JP5053181B2 - Removal method of legged structure - Google Patents

Description

  The present invention relates to a method for removing a legged structure.

  Conventionally, many legged structures such as bridges and work platforms have been constructed on the water. If these legged structures become unusable due to corrosion or aging, they must be removed before they can collapse. In order to remove the bridge, there is a method of cutting the bridge girder while supporting the bridge girder with the lifting mechanism provided on the work table ship arranged below the bridge girder and lowering the cut bridge girder onto the work table ship with the lifting mechanism (for example, , See Patent Document 1).

JP-A-10-280328

  However, when the legged structure is installed in a water area where local flow or irregular waves from other directions are generated, the conventional removal method causes severe shaking of the hull of the work table ship, which may cause danger to the removal work. It will be difficult.

  The present invention has been made in view of such a problem, and the object of the present invention is to provide a method for removing a legged structure that can be safely operated in a water area where water flow and wave conditions are severe. is there.

In order to achieve the above-mentioned object, the present invention includes a step (a) of positioning a work table ship under the floor slab of a legged structure to be removed, and a lift provided on the work table ship. A step (b) of lowering a possible spud to the bottom of the water, a step (c) of applying a vertical load to the spud and fixing it to the bottom of the water, and the work table ship is levitated and installed on the work table ship A step (d) of contacting the floor slab with the receiving frame installed on the supported support frame, a step (e) of cutting the legs of the legged structure using a cutting device, and raising the spud And (f) moving the work table ship;
It is the removal method of the structure with a leg characterized by comprising.

  Between the step (e) and the step (f), a step (g) of creating a gap between the upper and lower portions of the leg cutting position by floating the work table ship may be further provided.

  In the step (a), for example, the floor slab is brought into contact with a guide provided on the cradle to position the work table ship. For example, a wire saw device connected to a weight is used as the cutting device. In step (e), a wire is arranged around the leg, and the leg is cut while the wire saw device is moved by the action of the weight.

  In step (d), the work table ship is lifted up while making adjustments so that the spud does not escape from the bottom of the water. In step (d), the floor slab is not installed on the work table ship, but instead of the work table ship being lifted, the jack provided on the work table ship is extended to extend the floor slab. You may receive the load of.

  In the present invention, by using the spud, the work table ship can be prevented from shaking under sea conditions with waves and currents. In addition, when a wire saw device is used as a cutting device, the structure can be reliably cut without greatly affecting adjacent facilities.

  ADVANTAGE OF THE INVENTION According to this invention, the removal method of the structure with a leg which can work safely in the water area where the flow of water and the state of a wave are severe can be provided.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a lifting platform 1 to be removed and a work table ship 9 used for removal. 1 (a) is an elevation view seen from the side of the work table ship 9, and FIG. 1 (b) is a cross-sectional view taken along arrows AA shown in FIG. 1 (a). FIG. 1C is a plan view of the work platform ship 9 as seen from the direction of the arrow C shown in FIG.

  As shown in FIG. 1A, the lifting platform 1 which is a structure with legs scheduled to be removed includes a leg portion 5, a floor slab 3, and the like. The leg 5 is supported on the ground 7 at the bottom of the water. The floor slab 3 is attached to the leg portion 5 and can be moved up and down along the leg portion 5.

  As shown in FIGS. 1A and 1C, a spud 11 that can be moved up and down is provided inside the work table ship 9. One end of a spud wire 23 is connected to the spud 11. The other end of the spud wire 23 is connected to a spud winch 21 provided on the work table ship 9. The spud 11, the spud wire 23, and the spud winch 21 are provided, for example, at four locations.

  On the work table ship 9, support frames 13 are installed at predetermined intervals. A receiving frame 15 is installed on the support frame 13. A guide 17 is provided near the end of the upper surface 14 of the cradle 15. As shown in FIG. 1B, a scaffold 19 is provided on the side surface 16 of the support base 13. In addition, the scaffold 19 shown by a dotted line in FIG. 1 (c) is in a state where it is extended in the step shown in FIG. 3, and the leg part 5 shown by a dotted line is a leg after positioning in the step shown in FIG. The position of the part 5 is shown.

  In the process shown in FIG. 1, the work table ship 9 is towed to the vicinity of the lifting platform 1 to be removed using a charter. Then, anchors (not shown) are driven on the ground 7 on the four sides of the work table ship 9 by a lifting ship (not shown), and the work table ship 9 is moored.

  FIG. 2 is a diagram illustrating a process of causing the work table ship 9 to enter below the lifting platform 1. 2A is an elevation view seen from the side of the work platform 9, and FIG. 2B is a cross-sectional view taken along arrows DD shown in FIG. 2A. .

  In the process shown in FIG. 2, the work table ship 9 is shown in FIG. 1 by winding and unwinding an anchor wire (not shown) connected to the anchor (not shown) with a ship maneuvering winch (not shown). It is moved in the direction of the arrow B, and is entered below the floor slab 3 of the lifting platform 1 as shown in FIG. Next, the floor slab 3 of the lifting platform 1 is brought into contact with the guide 17 provided on the work table ship 9 by winding and unwinding the anchor wire (not shown), thereby positioning the work table ship 9.

  In the process shown in FIG. 2, after positioning the work table ship 9, the spud 11 is lowered to the bottom 7 of the water bottom. Then, a load in the direction indicated by the arrow E is applied to the spud 11 using the spud wire 23, the spud winch 21, and the like, and the lower end 24 of the spud 11 is fixed to the ground 7 at the bottom of the water.

  FIG. 3 is a diagram showing a process of levitating the work table ship 9. 3A is an elevation view seen from the side of the work platform 9, and FIG. 3B is a cross-sectional view taken along the arrow FF shown in FIG. 3A. .

  In the process shown in FIG. 3, the ballast is drained, the work table ship 9 is floated in the direction of arrow G, and the receiving table 15 and the floor slab 3 of the lifting table 1 are brought into contact with each other. When the work table ship 9 is levitated, the load applied to the spud 11 is adjusted so that the spud 11 does not come off from the ground 7 at the bottom of the water.

  FIG. 4 is an enlarged view around the scaffold 19. FIG. 4 is an enlarged view of a range H shown in FIG. As shown in FIG. 4, the scaffold 19 provided on the support base 13 includes a scaffold 19a, a scaffold 19b, a scaffold winch 27, a scaffold wire 29, and the like. One end of the scaffold 19 a is attached to the support frame 13 by a pin 25. The scaffold 19b is integrated with the scaffold 19a and slides along the scaffold 19a. The scaffold winch 27 is installed on the support frame 13. The scaffold wire 29 has one end coupled to the scaffold 19 a and the other end coupled to the scaffold winch 27.

  In the step shown in FIG. 3, after the work table ship 9 is levitated in the direction of arrow G, the scaffold 19 is rotated in the direction shown by arrow I as shown in FIG. Next, the scaffold 19b is slid in the direction indicated by the arrow J, and the scaffold 19 is extended to the vicinity of the leg 5 of the lifting platform 1 as shown in FIG. 3 (b) and FIG. For example, as shown in FIG. 1C, the scaffold 19 has a shape that sandwiches the leg portion 5 when it is extended.

  FIG. 5 shows a step of cutting the leg portion 5. FIG. 5 is an enlarged view around the scaffold 19. As shown in FIG. 5, the cutting device for cutting the leg portion 5 includes a cutting wire 31, a wire saw unit 33, a weight 35, and the like. The cutting wire 31 is connected to the wire saw unit 33. The wire saw unit 33 is installed on the work table ship 9, for example. The wire saw unit 33 travels by moving means (not shown) provided on the lower surface. The weight 35 is installed by being hooked on a plurality of pulleys 34 attached to the support frame 13.

  In the step shown in FIG. 5, first, the cutting wire 31 is arranged around the leg portion 5 using the scaffold 19. Then, the leg 5 is cut with the cutting wire 31. At this time, the weight 35 is lowered according to the cutting amount as indicated by the arrow K, and tension is applied so that the cutting wire 31 does not loosen. The wire saw unit 33 travels in the direction indicated by the arrow L according to the amount of descent of the weight 35 by a moving means (not shown). The legs 5 are cut in a state in which the cradle 15 is pressed against the upper floor slab 3 by the buoyancy of the work table ship 9.

  FIG. 6 is a diagram illustrating a process of separating the leg portion 5. 6A is an elevation view seen from the side of the work table ship 9, and FIG. 6B is a cross-sectional view taken along arrows MM shown in FIG. 6A. .

  In the process shown in FIG. 6, the ballast is drained to float the work table ship 9 in the direction indicated by the arrow N. And the clearance gap 37 is made between the upper part 5a of the cut surface of the leg part 5, and the lower part 5b.

  FIG. 7 is a diagram illustrating a process of moving the work table ship 9. 7A is an elevation view seen from the side of the work table ship 9, and FIG. 7B is a cross-sectional view taken along arrow OO shown in FIG. 7A. .

  In the process shown in FIG. 7, first, the spud 11 is raised to release the work table ship 9 from being fixed. Then, an anchor wire (not shown) connected to an anchor (not shown) installed in the water is wound or unwound by a marine maneuvering winch (not shown), so that the work table ship 9 is indicated by an arrow P. Move in the direction. Further, after the floor slab 3 and the receiving base 15 are secured, the work table ship 9 is towed by a tugboat (not shown).

  As described above, according to the first embodiment, the work table ship 9 is fixed to the bottom 7 using the spud 11, so that the work table ship 9 can be shaken under sea conditions with waves and flows. This can reduce the operating rate of offshore construction. Moreover, since the leg part 5 is cut | disconnected using a wire apparatus, there is little influence on an adjacent plant | facility and the leg part 5 can be cut | disconnected reliably. Furthermore, since the leg portion 5 is cut while the floor slab 3 is supported by the support frame 13, the receiving frame 15, and the spud 11, the force fluctuation before and after the cutting is small, and even an aged structure can be safely cut and removed. Is possible.

  In the first embodiment, the work table ship 9 is levitated by draining the ballast in the process shown in FIG. 6, but the work table ship 9 need not necessarily be levitated. For example, by applying a force that pushes upward when receiving the load of the floor slab 3 with the support base 15, a gap is formed between the upper part 5 a and the lower part 5 b of the cut surface simultaneously with the cutting of the leg part 5. Sometimes it is made.

  Next, a second embodiment will be described. FIG. 8 is a view showing a method for removing the lifting platform 1 using the stacked jack 39. 8A is an elevation view seen from the side of the work platform 9, and FIG. 8B is a cross-sectional view taken along arrows QQ shown in FIG. 8A. .

  The configuration of the work platform 9 used in the second embodiment is substantially the same as the configuration of the work platform 9 shown in FIG. 1, but instead of the support platform 13 and the receiving platform 15 on the work platform 9. A plurality of stacked jacks 39 are provided. The stacked jack 39 is configured by stacking several stages of jacks having a longer stroke than usual.

  The method for removing the lifting platform 1 in the second embodiment is substantially the same as in the first embodiment. Also in the second embodiment, an anchor (not shown) is first driven by a lifting ship (not shown), and the work table ship 9 is moored. Next, the work table ship 9 is caused to enter below the floor slab 3 of the lifting platform 1 by winding and unwinding the anchor wire (not shown). Then, after the spud 11 is lowered to the water bottom ground 7, a load is applied to the spud 11 using the spud wire 23, the spud winch 21, etc., and the lower end 24 is fixed to the water bottom ground 7.

  In the second embodiment, after the spud 11 is fixed to the ground 7, instead of draining the ballast and floating the work table ship 9, the stacked jack 39 is raised and the stacked slab 39 is used as the floor slab. Receive a load of 3. And the leg part 5 of the lifting platform 1 is cut | disconnected using a wire saw apparatus (not shown).

  FIG. 9 is a diagram illustrating a process of lowering the floor slab 3. In the second embodiment, after cutting the leg portion 5, the spud 11 is raised to release the work table ship 9, and the work table ship 9 is taken up by winding and unwinding the anchor wire (not shown). Move. Then, the stacked jack 39 is contracted in the direction of the arrow R shown in FIG. 8A, and the floor slab 3 is lowered onto the work table ship 9. Further, after the floor slab 3 and the work table ship 9 are secured, the work table ship 9 is towed by a tugboat (not shown).

  As described above, according to the second embodiment, since the work table ship 9 is fixed to the ground 7 on the bottom using the spud 11, the work table ship 9 can be shaken under sea conditions with waves and flows. This can reduce the operating rate of offshore construction. Moreover, since the leg part 5 is cut | disconnected using a wire apparatus, there is little influence on an adjacent plant | facility and the leg part 5 can be cut | disconnected reliably.

  In the first and second embodiments, the leg 5 is cut using the wire saw device, but other cutting methods such as a disk cutter method may be used as a method that does not need to consider the influence on adjacent facilities. May be used. Moreover, although the case where the lifting platform 1 was removed was demonstrated in 1st and 2nd embodiment, the removal method of this invention is applicable also to legged structures other than a lifting platform.

  As mentioned above, although preferred embodiment of the legged structure concerning this invention was described referring an accompanying drawing, this invention is not limited to this example. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

Schematic diagram of lifting platform 1 scheduled for removal and work platform 9 used for removal The figure which shows the process of making the work platform ship 9 approach below the raising-lowering stand 1 The figure which shows the process of surfacing the work platform ship 9 Enlarged view around scaffold 19 The figure which shows the process of cut | disconnecting the leg part 5. The figure which shows the process of isolate | separating the leg part 5. The figure which shows the process of moving the work platform ship 9 The figure which shows the method of removing the raising / lowering stand 1 using the stacked jack 39 The figure which shows the process of lowering the floor slab 3

Explanation of symbols

1 ......... Elevating base 3 ......... Slab 5 ......... Leg 9 ......... Working vessel 11 ......... Spud 13 ......... Supporting base 15 ......... Stand base 17 ......... Guide 19, 19a 19b ......... Staff 31 ......... Cutting wire 33 ......... Wire saw unit 35 ......... Weight 37 ......... Gap 39 ......... Stand-up jack

Claims (6)

A step (a) for positioning the work table ship under the floor slab of the legged structure to be removed;
A step (b) of lowering a vertically movable spud provided on the work table ship to the bottom of the water;
Applying a vertical load to the spud and fixing it to the bottom of the water (c);
A step (d) of floating the work table ship and bringing the receiving frame installed on a support frame installed on the work table ship and the floor slab into contact with each other;
Cutting the legs of the legged structure using a cutting device (e);
Raising the spud and moving the work table ship (f);
A method for removing a legged structure, comprising:   A step (g) is further provided between the step (e) and the step (f), wherein the work table ship is levitated to form a gap between the upper and lower portions of the leg cutting position. The method for removing a legged structure according to claim 1.   3. The legged structure according to claim 1, wherein in the step (a), the work table ship is positioned by bringing the floor slab into contact with a guide provided on the receiving stand. 4. Removal method. The cutting device is a wire saw device connected to a weight;
4. The method according to claim 1, wherein, in the step (e), a wire is disposed around the leg, and the leg is cut while the wire saw device is moved by the action of the weight. 5. Removal method of the structure with legs described.   The legged structure according to any one of claims 1 to 4, wherein in the step (d), the work table ship is floated while adjusting so that the spud does not come off from the bottom of the water. How to remove things. Without installing a receiving frame built on a support frame on the work table ship,
2. The load of the floor slab is received by the jack by extending a jack provided on the work table ship in place of the work table ship rising in the step (d). The removal method of the structure with a leg in any one of Claim 4.

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