix in the form of a slurry is forced into the pouring pipe 3 from above the ship body 1 of the premix pouring vessel through the transfer pipe 10° flexible pipe 11 and is transferred to the sliding head 5.
The water is discharged from the lower end of the through hole 5a to the seabed ground 13. The slurry-like premix to be cast into the seabed ground 13 may be mixed either on the ship body 1 of the premix casting ship or outside the ship. The sliding head 5 is slightly buried in the surface of the discharged premix 12 discharged onto the seabed ground 13 in this way.
Position the lower end of the through hole 5 while maintaining this state.
A slurry-like premix is continuously discharged into the already discharged premix 12 from the lower end of a. Here, it is preferable that the sliding head 5 is provided with a float means 5b because the position of the lower end of the through hole 5a of the sliding head 5 can be adjusted wR.

[For production]

When the method of the present invention is carried out using a premix pouring ship suitable for carrying out the method, the sliding head 5 is not affected by the shaking of the ship body 1 caused by waves during operation.

In other words, the shaking of the ship body 1 of the premix pouring vessel caused by waves includes shaking that involves rotational movement around the longitudinal horizontal line of the ship, shaking that involves displacement in the vertical direction, and shaking that involves displacement within the horizontal plane. There is a swaying, but there is also a swaying (rolling) in which the ship body 1 rotates around the narrow center of the tube support part 2a.
If this occurs, the tube support 2a is rotatably attached to the support 2 fixed to the ship body 1, so even if the ship body 1 shakes, the tube support 2a will remain attached to the support 2. The pivoting portion of the casting pipe 3 to the pipe support portion 2a maintains a substantially horizontal state, and the shaking of the ship body 1 is not transmitted to the casting pipe 3.

In addition, if a shaking (pitching) occurs in the ship body 1 that causes the pivot point between the pipe support 2a and the casting pipe 3 to move up and down, the casting pipe 3 will move as shown in FIG. Since the casting pipe 3 can be bent around the flexible pipe joint 4 provided in the flexible pipe joint 4, the vertical movement of the sliding head 5 is prevented by the bending of the casting pipe 3 against the shaking of the ship body 1. It moves along the surface of the discharged premix 12 and/or the seabed ground 13. Furthermore, when the ship body 1 is shaken up and down, the sliding head 5 moves along the surface of the discharged premix 12 and/or the seabed ground 13, as shown in FIG. 5(A).

Furthermore, if mountain sand is mixed in the slurry-like premix at a high rate as described above, and the sliding head 5 is further provided with the float means 5b, the lower end of the sliding head 5 is connected to the discharged premix 12.
The depth to which it is buried into the surface can be adjusted.

If the through hole 5a of the sliding head 5 is provided with a lid 5c that can be opened and closed, the outlet end of the casting pipe 3 can be closed as appropriate.

〔Effect of the invention〕

As described in detail above, the method for placing a premix on the seabed according to the present invention is such that the sliding head does not move up and down even if the ship body undergoes complicated shaking due to waves, and the premix can be placed on the surface of the already discharged premix and/or the seabed ground. Since the premix discharged from the lower end of the through-hole of the sliding head does not scatter into the sea, it does not make the sea muddy, and the premix and seawater do not mix, allowing for appropriate uniaxial compression. It is possible to create high-quality artificial ground on the ocean floor that has strength, density, and low permeability.

Furthermore, even if the ship body is moved while carrying out work, the sliding head moves along the already discharged premix and/or the surface of the seabed, so the premix to be newly discharged can be continuously premixed without being scattered into the sea. This makes it possible to create high-quality artificial ground with predetermined characteristic values on the seabed.
At this time, if the pipe support is installed with its axis aligned with the direction of movement of the ship, and if the support is fixed to the rear of the ship, the cast pipe and pipe support will be damaged when the ship moves. It is possible to reduce the burden placed on the pivot joint with the other parts.

In addition, when the sliding head is provided with a float means, the depth at which the lower end of the sliding head is buried in the discharged premix and/or the surface of the seabed soil can be adjusted, so that the lower end of the sliding head is buried in the discharged premix and/or the surface of the seabed. This makes it possible to more reliably maintain the state of being slightly buried in the surface.

If the sliding head is equipped with a lid that closes the through hole, it is possible to stop the premix discharge as appropriate, so the premix discharge can be temporarily stopped when starting work, etc. As a result, the premix may be discharged before the lower end of the sliding head reaches the already discharged premix and/or the surface of the seabed or ground, or the remaining premix may be discharged at the end of the work, contaminating the seawater. There is no such thing.

The industrial value of the present invention, which has various advantages as described above and can efficiently create artificial ground while preventing mixing of the premix to be poured with seawater as much as possible, is extremely great.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a state in which a slurry-like premix is being poured into seabed ground by an embodiment of a premix pouring vessel suitable for carrying out the method of the present invention, and FIG. The third is a cross-sectional explanatory diagram of part A in the figure, the third is a cross-sectional explanatory diagram showing an example of a support body, the fourth is a cross-sectional explanatory diagram showing an example of a flexible pipe joint, and the fifth (a) and (b) are An explanatory diagram showing the displacement of the sliding head and casting pipe due to the shaking of the ship body due to sea waves, Figure 6.Sliding head and the displacement due to the movement of the ship body moving to continuously pour premix. FIG. 7 is an explanatory diagram showing the displacement of the casting pipe, and FIG. 7 is an explanatory diagram showing the state in which the premix is cast into the seabed ground. In the drawing 1... Ship body 2... Support body 2a... Pipe support part 3... Casting pipe 3a... Entry side casting pipe 3b... Intermediate casting Pipe 3c...Outlet pouring pipe 4...Flexible pipe joint 4a...Lower connecting hardware 4aa...Arm 4ab...Circle 4ac...Bin. 4b...Top connection hardware 4ba...Arm. 4bb...Pin 4c...Flexible pipe 5...Sliding head 5a...Through hole 5b...Float means 5c...Lid 5d...Cylinder 6... ... Boom 10 ... Transfer pipe 11 ... Flexible pipe 12 ... Already discharged premix 13 ... Screen bottom ground No. 4

Claims (1)

[Scope of Claims] 1. A support (2) which is rotatably pivoted with the axis of the tube support (2a) substantially horizontal and fixed on the ship body (1), and the tube support. The pipe is pivoted to the end of the section (2a) so as to be rotatable around a substantially horizontal line, and is divided into two or more parts by at least two flexible pipe joints (4) provided at intervals. A setting pipe (3) and a casting pipe (3) at the end of the casting pipe (3) on the opposite side to the pipe support part (2a) side.
The lower end of the sliding head (5) is placed in the seabed by a premix casting vessel equipped with a sliding head (5) that is fixed in such a manner that the hole in the hole and the central through hole (5a) are aligned with each other. (13
) is slightly buried in the surface of the vessel (1), and a slurry-like premix is forced into the casting pipe (3) from above the vessel body (1) and discharged from the through hole (5a) of the sliding head (5). , while keeping the lower end of the sliding head (5) slightly buried in the surface of the already discharged premix (12), the premix is continuously discharged onto the seabed ground (13). A method for placing a premix on the seabed, which is characterized by placing a premix on the seabed. 2. A support body (2) having a tube support portion (2a) which is fixed on the ship body (1) and rotatably pivoted with its axis substantially horizontal, and this tube support portion (2a). A pouring pipe that is pivoted to the end of the pipe so as to be rotatable about a substantially horizontal line and is divided into two or more parts by at least two or more flexible pipe joints (4) that are spaced apart. A through hole (5a) is drilled in the center of the pipe (3) and the casting pipe (3)
) at the end opposite to the tube support part (2a).
A premix pouring vessel characterized in that it is equipped with a sliding head (5) that is fixed in a state where the pouring head (a) and the hole of the pouring pipe (3) are aligned with each other. 3. The premix casting boat according to claim 2, wherein the sliding head (5) is provided with float means (5b) for imparting buoyancy to the sliding head (5). 4. Claim 2 or 3, wherein the through hole (5a) of the sliding head (5) is provided with a lid (5c) that can be opened and closed.
Premix pouring vessel described in . 5. The pipe support according to any one of claims 2 to 4, wherein the pipe support part (2a) is attached to the support body (2) with its axis aligned with the longitudinal direction of the ship body (1). Premix pouring vessel.