Closure lid device and casing installation method

Abstract

To provide a blocking cover device that can easily block a tip opening part of a casing located underwater, and can prevent sea water from being left exposed inside the casing even if a long period of time elapses until drawing a cable within the casing after recovering a recovery portion of a drilling machine.SOLUTION: A blocking cover device 14 can include a recovery portion recovered in the rear of a drilling machine 1 therein, and comprises a cover body 15 covering an opening part 20 of a casing 2 located underwater and having an opening part 20 at a tip part. The cover body 15 comprises a cover body part 150 covering the opening part 20, cover side wall parts 151 continuously formed from the cover body part 150 and covering an outer peripheral surface of the casing 2, and outer peripheral cutoff parts 152 cutting off water between the cover side wall parts 151 and the outer peripheral surface of the casing 2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a closing cover device and a casing installation method for closing an open portion on the underwater side of a casing used to pull up and install a submarine cable for power transmission or communication extending from an offshore wind turbine or the like from underwater onto land. [Background technology]

[0002] To bring undersea power and communication cables ashore, they can be buried underground using the trenchless method, or in locations where trenchless methods are inappropriate, a pipe for running the cables can be constructed from land to underwater using the trenchless method. To construct a pipe for passing a cable using trenchless construction, a drilling machine is usually launched from a shaft dug on land and advanced into the sea while digging underground, and cylindrical pipes that form the tunnel's perimeter are then successively installed around the drilling machine's excavation track.

[0003] The diameter of the cable differs between power transmission and communication, but power transmission cables are larger, typically measuring around 200 mm at most. Furthermore, it is desirable to make the inner diameter of the tunnel small from the viewpoint of cost.

[0004] As described in Patent Document 1, a conventional method for lifting an undersea pipeline is known, which includes the steps of constructing a tunnel from a vertical shaft toward the seabed using a shield method, retrieving the shield machine once it has reached the seabed, opening the tip of the tunnel, and pulling a pipeline into the tunnel from the tip, and fitting a waterproof seal between the inner surface of the seaward tip of the tunnel and the outer surface of the pipeline to make the tip of the tunnel waterproof and drain seawater from the tunnel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-19473 Summary of the Invention [Problem to be solved by the invention]

[0006] In the method for lifting submarine pipelines as described in Patent Document 1, a waterproof seal is installed between the inner surface of the tip of the tunnel and the outer surface of the pipeline, but if the inner diameter of the tunnel is small, workers cannot enter, making the waterproofing work extremely difficult.

[0007] Furthermore, when passing power transmission cables for multiple offshore wind turbines through a tunnel, it may take several years from the time the tunnel is installed until the power transmission cables are passed through, due to the time it takes to build the generators, etc. In such cases, if the end of the tunnel is left open, the inside of the tunnel will remain exposed to seawater, and barnacles and shellfish will attach to the inside of the tunnel, which will not only hinder the work of pulling in the thick cables but may also damage the cable coating.

[0008] The problem that the present invention aims to solve is to provide a closing lid device and a casing installation method that can easily close the open part at the tip of a casing placed underwater, and that can prevent the inside of the casing from remaining exposed to seawater even if a long period of time passes between retrieving the excavator's retrieval part and pulling the cable into the casing. [Means for solving the problem]

[0009] The invention of claim 1 is a closing lid device that is capable of containing a recovery section that is recovered behind an excavator, and that is placed underwater and has an opening at its tip. The closing lid device comprises a lid body that covers the opening, a lid side wall portion that is formed continuously from the lid main body portion and covers the outer peripheral surface of the casing, and an outer peripheral water-stopping portion that stops water from flowing between the lid side wall portion and the outer peripheral surface of the casing. The closing lid device is characterized in that the lid body fixing means is capable of guiding the lid body so that it covers the opening and moving the lid side wall portion by sliding it along the outer peripheral surface of the casing. The invention of claim 2 is a closing lid device that is capable of containing a recovery section that is recovered behind an excavator, and that is placed underwater and has a lid body that covers an open section of a casing that has an open section at its tip, wherein the lid body comprises a lid main body portion that covers the open section, a lid side wall portion that is formed continuously from the lid main body portion and covers the outer peripheral surface of the casing, and an outer peripheral water-stopping portion that stops water from entering between the lid side wall portion and the outer peripheral surface of the casing, and the lid main body portion is equipped with a communication valve that can connect the outside to the casing side. The invention of claim 3 is a blocking lid device as described in claim 1 or claim 2, characterized in that the lid main body portion has an opening through which a cable can be passed and a small lid that removably covers the opening. The invention of claim 4 is a blocking lid device as described in claim 3, characterized in that the opening is provided with a cable protection material on the inner periphery of the opening to protect the cable passed through it. The invention of claim 5 is a casing installation method comprising: a casing placement step of placing a casing having an open part at its tip, which can include a recovery part inside to be recovered at the rear of an excavator, underwater; and a closing step of covering the open part with a lid body of a closing lid device, wherein the lid body comprises a lid main body part covering the open part, a lid side wall part formed continuously from the lid main body part and covering the outer peripheral surface of the casing, and an outer peripheral water stopping part that stops water from flowing between the lid side wall part and the outer peripheral surface of the casing, and in the closing step, the lid body a casing installation method in which a portion covers the open portion, the lid side wall portion covers the outer peripheral surface of the casing, the outer peripheral water-stop portion stops water from entering between the lid side wall portion and the outer peripheral surface of the casing, the closing lid device comprises a lid body fixing means for preventing the lid body from separating from the casing, and the closing process comprises a lid body moving process in which the lid body fixing means guides the lid body so that it covers and covers the open portion, and the lid side wall portion is moved by sliding it along the outer peripheral surface of the casing. The invention of claim 6 is a casing installation method described in claim 5, characterized in that in the casing placement process, the casing is placed in water while still containing the recovery section inside, and in the closing process, the open section is covered with the lid body of the closing lid device while still containing the recovery section inside the casing. The invention of claim 7 is a casing installation method comprising: a casing placement step of placing a casing having an open part at its tip, which can include a recovery part inside to be recovered at the rear of an excavator, underwater; and a closing step of covering the open part with a lid body of a closing lid device, wherein the lid body comprises a lid main body part that covers the open part, a lid side wall part that is formed continuously from the lid main body part and covers the outer peripheral surface of the casing, and an outer peripheral water stopping part that stops water from flowing between the lid side wall part and the outer peripheral surface of the casing, and in the closing step, the lid main body part covers the open part, and the lid side wall part closes the casing. a casing installation method characterized in that the casing includes a cover body of the blocking lid device that covers the outer surface of the casing, the outer watertight portion seals the gap between the lid side wall portion and the outer surface of the casing, the recovery portion includes an excavator body whose outer surface is inscribed between the casing's inner surface via a waterproof seal, the casing placement process placing the casing in water while still containing the recovery portion, the closing process covering the open portion with the lid body of the blocking lid device while still containing the recovery portion inside the casing, and after the closing process recovering the recovery portion to the rear of the casing. The invention of claim 8 is a casing installation method described in claim 5 or claim 6, characterized in that the lid main body portion is provided with a communication valve that can connect the outside with the casing side, and the communication valve is kept open during the lid body moving process. The invention of claim 9 is a casing installation method comprising: a casing placement step of placing a casing having an open part at its tip, which can include a recovery part inside to be recovered at the rear of an excavator, in water; and a closing step of covering the open part with a lid body of a closing lid device, wherein the lid body comprises a lid main body part that covers the open part, a lid side wall part that is formed continuously from the lid main body part and covers the outer peripheral surface of the casing, and an outer peripheral water stopping part that stops water between the lid side wall part and the outer peripheral surface of the casing, and in the closing step, the lid main body part covers the open part, the lid side wall part covers the outer peripheral surface of the casing, and the outer peripheral water stopping part stops water between the lid side wall part and the outer peripheral surface of the casing, This casing installation method is characterized in that, in the casing placement process, the casing is placed in water while still containing the recovery section inside, and in the closing process, the open section is covered with the lid of the closing lid device while still containing the recovery section inside the casing, and the closing lid device is provided with a lid fixing means for preventing the lid from separating from the casing, and in the closing process, the lid fixing means guides the lid so that it covers the open section and moves the lid side wall section by sliding it along the outer peripheral surface of the casing, and after the lid moving process, there is a recovery process for recovering the recovery section to the rear of the casing. The invention of claim 10 is a casing installation method described in any one of claims 5 to 9, characterized in that the lid main body has an opening through which a cable can be passed and a small lid that covers the opening, and the small lid is removed from the opening after the open portion is covered with the lid body and before the cable is passed through the opening. The following may also be considered as a separate invention. Means 1 is a closing lid device that can contain a recovery section inside that is recovered behind an excavator, and that is placed underwater and has a lid body that covers an open section of a casing that has an open section at its tip, wherein the lid body is characterized in that it has a lid main body section that covers the open section, a lid side wall section that is formed continuously from the lid main body section and covers the outer peripheral surface of the casing, and an outer peripheral water-stop section that stops water from entering between the lid side wall section and the outer peripheral surface of the casing.

[0010] Means 2 and a lid fixing means for preventing the lid from separating from the casing, wherein the lid fixing means guides the lid so that it covers the opening and allows the lid side wall to slide and move along the outer circumferential surface of the casing. Means 1 1 is a closing lid device according to the present invention.

[0011] Means 3 The cover body is characterized in that it has an opening through which a cable can be passed and a small cover that detachably covers the opening. Means 1 or Means 2 1 is a closing lid device according to the present invention.

[0012] Means 4 The opening is characterized in that it is provided with a cable protection material that is provided on the inner periphery of the opening and protects the cable that is passed through it. Means 3 1 is a closing lid device according to the present invention.

[0013] Means 5 The lid body is provided with a communication valve that can communicate between the outside and the casing side. Any of means 1 to 4 The closing lid device is as described above.

[0014] Means 6is a casing installation method comprising: a casing placement step of placing a casing having an open portion at its tip, which can include a recovery section inside that is recovered behind an excavator, underwater; and a closing step of covering the open portion with a lid body of a closing lid device, wherein the lid body comprises a lid main body portion that covers the open portion, a lid side wall portion that is formed continuously from the lid main body portion and covers the outer peripheral surface of the casing, and an outer peripheral water-stopping portion that stops water from entering between the lid side wall portion and the outer peripheral surface of the casing, and wherein in the closing step, the lid main body portion covers the open portion, the lid side wall portion covers the outer peripheral surface of the casing, and the outer peripheral water-stopping portion stops water from entering between the lid side wall portion and the outer peripheral surface of the casing.

[0015] Means 7 In the casing placement step, the casing is placed in water while the collection section is included therein, and in the closing step, the open section is covered with the lid of the closing lid device while the collection section is included therein. Means 6 This is a casing installation method described in .

[0016] Means 8 The closing lid device is characterized in that it includes a lid fixing means for preventing the lid from separating from the casing, and the closing step includes a lid moving step in which the lid fixing means guides the lid so that it covers the open portion and moves the lid side wall portion by sliding it along the outer peripheral surface of the casing. Means 6 or 7 This is a casing installation method described in .

[0017] Means 9 The lid body is provided with a communication valve that can communicate between the outside and the casing side, and the communication valve is kept open during the lid body moving step. Means 8 This is a casing installation method described in .

[0018] means 10is a casing installation method comprising: a casing placement step of placing a casing having an open part at its tip, which can include a recovery part therein that is recovered behind an excavator, in water; and a closing step of covering the open part with a lid body of a closing lid device, wherein the lid body comprises a lid main body part that covers the open part, a lid side wall part that is formed continuously from the lid main body part and covers the outer peripheral surface of the casing, and an outer peripheral water stopping part that stops water from flowing between the lid side wall part and the outer peripheral surface of the casing, and in the closing step, the lid main body part covers the open part, the lid side wall part covers the outer peripheral surface of the casing, and the outer peripheral water stopping part stops water from flowing between the lid side wall part and the outer peripheral surface of the casing, This casing installation method is characterized by comprising: a casing placement process in which the casing is placed in water while still containing the recovery section inside; a closing process in which the open section is covered with the lid of the closing lid device while still containing the recovery section inside the casing, the closing process comprising a lid fixing means for preventing the lid from separating from the casing; a lid moving process in which the lid fixing means guides the lid so that it covers the open section and moves the lid side wall section by sliding it along the outer peripheral surface of the casing; and a recovery process in which the recovery section is recovered to the rear of the casing after the lid moving process.

[0019] Means 11 The lid body has an opening through which a cable can be passed and a small lid that covers the opening, and the small lid is removed from the opening after the open part is covered with the lid body and before the cable is passed through the opening. Any of means 6 to 10 The casing installation method described above. [Effects of the Invention]

[0020] According to the closing lid device of the present invention, the lid body can be easily placed over the tip of the casing from the outside, so that even if the casing has a small diameter of about 600 mm and a person cannot enter the casing, the open part at the tip of the casing can be easily closed, and by providing an outer circumferential water-tight part between the lid side wall part and the outer circumferential surface of the casing, the lid body and the casing can be easily sealed off. In addition, since the open part at the tip of the casing is closed with a lid, even if a long time passes between the installation of the casing and the pulling in of the cable, the inside of the casing is prevented from remaining exposed to seawater, and barnacles and shellfish are prevented from adhering to the inside of the casing and damaging the cable.

[0021] In addition, if the lid is provided with a lid fixing means that prevents the lid from separating from the casing, and the lid fixing means guides the lid so that it covers the open portion and allows the lid side wall portion to slide and move along the outer peripheral surface of the casing, the lid can be smoothly attached to the casing and securely fixed.

[0022] In addition, since the lid main body has an opening through which the cable can be passed and a small lid that can be detachably attached and removed to cover the opening, there is no need to remove the lid body when pulling the cable into the casing; all that is required is to remove the lightweight small lid, making it easier to work underwater.

[0023] In addition, a cable protection material is provided on the inner periphery of the opening to protect the passed cable, thereby preventing the cable from being damaged by rubbing against the inner periphery of the opening when the cable is pulled into the casing through the opening.

[0024] In addition, if the cover body is provided with a communication valve that can communicate between the outside and the casing side, when fitting the cover body into the opening of the casing from the outside, by opening the communication valve to communicate between the outside and the casing side, it can be smoothly attached even if seawater or air is present on the casing side. This is particularly effective when the recovery part of the excavator is inside the casing.

[0025] According to the casing installation method of the present invention, a lid can be placed on the tip of the casing from the outside, easily sealing the open part of the casing without requiring anyone to enter the casing, thereby preventing it from being continuously exposed to seawater.

[0026] In addition, in the casing placement process, the casing is placed in water while still containing the recovery section inside, and in the closing process, the open section is covered with the lid of the closing lid device while still containing the recovery section inside the casing, and then the recovery section is recovered to the rear of the casing.This means that the lid is placed while the open section of the casing is blocked by the recovery section, thereby reducing the amount of water that enters the inside of the casing. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 2 is a cross-sectional view of a tip portion of a casing according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view of a tip portion of a casing according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view showing a state in which a blocking lid device according to an embodiment of the present invention is attached to a casing. [Figure 4] FIG. 2 is a front view of the closing lid device according to the embodiment of the present invention. [Figure 5] 10A and 10B are cross-sectional views illustrating a casing arrangement step according to an embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view of the casing tip portion in the bit removal process according to the embodiment of the present invention. [Figure 7] 10 is a cross-sectional view of the casing tip portion in the threaded rod mounting step according to the embodiment of the present invention. FIG. [Figure 8] 10 is a cross-sectional view of the casing tip portion in the lid body positioning step according to the embodiment of the present invention. FIG. [Figure 9] 10 is a cross-sectional view of the casing tip portion in a lid body moving step according to the embodiment of the present invention. FIG. [Figure 10]1 is a cross-sectional view of a casing tip portion of a recovery section of an excavator during a recovery process according to an embodiment of the present invention. FIG. [Figure 11] FIG. 10 is a cross-sectional view showing a recovery step according to an embodiment of the present invention. [Figure 12] 10A to 10C are cross-sectional views illustrating a cable installation process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings, etc. It should be noted that the present invention is not limited to the embodiments.

[0029] Figure 1 is a cross-sectional view of the tip portion of the casing according to the embodiment, Figure 2 is a front view of the tip portion of the casing according to the embodiment, Figure 3 is a cross-sectional view of the blocking lid device according to the embodiment attached to the casing, Figure 4 is a front view of the blocking lid device according to the embodiment, Figure 5 is a cross-sectional view of the casing placement process according to the embodiment, Figures 6 to 10 are cross-sectional views showing the blocking process of the tip portion of the casing according to the embodiment, Figure 11 is a cross-sectional view of the recovery process according to the embodiment, and Figure 12 is a cross-sectional view showing the cable installation process according to the embodiment. In the following description, the direction in which the excavator advances will be referred to as "forward" and the opposite direction as "backward."

[0030] In this embodiment, the present invention is applied to a casing in which a cable for transmitting power from an offshore wind turbine is installed.

[0031] The power transmission cable extending from the offshore wind turbine is installed inside a casing 2 that is installed from underwater to on land. The casing 2 is installed by a so-called jacking method, in which a sealed drilling machine 1 and a jacking pipe 10 are propelled from a starting shaft A (see Figure 5) located on land through the ground and into the water (including the seabed).

[0032] As shown in FIGS. 1 and 2, the excavator 1 comprises an excavator body 3 having a circular cross section, a pressure ring 4, a front skin plate 5, and a rear skin plate 6. The excavator body 3 is connected to the front of the pressure ring 4 in a flexible manner, and the outer circumferential surface of the excavator body 3 is covered with a front skin plate 5.

[0033] The outer peripheral surface of the pressure ring 4 is covered with a rear skin plate 6. A waterproof seal 8 is provided between the outer peripheral surface of the excavator body 3 and the inner surface of the front skin plate 5. The rear end of the front skin plate 5 and the front end of the rear skin plate 6 are connected in a flexible manner, and a bending portion seal 7 is provided at the connecting portion.

[0034] The pressure ring 4 and the rear skin plate 6 are detachably connected by a chucking device 9, and when the chucking device 9 is activated, the pressure ring 4 is integrated with the rear skin plate 6, and the excavator body 3, the pressure ring 4, the front skin plate 5 and the rear skin plate 6 excavate together. A guide member 40 is attached to the outer peripheral surface of the pressure ring 4 so as to be slidable in the axial direction relative to the inner peripheral surface of the rear skin plate 6 .

[0035] Four radially formed cutter spokes 30 are provided on the front end face of the excavator body 3, bits are provided on the surfaces of the cutter spokes 30, and a plurality of peripheral bits 31 are removably attached to the outer periphery. The outer circumferential bit 31 protrudes radially outward from the outer circumferential surface of the front skin plate 5, and is capable of drilling a hole of a diameter capable of accommodating the front skin plate 5 and the propulsion pipe 10.

[0036] A partition wall 32 is provided behind the cutter spokes 30 of the excavator body 3. To the opening of the partition wall 32, a mud feed pipe 12 and a mud discharge pipe 13 that can be extended through the pressure ring 4 are connected. A pull-out member 11 that can be extended through the pressure ring 4 is attached to the rear end of the excavator body 3.

[0037] The tip of a propulsion pipe 10 is connected to the rear end of the rear skin plate 6. The rear end of the propulsion pipe 10 can be connected to the subsequent propulsion pipe 10 in sequence. These thrust pipes 10, the front skin plate 5 and the rear skin plate 6 of the boring machine 1 constitute a cylindrical casing 2 that serves as the circumferential wall of the underground tunnel in which the power transmission cable is placed. The casing 2 is relatively thin, with an inner diameter of about 600 mm.

[0038] After being installed in the starting shaft A, the excavator 1 rotates the cutter spokes 30 to excavate the ground with the bit and the outer bit 31, and moves forward into the water by sequentially pushing the rear end of the extension pipe 10 with the pressure jack B (see Figure 5) installed in the starting shaft A.

[0039] As the excavation progresses, muddy water is supplied to the front of the partition wall 32 through the mud transport pipe 12, and the earth and sand generated by the excavation is discharged together with the muddy water through the mud discharge pipe 13 into the starting shaft A. As the excavator 1 advances, the propulsion pipe 10 is successively extended, and the drawing material 11, the mud transport pipe 12 and the mud discharge pipe 13 are extended by means of joints 11', 12' and 13', respectively.

[0040] After the excavator 1 reaches the specified destination position, i.e., after a specified length of casing 2 has been installed, the excavator body 3, pressure ring 4, excavator 11, mud transport pipe 12 and mud discharge pipe 13 contained inside the casing 2 are retrieved rearward by pulling the extraction material 11 from the starting shaft A. In this embodiment, the excavator body 3, pressure ring 4, extraction material 11, mud transport pipe 12 and mud discharge pipe 13 correspond to the recovery section that is recovered at the rear of the excavator of the present invention, and the propulsion pipe 10 and the front skin plate 5 and rear skin plate 6 of the excavator 1 correspond to the casing of the present invention.

[0041] Since an open section 20 will be formed at the tip of the casing 2 placed underwater (the tip of the front skin plate 5), the open section 20 is closed using a closing lid device 14 before the recovery section is recovered, as shown in Figures 3 and 4.

[0042] The closing lid device 14 includes a lid body 15 that covers the opening 20 of the casing 2, and a lid body fixing means 16 that prevents the lid body 15 from separating from the casing 2.

[0043] The lid body 15 comprises a lid main body portion 150 that covers the open portion 20, a lid side wall portion 151 that is formed continuously from the lid main body portion 150 and covers the outer peripheral surface of the casing 2, and an outer peripheral water-stopping portion 152 that stops water from entering between the lid side wall portion 151 and the outer peripheral surface of the casing 2.

[0044] The lid main body 150 is in the shape of a disk having a diameter slightly larger than the outer diameter of the front skin plate 5, and has a circular opening 153 formed in the lower half thereof. A ring-shaped mounting protrusion 154 is provided on the front surface of the lower part of the lid main body 150, surrounding the opening 153, and a resilient ring-shaped cable protection material 155 is attached to the inner peripheral surface of the mounting protrusion 154. A sealing material (not shown) is provided on the front end surface of the mounting protrusion 154.

[0045] Opening 153 is detachably covered with small lid 156. Small lid 156 is fixed to lid main body 150 by screwing multiple bolts 157 arranged on the outer periphery into mounting protrusions 154 from the front side, and small lid 156 can be removed by removing bolts 157.

[0046] A communication pipe 158 is installed at the top of the lid main body 150, connecting the outside (front side) with the casing 2 side (open part 20 side of the casing 2), and a communication valve 159 is provided at the outer end of the communication pipe 158, which can open and close the communication pipe 158.

[0047] The lid side wall portion 151 is formed integrally with the front skin plate 5 in parallel from the outer peripheral edge of the lid main body portion 150 toward the rear. The inner diameter of the lid side wall portion 151 is slightly larger than the outer diameter of the front skin plate 5, and a ring-shaped outer peripheral water stop portion 152 that contacts the outer peripheral surface of the front skin plate 5 is attached to the inner peripheral surface of the lid side wall portion 151.

[0048] The lid fixing means 16 comprises a plurality of threaded rods 160 (three in this embodiment) attached to the outer peripheral surface of the rear skin plate 6, a seat plate 161 attached to the outer peripheral surface of the lid side wall portion 151 of the lid 15 and through which the threaded rods 160 can be inserted, and a push-in nut 162 screwed onto the threaded rods 160.

[0049] Brackets 163, the same number as the threaded rods 160, are fixed at equal intervals in the circumferential direction to the outer peripheral surface of the rear skin plate 6. A threaded rod 160 is inserted into each bracket 163 in parallel with the axial direction of the casing 2 and so that its front end protrudes beyond the front end of the excavator body 3, and fixing nuts 164 are screwed onto the threaded rods 160 on both sides of the bracket 163. The seat plates 161 have holes for inserting the threaded rods 160, and the number of seat plates 161 provided is the same as the number of threaded rods 160. The seat plates 161 are fixed to the outer circumferential surface of the lid side wall portion 151 at equal intervals in the circumferential direction.

[0050] To attach the lid body 15 to the casing 2, threaded rods 160 are passed through the seat plates 161, and push-in nuts 162 are screwed in from the front side of the seat plates 161, so that the lid side wall portion 151 of the lid body 15 covers the outer surface of the front skin plate 5, and the lid body 15 is placed over the front end portion of the front skin plate 5, and the lid main body portion 150 covers the opening 20 on the front end surface of the casing 2. Furthermore, the outer periphery water blocking portion 152 provided on the inner periphery of the lid side wall portion 151 seals the water between the lid body 15 and the casing 2 , so that seawater does not flow into the inside of the casing 2 .

[0051] The casing 2 is installed as follows. First, as shown in Figure 5, in the casing placement process, the excavator 1 is launched from a launch shaft A drilled from the surface. A jacking pipe 10 is connected to the rear end of the rear skin plate 6 of the excavator 1, and while the cutter spokes 30 are rotated to excavate the ground in front with the bit and outer circumferential bit 31, a pressure jack B installed inside the launch shaft A pushes the rear end face of the jacking pipe 10 to move the excavator forward. As the excavator 1 advances, the jacking pipe 10, drawing material 11, mud transport pipe 12, and mud discharge pipe 13 are added, and the front end of the excavator main body 3 is advanced to a predetermined position in the water and stopped. The front skin plate 5 and rear skin plate 6 of the excavator 1 are linear bodies without being bent.

[0052] Next, as shown in Figure 6, in the bit removal step of the blocking process, a submerged diver removes the outer circumferential bit 31 that protrudes radially outward from the inner diameter of the casing 2 (front skin plate 5) (the white arrows in Figure 6 show an image of the outer circumferential bit 31 being removed from the cutter spokes 30). With the outer circumferential bit 31 removed, the recovery section of the excavator 1 can now be recovered rearward through the inside of the casing 2.

[0053] Next, as shown in Figure 7, in the threaded rod attachment step of the closing step, the diver fixes the bracket 163 to the outer peripheral surface of the rear skin plate 6 with bolts or the like, inserts the threaded rod 160 into the insertion hole provided in the bracket 163, and screws the fixing nut 164 onto the threaded rod 160 to fix the threaded rod 160 to the bracket 163. The front end of the threaded rod 160 is set to protrude far enough forward from the front surface of the cutter spoke 30 .

[0054] Furthermore, as shown in Figure 8, in the lid body positioning process of the closing process, the lid body 15 is lowered from the water, and the front end of the threaded rod 160 attached to the outer peripheral surface of the rear skin plate 6 is passed from the rear through a seat plate 161 fixed to the outer peripheral surface of the lid side wall portion 151, the lid body 15 is aligned with the casing 2, and the threaded rod 160 passed through the seat plate 161 is pushed in and the nut 162 is screwed on.

[0055] At this time, the rear end of the lid side wall portion 151 is positioned forward of the cutter spokes 30, so when aligning the seat plate 161 with the tip of the threaded rod 160, the rear end of the lid side wall portion 151 does not come into contact with the front skin plate 5, the cutter spokes 30, or the excavator body 3, and the work can be performed while concentrating solely on the alignment work.

[0056] 9, in the lid moving step of the closing step, the press nut 162 is tightened. Then, the seat plate 161 is pushed by the press nut 162 and moves toward the bracket 163, the lid 15 is guided by the threaded rod 160 and covers the front end of the casing 2, and the lid side wall 151 slides along the outer peripheral surface of the front skin plate 5 and moves rearward to cover the front end face of the casing 2. At this time, the communication valve 159 is left open so that seawater between the excavator body 3 and the cover body 15 can escape to the outside through the communication pipe 158. After the cover body 15 is placed over the front end of the casing 2, the communication valve 159 is closed.

[0057] Then, in the recovery process shown in Figures 10 and 11, first, the chucking device 9 connecting the rear skin plate 6 and the pressure ring 4 is released, and the casing 2 is separated from the recovery section contained therein, including the excavator body 3, pressure ring 4, extraction material 11, mud transport pipe 12 and mud discharge pipe 13. Next, the rear end of the extraction material 11 is pulled using a pressure jack B installed in the starting shaft A, and the extraction material 11, mud transport pipe 12 and mud discharge pipe 13 are sequentially removed while the recovery section is recovered rearward through the inside of the casing 2.

[0058] If seawater or the like remains in the casing 2 after the closing step, it is drained by an appropriate method even after the recovery step.

[0059] The open part 20 at the underwater end of the casing 2 is covered with the lid body 150, so that seawater does not newly infiltrate into the inside of the casing 2 from the open part 20 placed underwater, and it is possible to prevent barnacles, shellfish, etc. from adhering to the inside of the casing 2 due to being left exposed to seawater for a long period of time. Furthermore, since the closing process can be performed from the outside of the casing 2, this is particularly effective for a casing 2 with a small diameter that prevents workers from entering the inside.

[0060] In the cable installation process, the small cover 156 of the cover main body 150 is removed by a diver, and the cable is placed through the opening 153. Specifically, a diver connects a power transmission cable D to the front end of a wire rope C that is passed through the inside of the casing 2 in an appropriate manner, and by pulling the wire rope C from the starting shaft A as shown in Figure 12, the cable D connected to the wire rope C is pulled out to the starting shaft A through the opening 153.

[0061] In this cable installation process, a thick power transmission cable D slides inside the opening 153, but a cable protection material 155 is provided on the inner periphery of the opening 153 to prevent the cable D from rubbing against the periphery of the opening 153 and being damaged.

[0062] [Other Modifications] The present invention is not limited to the above-described embodiment, and may also include the following, for example.

[0063] In this embodiment, the cable installed inside the casing is a power transmission cable that transmits electricity from an offshore wind turbine to land, but the cable can also be any other cable that is installed underwater, such as a communication cable.

[0064] In this embodiment, the recovery section is recovered after removing the outer bit provided on the front of the cutter spoke of the excavator, but the recovery section may also be recovered after the outer bit is swung forward of the cutter spoke toward the center of rotation to reduce its diameter.

[0065] In this embodiment, the skin plates (front skin plate 5 and rear skin plate 6) provided on the excavator 1, together with the propulsion pipe 10, constitute the cable casing 2, but this is not limited to this. A configuration in which the excavator is housed inside the front end of the propulsion pipe, that is, a configuration in which the part of the front end of the propulsion pipe that houses the excavator, functions as a skin plate for the excavator body. In this case, the propulsion pipe corresponds to the casing of the present invention, and the thing housed in the propulsion pipe and collected corresponds to the collection section of the present invention.

[0066] Each technical matter in any of the embodiments including the modified examples may be applied to other embodiments to be used as examples. [Explanation of symbols]

[0067] 1. Excavator 2 Casing 20 Open area 3 Excavator body 30 Cutter Spokes 31 Periphery Bit 32 Bulkhead 4 Pressure Ring 40 Guide material 5 Front skin plate 6 Rear skin plate 7 Bend seal 8 Waterproof seal 9 Chucking device 10 Propulsion tube 11 Pulled material 12 Sludge pipe 13 Sludge drainage pipe 14 Occlusion lid device 15 Lid 150 Lid body 151 Lid side wall 152 Peripheral water stop section 153 Opening 154 Mounting protrusion 155 Cable protection material 156 Small lid 157 volts 158 Communication pipe 159 Connecting valve 16 Lid fixing means 160 threaded rod 161 Seat board 162 Press Nut 163 Bracket 164 Fixing nut A Departure shaft B Pressurized jack C. Wire rope D Cable

Claims

1. A closing lid device is capable of containing a recovery section that is recovered behind an excavator, and is disposed underwater, and includes a lid that covers an open portion of a casing having an open portion at a tip end, and a lid fixing means that prevents the lid from separating from the casing, The lid body is a lid main body portion that covers the opening; a lid sidewall portion formed continuously from the lid main body portion and covering an outer peripheral surface of the casing; an outer periphery water stopping portion that stops water between the lid side wall portion and the outer periphery surface of the casing, The lid fixing means is capable of guiding the lid so that it covers the opening and of sliding the lid side wall along the outer circumferential surface of the casing. A closing lid device characterized by:

2. A blocking lid device that can include a recovery section therein that is recovered behind an excavator, and that is disposed underwater and has a lid body that covers an open section of a casing having an open section at a tip thereof, The lid body is a lid main body portion that covers the opening; a lid sidewall portion formed continuously from the lid main body portion and covering an outer peripheral surface of the casing; an outer periphery water stopping portion that stops water between the lid side wall portion and the outer periphery surface of the casing, The lid body is provided with a communication valve that can communicate between the outside and the casing side.

3. 3. The closing lid device according to claim 1, wherein the lid body comprises an opening through which a cable can be passed, and a small lid that detachably covers the opening.

4. 4. The closing lid device according to claim 3, wherein the opening is provided with a cable protector provided on an inner periphery of the opening to protect a cable passed through the opening.

5. a casing placement step of placing a casing having an open portion at a tip end thereof, the casing being capable of including a recovery portion therein that is recovered at the rear of the excavator, into water; A casing installation method including a closing step of covering the open portion with a lid body of a closing lid device, The lid body is a lid main body portion that covers the opening; a lid sidewall portion formed continuously from the lid main body portion and covering an outer peripheral surface of the casing; an outer periphery water stopping portion that stops water between the lid side wall portion and the outer periphery surface of the casing; Equipped with In the closing step, the lid main body covers the open portion, the lid side wall covers the outer peripheral surface of the casing, and the outer peripheral water stopping portion stops water between the lid side wall and the outer peripheral surface of the casing, the closing lid device includes a lid fixing means for preventing the lid from separating from the casing, The closing step includes a lid moving step in which the lid fixing means guides the lid so that it covers the opening and moves the lid side wall by sliding it along the outer peripheral surface of the casing. A casing installation method characterized by:

6. In the casing placement step, the casing is placed in water while the collection section is still included therein, In the closing step, the open portion is covered with the lid of the closing lid device while the collection portion is kept inside the casing.

6. The casing installation method according to claim 5, wherein:

7. a casing placement step of placing a casing having an open portion at a tip end thereof, the casing being capable of including a recovery portion therein that is recovered at the rear of the excavator, into water; A casing installation method including a closing step of covering the open portion with a lid body of a closing lid device, The lid body is a lid main body portion that covers the opening; a lid sidewall portion formed continuously from the lid main body portion and covering an outer peripheral surface of the casing; an outer periphery water stopping portion that stops water between the lid side wall portion and the outer periphery surface of the casing; Equipped with In the closing step, the lid main body covers the open portion, the lid side wall covers the outer peripheral surface of the casing, and the outer peripheral water stopping portion stops water between the lid side wall and the outer peripheral surface of the casing, the recovery unit includes an excavator body whose outer circumferential surface is inscribed between the excavator body and the inner surface of the casing via a waterproof seal; In the casing placement step, the casing is placed in water while the collection section is still included therein, In the closing step, the opening is covered with the lid of the closing lid device while the collection section is included inside the casing, and a recovery step of recovering the recovery section to the rear of the casing after the closing step. A casing installation method characterized by:

8. the lid body includes a communication valve that can communicate between the outside and the casing side, 7. The casing installation method according to claim 5, wherein the communication valve is kept open during the lid moving step.

9. a casing placement step of placing a casing having an open portion at a tip end thereof, the casing being capable of including a recovery portion therein that is recovered at the rear of the excavator, into water; A casing installation method including a closing step of covering the open portion with a lid body of a closing lid device, The lid body is a lid main body portion that covers the opening; a lid sidewall portion formed continuously from the lid main body portion and covering an outer peripheral surface of the casing; an outer periphery water stopping portion that stops water between the lid side wall portion and the outer periphery surface of the casing; Equipped with In the closing step, the lid main body covers the open portion, the lid side wall covers the outer peripheral surface of the casing, and the outer peripheral water stopping portion stops water between the lid side wall and the outer peripheral surface of the casing, In the casing placement step, the casing is placed in water while the collection section is still included therein, In the closing step, the opening is covered with the lid of the closing lid device while the collection section is included inside the casing, the closing lid device includes a lid fixing means for preventing the lid from separating from the casing, The closing step includes a lid moving step in which the lid fixing means guides the lid so that it covers the opening and moves the lid side wall by sliding it along the outer peripheral surface of the casing, and a recovery step of recovering the recovery unit to the rear of the casing after the lid body moving step. A casing installation method characterized by:

10. the lid body includes an opening through which a cable can be passed and a small lid that covers the opening, After the opening is covered with the lid and before a cable is passed through the opening, the small lid is removed from the opening. The casing installation method according to any one of claims 5 to 9.

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