JP2000120929A - Method and device for filling space below pipe of pipe body laid on water bottom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for filling a space below the pipe of a pipe body laid on a water bottom to completely fill a gap without increasing a gap below a laid pipe body, eliminating a need for a deep recessed groove for laying a pipe body, and desides exerting the load of the pipe body by a refilling material under the pipe body and decreasing the thickness of the pipe body. SOLUTION: A refilling material 4, such as crushed stone and/or sand, is mixed with water on a ground or on a soil carriage ship 6 to produce slurry. The slurry is fed through a conveyance pipe 12 to the side of a pipe body 2 laid on a water bottom. By injecting slurry with the opening of the conveyance pipe 12 pointing toward a position below the pipe body 3 laid on a water bottom, a gap below the pipe body laid on a water bottom is filled with the refilling material 4. The refilling material 4 is charged to one side of the pipe body 2 laid on a water bottom installed in a recessed groove 1 for laying a pipe, one side of a gap below a pipe body for laying is closed, and thereafter the slurry is injected from the other side part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for laying a water bottom laying pipe laid on the sea floor, for example, for a cooling water supply / drainage channel of a thermal power plant.

[0002]

2. Description of the Related Art Conventionally, when laying a pipe of this kind on a water bottom, a ditch is excavated and formed on a seabed at a laying position by using a dredger or the like, and after performing necessary ground treatment, a supporter such as a sleeper is formed. Install a water bottom laying pipe at a distance from the groove bottom through the material,
After that, the groove is filled with a backfill material, and a pipe is buried in the water bottom.

[0003]

In such a conventional laying method, since the backfill material is dropped from the water surface to fill the groove in which the pipe is installed, the angle of repose when the backfill material is piled up. In the case where is large, a gap is formed between the surface of the backfill material dropped from both sides of the pipe and the bottom of the pipe only by dropping from the surface of the water as shown in FIG. There is a problem that a proper filling cannot be performed.

For this reason, conventionally, it is necessary to increase the distance between the bottom surface of the groove for laying the pipe and the bottom of the pipe to be installed, so that the backfill material can easily enter under the pipe. It becomes necessary to make the groove to be excavated in the water bottom deep,
There is a problem in that the cost for excavation and backfilling is increased.

[0005] However, since filling under the pipe is still not expected, the wall pressure of the pipe is increased by increasing the wall pressure of the pipe without expecting the support of the pipe by the backfill material under the pipe. Therefore, there has been a problem that the manufacturing cost of the tube is large.

The present invention has been made in view of such a conventional problem,
The gap can be completely filled without having to make the gap under the laying pipe large, and a deep concave groove for laying the pipe is not required.
An object of the present invention is to provide a method and apparatus for filling a water bottom laid pipe below a pipe, which can receive a load of the pipe by the backfill material and can reduce the wall pressure of the pipe.

[0007]

SUMMARY OF THE INVENTION In order to solve the conventional problems as described above and to achieve the intended object, a feature of the method of the present invention is that a recess is formed in a groove for pipe installation formed in a water bottom. In a method of filling a backwater laying pipe in a space under a waterfloor laying pipe installed at a distance from a groove bottom, a backfill material such as crushed stone and / or sand is placed on land or on a ship. The slurry is mixed with water to form a slurry, and the slurry is sent to the side of the submerged pipe through a transport pipe, and the slurry is injected by spraying the opening of the transport pipe downward under the pipe. The refilling material is to be filled under the water bottom laid pipe.

[0008] A backfill material is put into the groove on one side of the water-bottom laid pipe set in the pipe-laying groove to close one side of a gap below the pipe-laying pipe. Thereafter, it is preferable that the backfill material is filled under the water bottom laid pipe by spraying a slurry from the other side into a gap below the water bottom laid pipe, and a single-grained crushed stone and / or The use of sand is preferred.

[0009] The feature of the apparatus of the present invention is that crushed stone and / or
Or a storage tank containing a backfill material such as sand or the like, and pouring it into a slurry to be slurried, conveying means for transferring the slurry in the storage tank to the bottom of the water through a conveying pipe, and a tip of the conveying pipe of the conveying means. And a slurry injection nozzle that is connected to the water bottom by a weight and is installed at a water bottom by a weight, and that injects a slurry sent through a transfer pipe at a predetermined angle.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows an apparatus used in the method of the present invention. In FIG.
Is a submerged pipe installed on a pillow-shaped support member 3 at the bottom of the concave groove 1.

As an apparatus for filling the gap a between the pipes 2, an earth transport ship 6 having a storage tank 5 on which a backfill material 4 is loaded and a backfill material in the storage tank 5 are formed into a slurry to form a water bottom. And a slurry jet nozzle 8 for jetting the conveyed slurry toward the gap a under the pipe 2. In the storage tank, the loaded backfill material 4 The underwater pump 10 pumps up and injects seawater, and the transporting means 7 has a sand pump 11 and a transport pipe 12, and the sand pump 11 sucks backfill material 4 in the storage tank 5 together with water to form a slurry. Plain transfer pipe 12
I try to move inside.

The slurry injection nozzle 8 is connected to a lower end of the transport pipe 12 and is held at a predetermined position on the water bottom by a weight 13. The vertical and horizontal angles of the slurry injection port are set to a predetermined angle. Is fixed against the weight to maintain.

Next, a method of filling under a pipe using the above-described apparatus will be described.

As shown in FIG. 2, after a pipe 2 is installed via a supporting member 3 in a groove 1 formed by excavation in the water bottom, first, a bucket or the like is placed in a groove 1 on one side of the pipe 2. The backfill material 4 is charged using a normal dropping device, and one side of the gap a below the tube 2 is closed as shown in FIG. At this time, the backfilling material 4 enters the state below the tube 2 from one side at its own angle of repose α.

Next, as shown in FIG. 4, the transport pipe 12 is sunk on the opposite side of the pipe 2, the weight 13 is grounded, the injection nozzle 8 is directed toward the gap a below the pipe 2, and the sand pump 11
, The backfill material 4 is sucked together with the water, sent to the bottom of the water as a slurry, and sprayed downward from the spray nozzle 8 toward the tube body 2, and the remaining gap a is settled by the sedimentation of the backfill material 4. fill in.

After the filling of 5 to 6 m in the length direction of the tube at one position in this manner, the position of the injection nozzle 8 is further retracted by 5 to 6 m in the longitudinal direction of the tube 2, and the next filling is performed. Do.

At this time, the angle of the injection nozzle 8 is 45 degrees in the horizontal direction with respect to the axial direction of the tube 2, as shown in FIGS ^. The vertical direction is preferably horizontal or slightly upward, and the angle and the velocity of the jet are most effective for the sedimentation of the backfill material below the pipe according to the conditions such as the particle size of the backfill material and the specific gravity. Others are selected by a test at the beginning of filling so as to be carried out, and then are continuously carried out.

As the backfill material 4, various powdery and granular materials such as granulated stone, single-grained stone, coarse sand, granulated slag, granular slag, and coal ash granulated material can be used.

In this way, the lower part of the tube 2 is completely filled,
After that, the backfill material 4 is charged using a normal bucket or other normal dropping device, the inside of the groove 1 is filled, and the tube 2 is buried.

In the above-described example, the gap under the pipe 2 is closed by dropping a backfill material on one side, and then filling is performed by spraying the slurry. However, as shown in FIG. The gap filling operation may be performed only by the jetting.

EXPERIMENTAL EXAMPLE Next, an experiment using a model according to an embodiment of the present invention will be described.

1. Experimental Model The experimental model was performed on a 1/2 scale as shown in Table 1. Along with the scale of the length scale, a similarity rule is applied between actual phenomena and experimental measurements. The fluid rule is applied to the similarity rule. For this reason, not only the experimental device but also a crushed stone having a particle size １ ／ of the particle size used in the field was used.

2. Experimental equipment As shown in FIG. 6, a model steel pipe 21 of a buried pipe having a diameter of 2000 mm is installed in a water tank 20 at an interval of 250 mm from the bottom of the water, and the injection nozzle 22 is directed horizontally, and
Installed at an angle of 45 degrees with respect to the axial direction of the model steel pipe 21,
The slurry was conveyed and ejected by a sand pump 24 while being supported by a cart 23 on the water tank 20.

In the figure, 25 is a flow meter, 26 is a throttle valve,
27 is a submersible pump for supplying water.

3. Used backfill materials Used materials are granulated crushed stone (10-40mm), coarse sand, No.7 crushed stone (2.5-5mm) granulated slag, etc. Fillability, expected value of ground reaction force coefficient, coating The No. 7 crushed stone was selected based on the evaluation and judgment based on the effect.

Since the model scale was halved in the experiment, the material used had a similar particle size distribution and had a 50% particle size that was 砕 that of No. 7 crushed stone. In addition, materials equivalent to sea sand equivalents were also prepared for comparison with the conventional method.

4. Results of gap filling experiment under tube (1) Case 1 a. Method: After closing one of the lower gaps of the pipe with a pile of backfill material piled up by direct casting on one side of the steel pipe 21,
Filling by slurry injection was performed. At this time, the angle of repose of the mountain was 30 degrees. b. Materials used and slurry concentration: No. 7 crushed stone equivalent (Meisei Sand), 8% c. Flow rate and injection time: 2 (m / sec), 10 minutes d. Measurement / measurement items: filling status, filling shape, flow rate, time, water carrying amount e. Result: As shown in FIG. 7 (a), the pipe immediately below the pipe was filled, the pipe was closed, and a gap was partially formed at the foot of the hill that had been charged earlier. (2) Case 2 a. Method: After closing one of the lower gaps of the pipe with a pile of backfill material piled up by direct casting on one side of the steel pipe 21,
Filling by slurry injection was performed. At this time, the angle of repose of the mountain was 30 degrees. b. Materials used and slurry concentration: No. 7 crushed stone equivalent (Meisei Sand), 9.3% c. Flow rate and injection time: 2.5 (m / sec), 10 minutes d. Measurement / measurement items: filling status, filling shape, flow rate, time, water carrying amount e. Result: As shown in FIG. 7 (b), all of the gap immediately below the pipe and the skirt gap previously charged were filled. (3) Case 3 a. Method: Filling by slurry injection was performed in a state where both sides of the lower gap of the pipe were opened. b. Material used and slurry concentration: No. 7 crushed stone equivalent (Meisei Sand), 9.6% c. Flow rate and injection time: 2.5 (m / sec), 14 minutes d. Measurement / measurement items: filling status, filling shape, flow rate, time, water carrying amount e. Result: As shown in FIG. 7 (c), the amount of soil to be sent was large, so that the filling immediately below the pipe was quick, and some voids remained on the opposite side of the discharge port. (4) Case 4 a. Method: Backfilling was performed only by dropping as in the conventional method. b. Materials used: No. 7 crushed stone equivalent (Meisei Sand) c. Measurement / measurement items: filling status, filling shape d. Result: As shown in FIG. 8, in both cases, the mountains on both sides entered the steel pipe at a repose angle by themselves, but a gap remained just below the pipe. (5) Case 5 a. Method: Backfilling was performed only by dropping as in the conventional method. b. Materials used: Sea sand equivalent (grain-conditioned) c. Measurement / measurement items: filling status, filling shape d. Result: As shown in FIG. 8, in both cases, the mountains on both sides entered the steel pipe at a repose angle by themselves, but a gap remained just below the pipe.

[0029]

As described above, in the present invention, underfilling of a pipe is performed by pouring water into a backfill material such as crushed stone, transporting the slurry, and injecting the slurry toward a gap below the laid pipe by an injection nozzle. By doing so, even if the space under the laid pipe is small, the space is densely filled, so that the concave groove formed in the water bottom can be made shallower than the conventional one, and the weight of the pipe is reduced. Can be supported by the backfill material, so that a tube having a smaller wall thickness can be used as compared with the related art, and the cost can be greatly reduced.

When filling, a backfill material is put into the groove on one side of the submerged pipe installed in the groove for pipe installation to fill one side of the gap below the pipe for installation. Closed,
Thereafter, the slurry is sprayed from the other side into the gap under the submerged pipe to fill the backfill material under the submerged pipe, so that a complete filling operation can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view schematically showing an apparatus used in the method of the present invention.

FIG. 2 is a cross-sectional view of a state before a backfill material is carried in a construction step of the method of the present invention.

FIG. 3 is a cross-sectional view showing a closed state on one side of the gap due to the insertion of the backfill material.

FIG. 4 is a cross-sectional view showing a filling state by slurry injection according to the first embodiment.

FIG. 5 is a plan view of the same.

FIG. 6 is a sectional view showing an experimental facility of the present invention.

FIGS. 7A to 7C are cross-sectional views showing experimental results obtained by the method of the present invention.

FIG. 8 is a cross-sectional view showing an experimental result by a conventional method.

[Explanation of symbols]

 a Clearance 1 Groove for pipe installation 2 Water-bottom installation pipe 3 Support material 4 Backfill material 5 Storage tank 6 Earth transport vessel 7 Transport means 8 Slurry injection nozzle 10 Submersible pump 11 Sand pump 12 Transport pipe 13 Weight 20 Water tank 21 Model steel pipe 22 Injection nozzle 23 Bogie 24 Sand pump 25 Current meter 26 Squeeze valve 27 Submersible pump

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Jiro Haro 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Inside Shikoku Electric Power Company (72) Inventor Shigehiro Ozaki 2-5 Marunouchi, Takamatsu City, Kagawa Prefecture Shikoku Electric Power Company Inside the company (72) Inventor Shinobu Yamazaki 1007-3 Murie-cho, Kida-gun, Kagawa Prefecture Inside Shiden Technical Consultant Co., Ltd. (72) Inventor Yoshitaka Otani 4-4-3 Chifuna-cho, Matsuyama-shi, Ehime Prefecture Inside the branch (72) Inventor Sadao Tashita 4-4-3 Chifuna-cho, Matsuyama-shi, Ehime Prefecture Goyo Construction Inside the Shikoku Branch Co., Ltd. Shikoku branch office

Claims (4)

[Claims] 1. An underwater pipe laying pipe for filling backfill material into a pipe laying groove formed in a water bottom excavated and formed at a distance from the bottom of the groove. In the filling method, a backfill material such as crushed stone and / or sand is mixed with water on land or on a ship to form a slurry, and the slurry is sent to a side portion of the submerged pipe through a transport pipe, and the A method of filling a submerged pipe below a pipe, characterized in that the backfill material is filled under the pipe, by spraying the slurry with an opening directed below the pipe. 2. A backfill material is injected into the groove on one side of the water-bottom laid pipe installed in the pipe-laying groove to close one side of a gap below the laying pipe. 2. The method according to claim 1, wherein the backfill material is filled under the underwater pipe by spraying a slurry from the other side into a gap under the underwater pipe. 3. The method according to claim 1, wherein the backfill material is a single-grain crushed stone or sand. 4. A storage tank for storing a backfill material such as crushed stone and / or sand and pouring it into a slurry, and means for transferring the slurry in the storage tank to a water bottom through a transfer pipe;
A pipe of a water bottom installation pipe body, comprising: a slurry injection nozzle connected to a tip portion of the transfer pipe of the transfer means, installed on a water bottom by a weight, and spraying a slurry sent through the transfer pipe at a predetermined angle. Under filling device.