JPS6255366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for protecting long bodies installed on the seabed, such as submarine cables and water pipes.

The main causes of injury to long bodies laid on the seabed were anchors and fishing gear.

Conventionally, long bodies laid on the seabed have been protected by burying the long body 2 below the seabed surface 3 using a burying machine 1 as shown in Figure 1; A construction method in which a concrete block 4 is placed over the long body 2 laid on the top to protect it, or as shown in FIG. After laying the concrete 6 on a laying ship at sea, a concrete 6 made by mixing aggregate (sand, gravel, etc.) with cement is poured into the groove 5 through a transport pipe, and the elongated body 2 is protected with the concrete 6. It had been taken.

However, the protection construction method shown in FIG. 1 has the disadvantage that the seabed surface 3 is washed by tidal currents and the burial depth becomes shallower over time, making it easier to cause external injuries.

The protection construction method shown in Fig. 2 can sufficiently withstand a direct hit from an anchor, but has the disadvantage that it has no protective effect against lateral forces.

The protection construction method shown in FIG.
It is necessary to sequentially pour concrete 6 onto the inner long body 2 from a laying ship on the sea, which is disadvantageous in that it is time-consuming and takes a long time. Furthermore, the construction method of pouring concrete 6 into the groove 5 requires a large amount of concrete materials such as aggregate to be supplied from the sea, which has the disadvantage of extremely high construction costs.

Furthermore, this construction method has the disadvantage that it requires a large ship, since it is necessary to load extremely heavy and bulky aggregates such as gravel and sand onto a ship at sea.

The object of the present invention is to provide a long body laid on the seabed that can sufficiently protect a long body buried in the seabed, requires less effort and construction period than concrete protection method, and can be constructed at low cost. To provide protective construction methods.

Hereinafter, specific examples of the present invention will be explained in detail with reference to FIGS. 4 to 7. In this embodiment, the elongated body 2 is laid on the seabed surface 3 in advance, and then the elongated body 2 is
This figure shows an example in which the present invention is applied to the so-called post-burying method of burying in the seabed.

4 and 5 show an example of a jet-type burying machine 7 used in the construction method of the present invention.
This jet-type burial machine 7 is equipped with a plurality of jet nozzles 9, 9, .
A pair of submersible pumps 10, 10 are mounted on B to send pressurized seawater to each jet nozzle 9, 9, . . . . A guide path 11 is formed in the central frame 8A of the body 8 to guide the elongated body into the groove dug by the jet nozzles 9, 9, . . . of the burial machine 7. A hardening agent collection tank 12 is mounted on the central frame 8A of the fuselage 8, which stores liquid hardening agent sent from the sea.
Below that, there are upper and lower multi-stage jet nozzles 13A, 13A, which are located at the rear end of the fuselage 8 and spray liquid curing agent backwards.
A curing agent jetting head 13 is provided to jet the curing agent from.

FIGS. 6 and 7 show a specific example of the method of protecting a long body laid on the seabed according to this embodiment, which is carried out using the jet-type burying machine 7 as described above. In this construction method, a work boat 15 is floated on the sea surface 14, and a generator 16 and a curing agent pumping device 17 driven by power supplied from the generator 16 are installed on the work boat 15.
It is equipped with.

The work boat 15 tows the jet-type burial machine 7 via a tow rope 18. A transmission cable and a pipe 19 are attached to the towline 18 for transmitting power to the submersible pump 10 of the jet-type burying machine 7 and for sending the hardening agent to the hardening agent collection tank 12.

In such a state, the jet burying machine 7 is moved along the soft seabed surface 3 made of sand or the like by being towed by the work boat 15, and the excavation jet nozzle 9,
When waterjet is ejected from 9..., the jet-type burial machine 7 digs into the seabed and the 7th
Dig a trench 5 as shown in the figure. In this case, the inside of the trench 5 immediately after the jet-type burying machine 7 has passed has a soft form due to the sand etc. dug by the water jet flying up and mixing with seawater. The elongated body 2 is guided and laid in the groove 5 in such a state, and a hardening agent is jetted into the groove 5 from the hardening agent jetting head 13. When the elongated body 2 is installed in the groove 5, the elongated body 2 sinks across the soft ground due to its own weight and lands near the bottom of the groove 5, and the soft ground covers the elongated body 2. The hardening agent mixes with the soft ground that is in the groove 5 and covers the elongated body 2, and after a predetermined period of time becomes a hardened ground 20 as shown in FIG. 7, and the elongated body 2 is protected.

As the hardening agent, for example, cement or a so-called soil conditioner is used.

FIG. 8 shows an example in which the present invention is applied to a simultaneous burying method in which laying and burying a long body are performed at the same time. In this case, the elongated body 2 is sent out from the laying ship 21 toward the jet-type burying machine 7 on the seabed,
The jet type burying machine 7 lays the cable on the seabed and buries it at the same time. During burying, as described above, the curing agent is ejected from the curing agent injection head 13 of the jet-type embedding machine 7, and the elongated body 2 is placed in the groove 5 as shown in FIG.
The soft ground covering the groove 5 is hardened to protect the elongated body 2 within the groove 5. The work boat 15 is towed by a laying boat 21.

In the above embodiment of the present invention, a jet type burying machine is used as the burying machine, but a plow type burying machine may also be used. Earth and sand excavated by a plow-type burial machine also mixes with seawater and becomes soft, so a hardening agent can be supplied into the ground to quickly harden the ground. In addition, when a trench is formed using a plow-type burying machine, the mounds of earth and sand on both sides of the trench at the rear of the burying machine are dropped into the trench using a backfill tool attached to the rear of the burying machine.
By supplying a curing agent to that portion, the elongated body can be more reliably protected.

As explained above, in the method for protecting long seabed bodies according to the present invention, the soft ground that is generated in the trench by excavating a trench with a burying machine and covering the long body to be buried under the seabed surface is made of aggregate. Since it is used as
The aggregate is dispersed in the trench due to the impact force caused by trench excavation and is sufficiently mixed with the hardening agent, increasing the strength of the hardened ground and making it possible to maintain the long body for a long period of time. can be protected against.

Furthermore, since the hardened ground is buried beneath the seabed, it is possible to avoid getting caught by ship's anchors, fishing gear, etc. as much as possible.

Further, according to the present invention, there is an advantage that there is no need to install the formwork on the seabed surface.

In particular, in the present invention, the soft ground created within the trench by trench excavation is used as aggregate, and a hardening agent is supplied into it to harden the ground within the trench. No need to supply aggregate,
It is now necessary to simply supply the curing agent, which eliminates the need to purchase and transport aggregate, reducing construction costs.Also, supplying the curing agent from the sea is smooth because it does not contain aggregate, reducing construction time. Can be shortened.

Furthermore, according to the present invention, there is no need to load heavy and bulky aggregates onto the ship, so the work can be carried out using a smaller ship than in the past, which also reduces construction costs. can be achieved.

Moreover, in the present invention, the burying process and the protection process can be performed simultaneously, so the construction period can be shortened compared to the conventional concrete protection method.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory views showing three examples of conventional protection construction methods, and Figures 4 and 5 are side views and illustrations of one embodiment of a jet-type burying machine used in the construction method of the present invention, respectively. The back view, FIG. 6 is an explanatory diagram showing an example of the implementation state of the construction method of the present invention, and FIG. 7 is A of FIG. 6.
-A' line sectional view and FIG. 8 are explanatory diagrams showing another implementation state of the construction method of the present invention. 2... Long body, 3... Seabed surface, 5... Groove, 7...
...Jet type burial machine, 12...Curing agent collecting tank, 13...Curing agent spouting head, 14...Sea surface,
15... Work boat, 17... Curing agent pressure feeding device, 20
...hardened ground.

Claims (1)

[Claims] 1. While digging a trench in the seabed with a burying machine, a long body is laid in the trench, and the soft ground that is generated in the trench and covers the long body by the digging of the trench by the burying machine is used as aggregate. A method for protecting long bodies laid on the seabed, characterized in that the soil in the trench is hardened by supplying a curing agent that does not contain aggregate into the soft ground.