JPH0143192B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of laying a pipeline using the submarine towing method.

(Conventional technology) Conventionally, when laying a submarine pipeline,
If the length of the installation is long, the lay barge method has been used to enable construction even under severe sea conditions.

(Problem to be solved by the invention) However, when a pipeline is laid in a place where the slope of the seabed is relatively steeper than on land and extends into the deep sea,
When installing pipelines that take in water from the seabed at a depth of about 200 to 1000 meters, it is difficult to install them using the floating towing method, let alone the lay barge method, in places where there are severe waves, currents, and breaking waves at sea and on the coast.
It is appropriate to use the submarine towing method. Even with this towing method, if the wave breaking force on the coastline is large at all times (during pipeline construction), construction is difficult due to oscillations when the pipe is towed out and when the pipe is fixed.

The purpose of the present invention is to enable safe pipeline construction without causing any turbulence when the pipeline is towed out.
The purpose is to enable efficient pipeline construction.

(Means for Solving the Problems) The submarine pipeline installation method of the present invention includes the steps of excavating an oblique hole from land to reach the seabed at a depth where diving work can be performed, and after excavation, installing a diagonal hole on a gantry on land. Multiple pipe bodies are connected by a flexible joint in which the outer periphery of the joint is covered with a sliding body that doubles as a weight and has a barrel-like appearance, and when connecting the pipe bodies, the outer periphery of the joint , the step of gradually inserting the pipeline into the diagonal hole by attaching a sliding body with a barrel-like appearance that also serves as a weight covering the joint and gradually inserting the pipeline into the diagonal hole; At the point when the pipeline passes through the outlet of the oblique hole, there is a step of attaching a water intake pipe and a towing wire to the tip of the pipeline, and a step of pulling out the pipeline from the oblique hole via the towing wire with a towing boat along the seabed. This process includes the process of guiding and towing the pipeline and laying it on the seabed.

(Example) An example of the present invention will be described below based on the drawings.

As shown in Figures 1 and 2, first, a point 3 on the land area 2 is located at a distance from the coastline 1 where there is no construction failure due to breaking waves, for example, approximately 20 to 30 meters horizontally to the land side.
An oblique hole 3 is drilled from a to the seabed.

The angle of inclination of the diagonal hole 3 is set according to the seabed topography, but the exit 3b at one end of the diagonal hole should be set at a depth of approximately 20 to 200 m where there is no obstacle to diving operations due to breaking waves near the coast.
Reaching the seabed 4 over 30m. The diameter of the oblique hole 3 is approximately 1.5 times the diameter of the pipe body 5a of the pipeline 5. When drilling oblique hole 3, land part 2
A gantry 6 is installed in advance and used.

After drilling the diagonal hole, the pipe body 5 is placed on the gantry 6.
a, . . . are connected via flexible joints 7, .
, and gradually insert it into the diagonal hole 3 from the diagonal passage 9a of this slide.

When connecting the pipeline bodies 5a, . . . , a submarine towing guidance sliding body 10, .

The joint 7 is constructed of a bellows as shown in FIG. 3, and collars 7a and 7b provided on the outer periphery of both ends are joined to collars 11a and 11b at one end of the pipe bodies 5a ₁ and 5a ₂ , and this joint portion Nuts 13 at both ends of a plurality of threaded rods 12 arranged in the axial direction of the pipe,
By holding the pipe body 5a ₁ , 5
A ₂ is connected. The joint 7 is a tension joint that regulates the tensile force in the direction of the arrow with nuts 13, . . . . The sliding body 10 has one end held by a support portion 14 of the pipe main body _5a1 .
The sliding body 10 has a barrel-like appearance so that the pipeline 5 can be smoothly inserted into the diagonal hole 3 and smoothly guided along the seabed surface.

When the pipeline 5 passes through the diagonal hole 3 and its tip passes through the diagonal hole outlet 3b, a water intake pipe 15 and a submarine towing wire 16 are attached to the tip by diving.

Thereafter, the towing boat 17 pulls out the pipeline 5 from the diagonal hole 3 via the wire 16 and guides it towed along the seabed surface 4a, while at the same time, the gantry 6 of the land section 2 connects the pipeline and tilts it. It is inserted through the hole entrance 3a.

Then, the pipeline 5 is laid on a predetermined seabed surface 4a.

When guiding and towing the pipeline 5 along the seabed surface 4a, since the sliding body 10 slides on the seabed surface, the guidance can be performed smoothly and damage to the pipeline joint can be prevented.

(Effects of the Invention) As explained above, according to the present invention, a flexible joint is used for the joint portion of the pipeline, and the pipeline is inserted into the diagonal hole by covering the outer periphery of the joint with a sliding body that also serves as a weight. Since this is a method of laying the pipeline on the seabed by sliding it, the pipeline slides smoothly inside the diagonal hole and on the seabed surface, making construction efficient and smooth. Damage can be prevented. In addition, even under severe conditions such as waves, currents, and breaking waves at sea and on the coast, the pipeline can be safely operated without shaking when the pipeline is pulled out by using the trestle and diagonal hole on the land side of the pipeline. Construction is now possible.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams showing the construction state of the pipeline, respectively, and FIG. 3 is a partially cutaway front view of the joint and the sliding body. 2...land part, 3...diagonal hole, 3a...diagonal hole inlet, 3b...diagonal hole outlet, 4...undersea part, 5...pipeline, 5a, 5a ₁ , 5a ₂ ...pipe body,
6...Gandle, 7...Joint, 10...Sliding body, 15
... Water intake pipe, 16 ... Wire, 17 ... Towing boat.

Claims (1)

[Scope of Claims] 1. A step of excavating an oblique hole from land to reach the seabed at a depth where diving work can be carried out, and after the excavation, connecting a plurality of pipe bodies with flexible joints on a gantry on land to create pipes. a step of gradually inserting the pipeline into the diagonal hole while forming a line; and when the tip of the pipeline passes the outlet of the diagonal hole, a water intake pipe and a towing wire are inserted into the tip of the pipeline; and a step of laying the pipeline on the seabed by pulling out the pipeline from the diagonal hole via the towing wire with a towing vessel and guiding it along the seabed, and laying the pipeline on the seabed. A method of laying a submarine pipeline, which is characterized in that, when connecting, a sliding body having a barrel-like appearance and serving as a weight covering the joint is attached to the outer periphery of the joint.