JPS6340897B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a submarine cable burying machine, and more particularly to a submarine cable burying machine that continuously excavates a burial trench and lays a submarine cable in the trench.

[Conventional technology]

The seabed soil has soft, sandy, and hard soil (N value is 5).
~10), hard clay (N value is around 20), bedrock, etc. A machine for burying a submarine cable while excavating a trench in the submarine ground using jet water is disclosed in Japanese Utility Model Publication No. 47-19599. In this case, the burying groove is constructed such that a jet nozzle is provided on the lower surface of the sled-shaped burying machine body, a plow is swingably attached behind the jet nozzle, and the plow is moved up and down by a cylinder. When the plow encounters rock or the like, it is pushed up into the burial machine body by the action of the cylinder.

[Problem that the invention seeks to solve]

The above publication does not specifically disclose switching of the water pressure supplied to the jet nozzle. However, as mentioned above, the soil quality of the submarine ground varies.
In general, soft and sandy soils can be blown away by washing with low-pressure water of about 20 kg/ ^cm2 , but in the case of viscous soils and the N value exceeds 10, the above-mentioned low-pressure water can blow away the ground. You can't blow it away.

Therefore, if it is decided to use high pressure jet water in consideration of the case where the N value is high, there is a problem that the high pressure jet water cannot effectively blow away soft soil because the amount of water is small.

For this reason, it may be possible to investigate the soil quality of the seabed in advance and switch between low-pressure water and high-pressure water depending on the ever-changing soil quality, but this is not practical.

Therefore, an object of the present invention is to provide a burying machine that detects the resistance applied to the plow and automatically switches between low-pressure water and high-pressure water.

[Means for solving problems]

In order to solve the above problems, the present invention provides a submarine cable burying machine in which a plow is swingably attached to the main body of the burying machine and is supported by a hydraulic cylinder. Two systems of high-pressure jet water systems are provided, and one of the two systems is switched to operate according to the detection result of a back pressure detection device provided in the hydraulic cylinder.

[Effect]

The low pressure jet water system is operated while the back pressure of the hydraulic cylinder is low, and when the back pressure rises above a certain level, the system switches to the high pressure jet water system. When the back pressure becomes low again, switch to the low pressure jet water system.

〔Example〕

FIG. 1 shows a burying machine 10 and a work barge 11. The main body 12 of the burying machine 10 is made up of left and right sled parts 13 connected together by connecting shafts 14, 14', etc., and each sled part 13 is equipped with a ballast tank 15.
, and three continuous groove excavators, ie, plows 16, are swingably attached to the connecting shaft 14'.
Each plow 16 is supported by a correspondingly provided hydraulic cylinder 17 so as to be able to swing vertically. Further, a cable guide tub 18 is provided at the open upper end of each plow 16, and a cable guide pipe 19 is introduced into each tub 18. Further, an underwater pump 20 for generating low-pressure water for drilling is provided above the balance tank 15.

Although the illustrated burying device is shown for the case where three cables a are buried, it is constructed in substantially the same way when a smaller number or more cables are buried.

The work barge 11 has a towing function, and installs the drum 21 of the cable a to be buried on the ship,
It is equipped with a generating device for high pressure water, pressurized air, pressurized oil, etc., and a power generating device, and is towed by a wire rope 22 stretched between the burial machine and a cable guide tube 23 attached to the wire rope 22. The cable a is fed into the embedding machine 10 through the cable. Moreover, various hoses 24 and cables 25 are stretched between the work barge 11 and the burial machine 10, and high pressure water, pressurized air, pressurized oil, etc. necessary for excavation are supplied from the work barge 11 to the burial machine. 10, and control signals can be sent and received between the two.

The plow 16 of the burial machine 10 has a casing 26 whose longitudinal sides of left and right sides are joined by a top plate and whose side facing the ground b is open.
6, a cable passage 27, two ejector ducts 28, 28', and a group of low-pressure water nozzles 29 as an excavation part are installed in the upper part of the open surface of the casing 26.
Further, a group of high pressure water nozzles 30 are arranged at the bottom thereof.

The ejector ducts 28, 28' are connected to the lower part of the low pressure water nozzle group 29 and the high pressure water nozzle 3.
The ejector ducts 28 and 28' are connected to ejector ducts 31 and 32 provided at the bottom of group 0, respectively, and the ejector ducts 28 and 28' are connected to an earth discharge pipe 33 shown in FIG.

Furthermore, hydraulic oil passages 34 and 34' are connected to the front and rear ports of the hydraulic cylinder 17, and are operated by an electromagnetic switching valve 35. Further, the passages 34 and 34' are communicated by a passage 38 via a relief valve 36 and a check valve 37, and a pressure gauge 39 for back pressure is connected thereto.

The low-pressure water nozzle 29 is connected to a low-pressure jet water system 29' that includes a subsea pump 20 as a low-pressure water source and a pressurized air source 40 on the work barge 11, as shown in FIG. Pressurized air is supplied to the injection portion of the low pressure water nozzle 29 to prevent cavitation. Further, the high pressure water nozzle 30 is connected to a high pressure jet water system 3 that includes a high pressure water generation source 41, a pressurized air generation source 40, and a subsea pump 20 that is a low pressure water generation source.
0', and the high pressure jet water is surrounded and protected by the low pressure jet water. Further, each ejector 31, 32 is also supplied with high pressure water and low pressure water.

Switching between the low pressure jet water system 29' and the high pressure jet water system 30' is performed by the back pressure detection device 43 of the hydraulic cylinder 17. This detection device 43
is operated at a pressure lower than the operating pressure of the relief valve 36, and when the back pressure detection device 43 operates at a predetermined pressure while low pressure jet water is being supplied to the low pressure jet water system 29', the high pressure jet water system 30 is activated. ′
Switch to.

Since the burying machine according to the embodiment of the present invention is constructed as described above, the burying machine 10 is tilted at an angle along the ground b by the hydraulic cylinder 17, and the burying machine 10 is towed by the work barge 11. water nozzle 2
Jet water is injected from the ejector 9 or the high-pressure water nozzle 30, and as necessary, the high-pressure water nozzle 30 is moved up and down by the hydraulic cylinder 42 (see Fig. 2) to excavate a cable burial trench of the required width.
The earth and sand sucked in from 1 and 32 are discharged from the earth discharge pipe 33, and the cable a is buried in the burial trench.

In this case, if the soil has a low N value such as soft soil or sand, the low pressure jet water system 29' is activated and low pressure jet water is injected from the low pressure water nozzle 29. Furthermore, when soil with a high N value such as hard soil or hard viscous soil is encountered, the resistance acting on the plow 16 becomes large, so the back pressure detection device 43 is activated and the high pressure jet water system 3
0', and high pressure jet water is injected from the high pressure water nozzle 30.

Furthermore, when the plow 16 encounters a bedrock c etc., the back pressure in the hydraulic cylinder 17 further increases, so the relief valve 36 operates and the hydraulic oil moves, reducing the hydraulic pressure in the passage 38, check valve 37, and passage 34'. A circuit is formed and the hydraulic cylinder 17 is actuated, causing the plow 16 to flip upward. Therefore, it is possible to cross over bedrock c etc.

Since the pressure decreases after going over bedrock c etc., the pressure is detected by the pressure gauge 39, the switching valve 35 is activated by an appropriate means, the plow 16 is lowered again, and the plow 16 is supported at the required digging angle. do.

Note that when a plurality of plows 16 are provided, the above-mentioned control can be performed independently for each plow 16.

〔Effect of the invention〕

As described above, the present invention enables the use of a low-pressure jet water system and a high-pressure jet water system to be automatically switched depending on the magnitude of the resistance acting on the plow. Water has the effect of enabling more efficient excavation.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the burying machine and the work barge in a working state, FIG. 2 is a sectional view of the plow portion and a hydraulic circuit diagram, and FIG. 3 is a control circuit diagram. 10... Burying machine, 11... Work barge, 16... Plow, 1
7...Hydraulic cylinder, 20...Sea pump, 29...Low pressure water nozzle, 29'...Low pressure jet water system, 30...
High pressure water nozzle, 34, 34'... passage, 35... electromagnetic switching valve, 36... relief valve, 37... check valve, 3
9', 40... Pressurized air generation source, 41... High pressure water generation source, 43... Back pressure detection device.

Claims (1)

[Claims] 1. In a submarine cable burying machine in which a plow is swingably attached to the burying machine body and supported by a hydraulic cylinder, the plow is equipped with two systems: a low-pressure jet water system having a low-pressure jet nozzle, and a high-pressure jet water system having a high-pressure jet nozzle, and the above-mentioned A submarine cable burying machine characterized in that one of the two systems described above is switched to operate based on the detection result of a back pressure detection device provided in a hydraulic cylinder.