WO1997034128A1

WO1997034128A1 - Method of submarine crustal survey

Info

Publication number: WO1997034128A1
Application number: PCT/JP1997/000781
Authority: WO
Inventors: Mitsuru Hoshino; Hiroo Jin; Satoshi Kashima; Mitsushige Sakamoto
Original assignee: Honshu-Shikoku Bridge Authority
Priority date: 1996-03-14
Filing date: 1997-03-12
Publication date: 1997-09-18
Also published as: JPH09250935A

Abstract

A method of seafloor survey using a pontoon moving at short time intervals on the surface of a deep sea of strong tidal current, which can be applied economically and accurately in a simple constitution requiring a smaller sea surface area, as compared with a conventional method. To attain this method, a plurality of omnidirectional screw propellers (42) are provided on the bow and stern of a self-propelling pontoon (30). The motors (43) for these propellers (42) are controlled by a position controller (49) comprising position measuring unit (45), gyrocompass (46), an anemoscope-anemometer (47) and a control arithmetic unit (48), whereby the self-propelling pontoon (30) is automatically retained in a predetermined site. After a casing pipe (12) has been fixed to the self-propelling pontoon (30) via a pipe support unit (29) and extended and set up substantially perpendicularly on a survey site, a boring machine (13) is driven as the self-propelling pontoon (30) is retained on a predetermined site by an automatic retaining system, in order to excavate the sea bottom (10) by a boring pipe (14).

Description

Description Submarine ground survey method Technical field

The present invention is based on the fact that the survey point is moved over a short period of several weeks to several months on the sea where the water depth is deep (100 to 200 m) and the tidal current is fast (about 5 knots). It relates to a seabed survey method for conducting a seabed drilling survey of the ground. Background art

Offshore drilling for undersea ground surveys is restricted by the natural environment, such as water depth, tides, waves, and seafloor topography, and by the social environment, such as the use of the sea for fishing and navigation of ships.

The offshore drilling method is classified mainly based on work scaffolds, because it is greatly affected by natural conditions such as water depth and tidal current among the above restrictions.

There are various methods for this work scaffold. Typical methods are the offshore installation type shown in Fig. 10 (a), the seabed sitting type shown in Fig. 10 (b), and Fig. 10 ( c) There are shipboard types as shown in c).

(a) Offshore installation type: Fixed or installation type scaffolds 11 are connected by welding, bolts, etc. using copper or copper pipes, assembled in a turret type, and directly installed on the seabed 10 and fixed or installed. A boring machine 13 is mounted on a base 16 on the upper part of the scaffold 11, a casing pipe 12 is provided at the center, and the seabed 10 is dug through the boring pipe 14 in the casing pipe 12. Currently, This method has become the mainstream of offshore scaffolds. There are examples of use from shallow water to about 30 to 40 m.

(b) Seabed-bottomed type: In the survey from the sea, if the depth of the water and the sway of the seawater are major obstacles to the survey, the boring machine 13 should be submerged in the seabed to eliminate these obstacles, and the survey vessel 18 This is the method of excavating by remote control. In more detail, the base 16 on which the boring machine 13 is mounted is fixed to the seabed 10 by the leg device 15, and the survey ship 18 equipped with the control device 19 is floated on the sea surface 17, The research vessel 18 is connected to the seabed base 16 by a detent wire 20. Then, power and control signals are sent from the research vessel 18 via the cable 21 to control the boring machine 13 on the seabed.

(c) Shipboard type: When the water depth becomes deeper, the above sea-mounted type and seabed-mounted type are too expensive, so that boring from the ship or from the float is advantageous. In this method, anchor blocks 22 and anchors are submerged on the seabed 10 to prevent rocking of the ship and the float, and the survey ship 18 (or float) is fixed by the detent wire 20 and the survey ship It is operated by a boring machine 13 mounted on 18.

Each of the above methods has the following problems when conducting seabed drilling surveys at a site with large water depth and strong tide while moving to the survey site every short period.

The offshore installation type shown in Fig. 10 (a) is suitable for long-term drilling because of the high cost of assembling and installation, but is also suitable for boring surveys where the survey point is moved every short period. Not. Also, if the water depth is more than 10 Om and the current is strong, the cost is too high.

The seabed seating type shown in Fig. 10 (b) is also used when the water depth exceeds 100m, but since the boring machine 13 is installed on the seabed, Dive work is required, and full-automatic or semi-automatic control is required.Since the control is complicated, the mechanism is complicated and expensive, and it is suitable for long-term boring. It is not suitable for boring surveys where the survey points are moved every time.

The shipboard type shown in Fig. 10 (c) is simple in equipment and easy to move the survey point, but has large fluctuations and difficulties in survey accuracy. Depending on the hardness of the seabed 10, if the boring pipe 14 is tilted more than 3 degrees with respect to the vertical, it may be damaged, so the range of use is limited. In addition, since the detent wire 20 generally needs to be about three times as long as the water depth, for example, if the water depth is 100 m, the sea area is as large as 60 Om X 60 Om vertically and horizontally. Occupying the river, obstructing the navigation of ships, and infringement of fishing rights. An object of the present invention is to provide a method that is inexpensive and has a simple mechanism when conducting a seabed drilling survey while moving over the sea at high water depths and strong currents at short intervals. Things.

It is another object of the present invention to provide a method in which the fluctuation is extremely small and the survey accuracy is high, while using a simple method of the apparatus using the self-propelled barge.

In addition, the present invention does not use a detent wire for mooring a self-propelled barge, occupy the sea area, hinder the navigation of the ship, or infringe the fishing right It is intended to provide a method. Disclosure of the invention

The present invention is provided with a plurality of omnidirectional thrusters 42 at the head and stern of the self-propelled barge 30, and the plurality of omnidirectional thrusters 42 are respectively connected to motors 43. The motor 43 is a position control device consisting of a position measuring device 45, a gyro compass 46, an anemometer 47, and a control arithmetic device 48. The self-propelled barge 30 is equipped with a pipe supporting device 12 to install a ricketing pipe 12 on the self-propelled barge 30 to investigate the seabed 10. This is the method of surveying the seabed ground.

With the above configuration, after the casing pipe 12 is built almost vertically at the survey point, the boring machine 13 is driven while the self-propelled barge 30 is held at a fixed point by the automatic fixed point holding system. A drilling survey is conducted by drilling the seabed 10 with a boring pipe 14.

In order to keep the casing pipe 12 approximately vertical during the boring survey, the thrust of each omnidirectional thruster 42 is adjusted to maintain the position and orientation of the self-propelled barge 30 at a fixed point. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a front view showing a state in which a casing pipe 12 is installed on a self-propelled barge 30 for explaining a seabed investigation method according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a cross-sectional view of the casing pipe 12 used in the seabed survey method according to the present invention.

FIG. 4 is a partially cutaway sectional view showing a connection state of the casing pipe 12 and the sinker 34 used in the seabed survey method according to the present invention. FIG. 5 (a), (b), (c) and (d) are explanatory diagrams showing the work sequence for installing the casing pipe 12 at the survey site.

FIG. 6 is a flowchart of the fixed point holding system of the self-propelled barge 30.

FIG. 7 (a) is a waveform diagram showing the behavior of the self-propelled barge 30 until it converges to the destination point of the casing pipe 12 by the fixed point holding system.

Fig. 7 (b) shows the self-propelled barge 30 and the casing pipe 1 2 FIG. 9 is a waveform diagram showing a behavior of the fixed point holding system until the casing pipe 12 converges to a destination point when an external force is applied to the casing pipe.

FIG. 8 is a plan view showing an example in which the casing pipe 12 is installed on the side surface of the self-propelled barge 30.

FIG. 9 is a plan view showing an example in which the self-propelled barge 30 is provided with three omnidirectional thrusters 42.

Fig. 10 shows different examples of conventional offshore scaffolds for offshore drilling. Fig. 10 (a) is a sea-based scaffold, and Fig. 10 (b) is a seat on the seabed. Formula, FIG. 10 (c) is an explanatory diagram of the shipboard type. BEST MODE FOR CARRYING OUT THE INVENTION

In FIGS. 1 to 4, reference numeral 30 denotes a self-propelled barge equipped with an automatic fixed point holding system for a ship. This self-propelled barge 30 is, for example, a half catamaran type, and is equipped with a total of four omnidirectional thrusters 42, one at each of the four corners of the bow and stern of each catamaran. . Each of these omnidirectional thrusters 42 is connected to a motor 43, and these motors 43 consist of a position measuring device 45, a gyro compass 46, a wind anemometer 47, and a control arithmetic device 48. The position control device 49 automatically holds the fixed point. The upper deck of the self-propelled barge 30 is equipped with a boring machine 13 and a hoist 28 at the center, and a drive unit 44 at the stern.

Each of the omnidirectional propulsion units 42 and the motors 43 provided in the four corners can be configured as four electric propulsion units driven by one main engine and a generator. In addition, one independent main engine can be provided for each omnidirectional thruster 42.

The omnidirectional turning propulsion device 42 employs a variable pitch propeller to save power and improve response time by shortening response time. _a

6

The hull structure of the self-propelled barge 30 is considered to have different fixed point holding accuracy depending on the support position of the casing pipe 12 (center, front, side, etc.). The work space is large and the workability is good.

For this reason, the hull structure of the self-propelled barge 30 is a semi-twin-hull type in which the entrance groove 33 is formed from the bow side to the center of the hull. The hull dimensions are about 50 to 60 m in length and about 15 to 20 m in width when the water depth is 100 to 20 Om.

The casing pipe is provided by the pipe support device 29 of the self-propelled barge 30.

1 and 2 are vertically mounted, and the lower end of the casing pipe 12 is connected to a sinker 34 fixed to the seabed 10.

Since the tidal force received by the casing pipe 12 is a dominant factor that determines the size of the self-propelled barge 30, the cross section of the casing pipe 12 is made to have a streamlined shape as shown in Fig. 3. By doing so, the tidal force can be reduced to one-third that of a circular section.

In this case, the connecting portion of the sinker 34 on the seabed 10 and the pipe supporting device 29 of the self-propelled barge 30 are automatically connected so that the casing pipe 12 automatically turns to the direction with the least tidal force. The part has a rotatable structure.

Specifically, as shown in Figs. 3 and 4, the casing pipe 1

A streamline wing section 38 is integrally provided on one side in the length direction of 2, and a buoyancy is provided as a double structure in which an inner pipe 27 is housed so that the specific gravity is substantially the same as that of seawater.

As a structure for rotatably connecting the casing pipe 12, as shown in FIG. 4, a ball part 40 integrally provided at the lower end of the casing pipe 12 and a ball receiver provided on the sinker 34. Part 4 consisting of part 1 _?

It is supported rotatably in all directions at point 39. A similar configuration is also supported on the pipe support device 29 side of the self-propelled barge 30 shown in FIG.

As shown in FIG. 1, a buoy 35 is provided above the casing pipe 12 so that the casing pipe 12 can stand vertically vertically in the sea. However, the buoy 35 is not particularly essential in the present invention. The ship automatic fixed point holding system will be described in more detail.

In FIGS. 1 and 2, the self-propelled barge 30 is equipped with four omnidirectional thrusters 42, one at each of the four corners of the hull and stern of each catamaran. However, these omnidirectional thrusters 42 generate thrust toward the center O of the self-propelled barge 30 and generate the same hydraulic power in the standard state, and there is no tidal current or wind disturbance. The position and bearing of the self-propelled barge 30 are maintained.

In FIG. 2, the symbol a indicates the direction of the thrust of each omnidirectional thruster 42 toward the center O of the self-propelled barge 30, and the symbol b indicates the thrust for obtaining the thrust a. Shows the direction of water flow generated from each omnidirectional thruster 42.Each omnidirectional thruster 42 has thrust adjusting means capable of adjusting the magnitude of thrust, and thrust direction adjusted. Propulsion device turning means. This automatic fixed point holding system is designed to maintain the position and orientation of the self-propelled barge 30 by adjusting the direction and magnitude of each thrust of the four omnidirectional thrusters 42 according to the disturbance. A control arithmetic unit 48 including first arithmetic means 51, second arithmetic means 52, third arithmetic means 53, and fourth arithmetic means 54 is provided.

The first arithmetic means 51 is configured to determine the direction of the thrust required for maintaining a fixed point of the self-propelled barge 30 based on the detection signals from the position measuring device 45 of the self-propelled barge 30 and the gyro compass 46. Function to calculate the size and turning moment have.

The second calculating means 52 has a function of calculating each thrust at the current turning angle of each omnidirectional thruster 42 to obtain the turning moment obtained by the first calculating means 51. Is provided. Then, with the current turning angle of each omnidirectional turning propulsion device 42, if the above-mentioned turning moment cannot be obtained by the second calculating means 52, the current turning angle of each omnidirectional turning propulsion device 42 becomes A slight adjustment is made by the propulsion device turning means attached to the direction turning propulsion device 42.

The third calculation means 53 is provided with all the components for performing the required horizontal movement of the self-propelled barge 30 when the second calculation means 52 can obtain the turning moment. It has a function to calculate the thrust of the directional turning thruster 42.

The fourth arithmetic means 54 has a function of adding the thrust of each omnidirectional thruster 42 obtained by the second arithmetic means 52 and the third arithmetic means 53. In order to realize the thrust of each omnidirectional thruster 42 obtained by the fourth arithmetic means 54, the thrust adjusting means attached to each omnidirectional thruster 42 must be A command is sent from a command means in the control arithmetic unit 48.

Next, referring to FIGS. 5 (a), (b), (c), and (d), the work sequence of moving the casing pipe 12 to the survey point and installing it will be described.

Fig. 5 (a): The sinker 34 connected to the lower end of the casing pipe 12 is suspended by the lifting wire 36 of the crane 32 of the anchorage vessel 31 and the upper end is buoyed. Float at 35, and tow up to the survey point with a docking boat 31 so that the casing pipe 12 is substantially horizontal on the sea surface. At this time, the upper end of the casing pipe 12 is connected to the self-propelled barge 30 by a connecting wire 37. Fig. 5 (b): When the vehicle arrives at the survey site, the lifting wire 36 of the crane 32 is paid out. Then, the sinker 34 sinks underwater by its own weight, the upper end of the casing pipe 12 remains floating on the buoy 35, and the casing pipe 12 gradually becomes vertical.

Fig. 5 (c): Shin power 34 falls on the survey point and casing pipe 12 is built almost vertically. When the casing pipe 12 becomes vertical, the self-propelled hull 30 enters so that the upper end portion of the casing pipe 12 enters the intake groove 33 of the self-propelled hull 30.

Fig. 5 (d): The self-propelled hull 30 enters and connects the casing pipes 12 until the casing pipe 12 is positioned on the pipe support device 29 of the self-propelled hull 30. When connecting the casing pipe 12 to the pipe support device 29, the self-propelled barge 30 is allowed to slide up and down so as to be allowed to move up and down the sea surface 17 due to tides and waves.

As described above, after the recapping pipe 12 is erected almost vertically at the survey point according to Figs. 5 (a), (b), (c), and (d), the self-propelled barge 30 is transferred to the automatic fixed point holding system. The boring machine 13 is driven while maintaining the fixed point, and the boring pipe 14 is used to excavate the seabed 10 to conduct a boring survey.

In order to hold the casing pipe 12 approximately vertically during the boring survey, it is necessary to adjust the thrust of each omnidirectional thruster 42 to maintain the position and orientation of the self-propelled barge 30 at a fixed point. The necessary operations are described below, and the operation thereof is described below with reference to the flowchart of FIG.

In the first calculation means 51, when the position and direction of the self-propelled hull 30 are affected by the tidal current and wind disturbance, the self-propelled hull 30 is calculated based on the self-propelled hull 30. In order to return to the state of self-propelled hull 30, the position control device 49 for detecting the position of the self-propelled hull 30 and the detection signal The direction and magnitude of thrust required for ship 30 and _The operation of calculating the turning moment of the _{1 Q} hull 30 is performed.

Next, the second calculating means 52 performs an operation of calculating the magnitude of each thrust at the current turning angle of the plurality of omnidirectional thrusters 42. At the current turning angle of each omnidirectional turning propulsion device 42, if the turning moment cannot be obtained even when the thrust is changed, that is, has the turning moment been obtained? But

In the case of NO, an operation of slightly adjusting the turning angle of each omnidirectional turning propulsion device 42 is performed by the propulsion device turning means.

In the third calculating means 53, when the turning moment can be obtained by the second calculating means 52, ie, has the turning moment been obtained? In the case of YS, a calculation is performed to obtain the thrust of each omnidirectional thruster 42 for horizontal movement necessary to return the self-propelled barge 30 to its current position.

In the fourth arithmetic means 54, the thrust of each omnidirectional thruster 42 obtained by the second arithmetic means 52 and the third arithmetic means 53 is added. In order to realize the thrust of each omnidirectional thruster 42 obtained in this way, the operation of instructing the thrust adjusting means of each omnidirectional thruster 42 from the command means of the control arithmetic unit 48 內 is effective. Done.

With the above operation, each omnidirectional thruster 42 has its thrust direction directed toward the center O of the hull as a reference state, and the turning angle of each omnidirectional thruster 42 from this reference state is It is suppressed to be as small as possible.

Therefore, the water flow containing bubbles generated from each omnidirectional thruster 42 is not sucked into the other omnidirectional thrusters 42.

The thrust of each omnidirectional thruster 42 depends greatly on the speed of the water flowing into the same omnidirectional thruster 42, and the higher the inflow speed, the smaller the thrust tends to be. If thrust flows into the omnidirectional thruster 42, sufficient thrust cannot be obtained.

However, the omnidirectional thrusters 4 2 Each of the omni-directional thrusters 42 has the required thrust in response to a command from the thrust adjusting means, since the water flow containing bubbles that generate air is prevented from flowing into the other omni-directional thrusters 42. As a result, the position and orientation of the self-propelled barge 30 can be properly maintained.

In this way, the self-propelled barge 30 is maintained at a fixed point by adjusting the hydraulic power of each omnidirectional thruster 42 while minimizing the adjustment of the turning angle of each omnidirectional thruster 42. The response to the disturbance is made quickly.

Operate the boring machine 13 while controlling the fixed point of the self-propelled barge 30 to investigate the ground on the seabed 10. When the survey at that point is completed, move to another survey point as described in Fig. 5 and repeat the survey while maintaining the self-propelled barge 30 at the fixed point.

Next, when the accuracy of the fixed point holding control was confirmed, the following results were obtained, which will be described.

As a condition for confirming the accuracy of the fixed point holding control, a boring pipe 14 was attached to the center of the self-propelled barge 30 and the casing pipe 12 had a diameter of 1.

2 m circular cross section, external force, tidal current 5 kn, wind speed 15 mZ seconds, wave height 1 m, 3 m in front and back (x = 3 m), 5 m in left and right direction (y = 5 m) The behavior from to was converged.

In the control of the self-propelled barge 30, the direction of action of the external force was set to the front in order to detect the tidal current direction and always direct the direction of the self-propelled hull 30 to the tidal current direction.

As a result, as shown in FIG. 7 (a), it almost converged in less than 40 seconds.

Next, while converging to the target position, the direction of the wave was changed by 20 degrees and the direction of the wind was changed by 30 degrees to confirm the detection error of the tidal current direction and the responsiveness of sudden changes in the wind direction.

As a result, almost converged in about 50 seconds as shown in FIG. 7 (b). In addition, _The single pipe 12 had a streamlined cross section of 1.2 × 2.4 m in diameter as shown in FIG.

In the embodiment, as shown in FIG. 2, the case where the casing pipe 12 is installed at the center of the self-propelled barge 30 has been described. However, the present invention is not limited to this, and as shown in FIG. 8, a casing support pipe 12 can be provided by providing a pipe support device 29 on the side surface of the self-propelled barge 30. Although not shown, it may be installed at the bow of the self-propelled barge 30.

However, the installation position of the casing pipes 12 is determined by the reason that the convergence time for maintaining the fixed point of the self-propelled barge 30 is fast, the necessary materials for boring, and the installation space of the equipment is large. The center of the self-propelled barge 30 is the best.

In the above-described embodiment, a case has been described in which the self-propelled barge 30 is provided with a total of four omnidirectional thrusters 42, one at each of the forward and rear corners of the stern. However, the present invention is not limited to this. As shown in Fig. 9, one omnidirectional turning propulsion unit 42 having thrust in the forward direction is provided at each of the two corners of the stern of the self-propelled barge 30. However, a total of three omnidirectional thrusters 42 having a thrust in the left-right direction at the center of the bow may be provided. Industrial applicability

As described above, the method of investigating the seabed ground according to the present invention can be applied to a deep pier (100 to 200 m), a tidal current (approximately 5 knots), a pier to the seabed ground, and other structures. It is suitable to be used when conducting surveys on the seabed under the seabed while moving from one survey point to another every few weeks, such as a preliminary survey of the seabed for the construction of a submarine ground.

Claims

The scope of the claims

1, a self-propelled hull 30 equipped with a position control device 49 for maintaining a fixed point on the sea surface 17 A submarine ground survey method characterized by the following.

2. The method of claim 1, wherein the casing pipe 12 is provided with a sinker 34 at a lower end and a pipe 35 at an upper side.

3. The method of claim 1 or 2, wherein the self-propelled barge 30 is provided with a plurality of omnidirectional turning propulsion units 42 at the head and stern.

4. A plurality of omnidirectional propulsion devices 4 2 are connected to motors 4 3, respectively. These motors 4 3 are a position measuring device 45, a gyro compass 46, a wind anemometer 47, and a control arithmetic device 4. 4. The method according to claim 3, wherein a position control device configured to automatically maintain a fixed point is used by a position control device composed of the position control device.

5. The control arithmetic unit 48 adjusts the direction and magnitude of each thrust of the plurality of omnidirectional thrusters 42 according to the disturbance so that the position and orientation of the self-propelled barge 30 can be maintained. First arithmetic means 51, second arithmetic means 52, third arithmetic means 53, and fourth arithmetic means 54 are built in control arithmetic unit 48, and the first arithmetic means is provided. 51 indicates the direction and magnitude of thrust necessary to maintain the fixed point of the self-propelled barge 30 and the turning moment based on the detection signals from the position measurement device 45 of the self-propelled barge 30 and the gyro compass 46. The second calculating means 52 has a function of calculating the current turning angle of each omnidirectional propulsion device 42 for obtaining the turning moment calculated by the first calculating means 51. In the present turning angle of each omnidirectional turning propulsion device 42, when the above-mentioned turning moment cannot be obtained by the second calculating means 52, each omnidirectional turning propulsion device is provided. The current turning angle of the thruster 42 is slightly adjusted by the thruster turning means attached to the omnidirectional thruster 42, and the third arithmetic means 53 is When the turning moment can be obtained by the second calculation means 52, the thrust of each omnidirectional thruster 4 2 for performing the required horizontal movement of the self-propelled barge 30 is performed. The fourth arithmetic means 54 includes an addition of the thrusts of the omnidirectional thrusters 42 obtained by the second arithmetic means 52 and the third arithmetic means 53, respectively. The thrust of each omnidirectional thruster 42 obtained by the fourth arithmetic means 54 is provided. A command is sent from a command means in the control arithmetic unit 48 to a thrust adjusting means attached to each omnidirectional thruster 42 so as to be realized. Submarine ground survey method described in 3.

6. In order to move the casing pipe 12 to the survey point and install it, the casing pipe 12 is suspended by the crane 32 of the anchorage vessel 31 and towed to the control point. When arriving, the crane 32 draws out the relocating pipe 12 and builds it almost vertically, connects this casing pipe 12 to the pipe support device 29 of the self-propelled hull 30, and connects the self-propelled The seabed according to claim 1, 2, 3, 4, or 5, wherein the boring machine 13 is driven while the ship 30 is automatically held at a fixed point, and the boring pipe 14 is used to excavate the seabed 10 to perform a boring survey. Ground survey method.