JPH0514834B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention particularly relates to a method for constructing intake and drainage pipes for large-diameter long steel pipes.

[Prior Art] The conventional method of laying intake and drainage pipes on the seabed involves attaching floats to the pipes in order to adjust the buoyancy of the pipes. When using this construction method to lay small-diameter pipes in shallow water, the pressure resistance of the floats was low and the number required was small, so this was not a problem. However, for example, when installing large-diameter long steel pipes in the deep sea for ocean thermal power generation, the pressure resistance of the floats is high, and the number of floats required is large, which poses a problem. Have difficulty.

Also, if one intake and drainage pipe is laid on the seabed,
Previously, pipes were buried because the ground beneath them was scoured by ocean currents. However, it is impossible to bury it in deep sea, and other measures to prevent scouring are required.

In general, various techniques for laying pipes on the seabed are known. For example, Japanese Patent Application Laid-Open No. 73283/1983 discloses a technique for laying a large diameter pipe using a float pipe and a large diameter pipe. However, with such known techniques, it is not possible to stretch and lay long pipes over long distances.

Further, Japanese Patent Application Laid-Open No. 57-54790 discloses a technique in which two pipes are connected, and the pipes are set in advance on the water and then submerged. However, even with this known technology, when installing over a long distance, the work is extremely troublesome.

Furthermore, Japanese Patent Application Laid-Open No. 156581/1983 discloses a technique for laying pipes by towing them by ship, but it is still difficult to lay them over long distances.

[Problems to be Solved] Therefore, an object of the present invention is to provide an intake and drainage pipe lead-in construction method that allows pipes to be laid on the seabed over long distances while adding pipes on land.

[Means for Solving the Problems] According to the intake and drainage pipe lead-in construction method of the present invention, an anchor and a sinker are sunk in advance on the seabed, three pipes are loosely wound with wire in a triangular shape, and one of the pipes is One or two of these pipes are used as floating pipes, and chains are suspended along both sides of these pipes.
The lead-in wire attached to the main pipe is wound around the winch on land via the anchor, the floating pipe is closed with a lid, and the three pipes are launched by pulling the lead-in wire. The pipes are added one after another and pulled into the designated position, then the lid is removed and water is poured into the floating pipes, allowing the three pipes to land on the seabed.

[Description of Effects] Therefore, the three tubes are pulled in a floating state without landing on the bottom, so there is no friction with the seabed and they can be easily pulled to a predetermined position. These pipes can be added one after another on land, and there is no need for dangerous work at sea or on the seabed, which is safe.

In addition, a set of three pipes is less susceptible to scouring than a single pipe, and in addition, a chain can be installed to adjust the buoyancy. It can act as a weight to stabilize the landing of the intake and drainage pipes on the seabed.

Furthermore, all three pipes can be used as intake and drainage pipes after they are installed, and the floating pipes are easy to work with, simply by removing the lids.

[Preferred Embodiment] When carrying out the present invention, when one of the three pipes is a floating pipe, the arrangement is such that if the seabed is concave, the floating pipe is placed three times above the lower pipe. Arranged in a square shape, loosely wrapped with wire to support freely,
If the seabed is flat, wrap the wire in the same arrangement as above and tie it tightly; if the sea surface is convex, arrange it in a row with the floating tube in the center and wrap the wire tightly. Preferably tied down. In this way,
It is possible to improve the durability of flexible and durable floating tubes by relieving stress.

When carrying out the present invention, the chain is suspended with the required pitch and slack, and these pitch and slack mean that when the intake and drainage pipe is pulled in, the lower part of the chain touches the seabed and the intake and drainage pipe is raised to a predetermined height above the seabed. It is preferable to set it so that it floats in the air. In this way, the drawing of the intake and drainage pipes can be stabilized and smoothed.

[Examples] Examples of the present invention will be described below with reference to the drawings.

First, as shown in FIG. 1, a required number of anchors 1 are attached to a concrete sinker 2, and a pulling wire 4 passed through a pulley 3 provided at the upper end of the sinker 2 is connected to a tugboat and a barge 5 (not shown). Support, submarine G
Anchor 1 and sinker 2 are sunk into predetermined positions (FIG. 2, section I).

Next, as shown in FIG.
One end 4a is attached to a winch on land (not shown), and the other end 4b is connected to the tip of a pipe set A (water intake pipe in the illustrated example) formed of three pipes 6, 7, and 8.

As shown in FIG. 3, the water intake pipe A is formed into a triangular shape and is loosely wound with a wire 9. The lower two pipes 6 and 7 are ordinary steel pipes, but the upper pipe 8 is a floating pipe and is a pressure-resistant pipe, and a lid 10 is bolted to the spout 8a. A float 12 is connected to 10 via a wire 11.
is installed. Further, on both sides of the lower pipes 6 and 7, a chain 13 for adjusting the total buoyancy of the water intake pipe A together with a pipe 8 which is a floating body pipe is suspended along both sides at a predetermined pitch and slack. The pitch and slack of the chain 13 are determined so that when the chain 13 is pulled in, the lower part of the chain 13 contacts the seabed G and the water intake pipe A is suspended at a predetermined height above the seabed G, as shown in FIG. Incidentally, the pipes 6 and 7 are also provided with spouts 6a and 7a, respectively, as shown in FIG.

First, after the pipe 8 is water-tightened with the lid 10, the winch is operated and the lead-in wire 4 is pulled to launch the tip of the water intake pipe A into the water. Then, when the water depth at the tip reaches approximately 30 m, the bolt of the lid 10 is removed by a diver. At this water depth, the lid 10
is pressed into close contact with the spout 8a of the tube 8 and cannot be removed.

Furthermore, while adding the pipes 6, 7, and 8, pull the drawing wire 4 with a winch to draw the water intake pipe A to a predetermined position, and then gradually pour water from the upper end of the pipe 8 to eliminate the buoyancy of the pipe 8 and remove it. Gradually let water tube A reach the bottom. When the water injection into the pipe 8 is completed, the internal and external pressures of the lid 10 become equal and the external pressure disappears, so the float 12 is lifted up by a crane (not shown), the lid 10 is removed, and the installation is completed. In addition, when pulling in,
A wire 14 is attached to the tip of the water intake pipe A, and wires (not shown) are attached to several points in the middle, and supported by a small tugboat (not shown) to assist in pulling in the water intake pipe A and correct lateral flow, and to improve the long-term operation of the large tugboat. Sea towing can be made unnecessary.

Since the pipe 8 is used as a floating pipe in this way, there is no need for a separate float in conventional construction methods.
Therefore, all problems related to conventional floats such as pressure resistance, number of floats, and removal after installation can be solved.

In addition, as shown in FIGS. 4 to 8, when the intake pipe A is on the bottom of the seabed G, the lower two pipes 6 and 7 increase the bottom area of the intake pipe A, and
Since the chains 13, 13 block the ocean current, they prevent scouring caused by the ocean current, and furthermore, the chains 13, 13 serve as weights to stabilize the water intake pipe A on the seabed G.

The arrangement of the tubes 6, 7, and 8 shown in FIG. 6 is suitable for cases in which the tube 8, which is a pressure-resistant tube with poor flexibility, is wound with a wire 9 and freely supported above the tubes 6, 7, and is concave. It is.

On the other hand, if the seabed G is flat, the seventh
As shown in the figure, connect the three tubes 6, 7, 8 to the wire 9.
If the seabed G is convex, it is preferable to secure the pipes 6, 6,
It is preferable to arrange the wires 8 and 7 in parallel and secure them with a wire 9. In this way, the arrangement of the pipes 6, 7, and 8 can be determined depending on the situation on the seabed G, and the stress on the pipe 8, which is a pressure-resistant pipe with poor flexibility in the upper or central part, can be alleviated and its durability can be improved. .

[Effects of the Invention] As described above, according to the present invention, the following excellent effects are achieved.

(i) Since the three pipes are pulled without touching the bottom, there is no friction with the seabed, and the pipes can be easily added to the specified position using a winch on land.

(ii) Chains can adjust buoyancy and prevent scouring by ocean currents.

(iii) It is safe as there is no work to be done at sea or on the seabed.

(iv) Landing on the bottom can be as simple as removing the lid.

(v) Work is not affected by seabed conditions and work efficiency is high.

[Brief explanation of the drawing]

Figure 1 is a side view illustrating the condition of the anchor being sunk;
Figure 2 is a side view illustrating the state in which the intake pipe is drawn in, Figure 3 is an orthogonal sectional view of Figure 2, Figure 4 is a side view showing the state when the intake pipe has been laid, and Figure 5 is the same as Figure 4. The front view of the spout, FIG. 6, FIG. 7, and FIG. 8 are orthogonal cross-sectional views showing the arrangement of three different pipes when the spout reaches the bottom. A... Water intake pipe, G... Seabed, 1... Anchor, 2
... Sinker, 4 ... Leading wire, 6, 7, 8
...Tube, 9...Wire, 10...Lid, 12...Float, 13...Chain.

Claims (1)

[Claims] 1. Anchors and sinkers are sunk in advance on the seabed, three pipes are loosely wound with wire in a triangular shape, one or two of these pipes are made into floating pipes, and the wire is placed along both sides of these pipes. While suspending the chain, the pulling wire attached to one pipe is wound around the winch on land via the anchor, the floating tube is closed with a lid, and the pulling wire is pulled.
It is characterized by launching three tubes, successively adding the three tubes and drawing them to a predetermined position, then removing the lid and injecting water into the floating tubes so that the three tubes land on the seabed. Intake and drainage pipe installation method.