JP2006249685A - Cofferdam construction method for underwater structure, and structure for cofferdam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an influence of an external force and manufacturing costs and enable reuse, by reducing the outside dimensions of a working caisson. <P>SOLUTION: The working caisson 10, which is composed of an annular steel shell formed by preassembling a plurality of stiffening-plate-structure pressure-resistant blocks 12, is floated and towed to a construction site in a state wherein a detachable buoyancy body 40 is mounted on the outer periphery of the working caisson 10, and installed in such a manner as to enclose a working object 8. After the removal of at least a part of the buoyancy body, the inside of the working caisson is drained, so that the working object can be fixed by a difference between the water pressure of the inside of the steel shell and that of the outside thereof, and so that a working space can be formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a temporary closing method for securing a dry working space in repairing and reinforcing work of underwater structures such as bridge piers constructed underwater, and a temporary closing structure for the same.

  The need for seismic reinforcement is increasing due to aging repairs and revision of seismic design standards for bridge piers constructed in the sea or rivers. In such repair and reinforcement work for underwater structures, it is indispensable to provide a dry working environment without water around the target structure for the purpose of ensuring quality and safety.

  For temporary closing to perform dry work, a method of placing steel sheet piles and steel pipe sheet piles around as a water blocking wall was used, but if there is a restriction on the use of upper space such as bridge piers, It was pointed out that the sheet pile was difficult to lay and the construction period was long.

  In order to solve this problem, as represented by Patent Documents 1 to 6, using a work box made of a double steel shell capable of floating towing, after installing so as to surround the work object (structure), Water is poured into a double steel shell and set, and water is stopped using a water stop jig provided on the work object and the bottom of the work box or on the side of the bottom. Is used.

Japanese Patent No. 3024932 Japanese Patent No. 30659927 Japanese Patent No. 3330018 JP 2002-201649 A Japanese Patent No. 3379391 Japanese Patent No. 3387436

However, the above prior art has the following problems. That is,
(1) Since the work box itself has a double steel shell structure to make it a buoyant body for floating towing, the outer dimensions of the work box are increased, and the pressure receiving area for tidal and wave forces is increased. The number of cut beam materials to be increased. Alternatively, when the outer diameter is reduced, the internal work space is narrowed and the work efficiency is reduced.

  (2) Also, because of the double steel shell structure, the number of manufacturing steps increases, and the manufacturing cost of the work box increases.

  (3) It is necessary to attach a water stop jig to the work object such as a pier footing in advance with a certain degree of accuracy in order to stop the water at the bottom.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to reduce the external dimension of the work box to reduce the influence of external force and the manufacturing cost, and to enable reuse.

  In the present invention, a work box made of an annular steel shell having a pressure-receiving widening part attached to the outer periphery at the bottom is installed so that a removable buoyancy body is attached to the outer periphery to float on the site and surround the work object. After removing at least a part of the buoyant body, the inside of the work box is drained, fixed to the work object by the vertical component of the water pressure difference of the pressure receiving widening part, and water is stopped to form a work space. The above-mentioned problem is solved.

  The work box is made of an annular steel shell in which a plurality of stiffening plate structure pressure-resistant blocks are assembled in advance, or a partial steel shell divided into two or more in the circumferential direction.

  Further, the pressure-receiving widened portion has an elastic sealing material for water sealing at the bottom, or a waterproof skirt in which, for example, an elastic sealing material is coated on the inner surface, or both of them, and a work object by prior underwater work. This minimizes the installation work of the water stop jig. The waterproof skirt having the elastic seal material or the elastic seal material coated on the inner surface is drained from the inside of the work box and is brought into close contact with and pressurized by the vertical component of the water pressure inside and outside the work box. Maintains stability and watertightness against external forces.

  Further, the pressure-receiving widened portion includes a replaceable water-stop box cross-sectional member so that the water-stop performance can be easily recovered when the work box is reused.

  In addition, the buoyancy body is a float part made of a double steel shell provided in the submerged part, a plurality of, for example, steel pipe columns provided on the upper part, and a steel plate provided at the top, for example, a steel plate. Alternatively, by providing a work table made of an extended metal, a grating, or the like, the action force against the flow or waves during the installation of the work box is reduced.

  In addition, the buoyancy body is equipped with a hoisting and lowering device for installing and sinking a work box on the work object at the top of the flow and the part made of a double steel shell that can be divided into two or more parts. It is.

  In addition, the work box and the buoyancy body can be formed into a planar shape such as a circle, an oval shape, a rectangle, a polygon, etc. by inserting a water-stopping material into a joint surface and fastening with a fixing tool. It is a thing.

  The present invention also includes a work box made of an annular steel shell formed by pre-assembling a plurality of stiffening plate structure pressure-resistant blocks, or a work box made of partial steel shells divided into two or more in the circumferential direction, and detachable on the outer periphery thereof. And a buoyancy body for towing and installing the work box, to provide a temporary closing structure.

  The work box and the buoyant body are divided into two or more units in a floating state in the vicinity of the work object, and an opening / closing mechanism that can be closed after installation on the work object (for example, a hinge mechanism provided on the buoyancy body). It is provided.

  According to the present invention, a work box made of an annular steel shell in which a stiffening plate structure pressure-resistant block is pre-assembled and a buoyancy body for floating towing / on-site installation are separated, and the buoyancy body is removed after the work box is installed. As a result, the outer dimensions of the work box can be reduced as compared with the buoyancy body integrated work box according to the prior art, so that the influence of external force acting on the work box can be minimized. Furthermore, the production cost of the work box can be reduced.

  In addition, since the buoyancy body is separated from the work box, it can be reused after one work box is installed, which is economical in a plurality of work box installation operations.

  In particular, when the buoyant body is a semi-submersible type and a work platform is mounted on the top, it can be used as a work scaffold when the work box is installed, thereby improving the workability of work on site.

  In addition, when an elastic sealant or waterproof skirt attached in advance to the widened part of the work box bottom is used, the water stop between the work box objects is caused by the vertical component of the pressure difference inside and outside the water stop part due to drainage in the work box. This makes it possible to significantly reduce the prior underwater work required in the prior art.

  In addition, when a semicircular cross section and a straight section are used as a stiffening plate pressure block and a buoyant body, it is possible to easily cope with work objects having various cross sectional shapes by fastening them as necessary. .

  Below, a 1st embodiment of the present invention about the case where a work subject has a circular section is described in detail along a drawing.

  FIG. 1 is a front view showing a state of towing the work box and buoyant body of the present invention to the field, and FIG. 2 is a plan view showing the state when the work box is installed, and (B) seen from the front. FIG. 3 to 5 are front views showing the construction procedure from the assembly work on the land side of the work box to the field installation, and FIGS. 6 and 7 are pre-worked for water stoppage between the work box and the work object. 8 is a half cross-sectional view seen from the front for explaining a water-stopping method using a waterproof skirt coated with a film-like elastic seal for waterproofing and an elastic seal attached to the bottom widened portion of the box. FIG. It is an expanded sectional view which shows the detail of the attachment structure to the work box widening part of a waterproof skirt.

  The work box 10 used for the temporary deadline of the present invention is configured to use a pressure-resistant block 12 (see FIG. 2 (B)) composed of a plurality of stiffening plates for land (see FIG. 3 (A)) or floating towing / installation. This is an annular steel shell structure assembled inside the buoyancy body 40 (see FIG. 3B), inserted with a water stop material 13 such as a rubber sheet on the joint surface between the blocks 12, and then fastened with bolts. 4 (D) and (E), the outer periphery is supported in water by a detachable buoyancy body 40 as shown in FIG. The work box 10 and the buoyancy body 40 are assembled in an annular shape as shown in FIG. 3C until arrival at the site to ensure stability during towing.

  After arrival at the site, in order to attach to the work object 8, as shown in FIG. 2, the fan mechanism 44 attached to the buoyancy body 40 opens in a fan shape (see FIG. 4 (F)) and surrounds the work object 8. After that, the hinge mechanism 44 is closed again at the closing portions 15 and 45 to form an annular structure (see FIG. 5G).

  The buoyancy body 40 is a semi-submersible type in which the float 42 can be submerged in order to ensure stability during towing and minimize the influence of the tide level. A work table 48 having a structure that is difficult to receive water pressure, such as expanded metal or grating, is installed at the top end with the support 46 as a support column, thereby facilitating work box installation work in the field.

  3 to 5 show the construction process from assembly of the work box 10 to installation at the site. In FIG. 3 (A), the work box 10 is assembled on the land portion only at the first stage of the pressure-resistant block 12, and after assembling in an annular shape, as shown in FIG. 3 (B), the buoyant body 40 moored on the quay. It shows the process of inserting into the inner space of the sequel and making a large assembly on the water. This is because a large set of work boxes 10 on the land section increases the weight and requires a large lifting machine 60, but if the lifting machine 60 has a head and capacity, the whole is large on land. It can also be assembled and mounted on the buoyancy body 40 by lump-up.

  In order to ensure stability during towing to the site, as shown in FIGS. 3 (C) and 4 (D), the work box 10 and the buoyant body 40 are assembled in an annular shape and floated towed by the towed carrier ship 62. The

  After the work box 10 and the buoyancy body 40 arrive at the site, as shown in FIG. 4 (E), the work box 10 and the buoyancy body 40 are fixed to the tip of the towed carrier ship 62 as shown in FIG. As shown, after opening using a hinge mechanism 44 provided in the buoyancy body 40 and installing so as to surround the work object 8, it is closed again, and a waterproof rubber is inserted into the work box closing portion 15. To form an annular structure as shown in FIG.

  After installing the work box 10 and the buoyancy body 40 so as to surround the work object 8, as shown in detail in FIG. 6 (A), water 6 is poured into the float portion 42 of the buoyancy body 40, and FIG. As shown, it sinks until it reaches the bottom of the work object 8. Here, the contact surface 9 (see FIG. 2 (B)) of the work box 10 of the work object 8 is previously cleaned of sediment, etc. so that the bottom water stop is completely performed.

  As shown in FIG. 6 (B), after confirming the settling to a predetermined position, the water 6 poured into the work box 10 is drained, and as shown in FIG. 7 (C), the work box 10 generated in the bottom widened portion 16. Due to the difference in water pressure inside and outside, the elastic sealing material 18 or the waterproof skirt 20 attached to the widened portion 16 is compressed to enhance the water stop effect.

  FIG. 8 shows the details of the structure of the widened portion 16 at the bottom of the work box and the method of attaching the elastic sealing material 18 and the waterproof skirt 20 to the widened portion 16. In this embodiment, the protrusion 11 having a box cross-sectional shape is provided in advance along the bottom of the work box, and an annular water stop with an opening at the bottom for attaching the elastic sealing material 18 and the waterproof skirt 20 to the tip thereof. The box cross-section member 22 is joined with a bolt 24. By using this method, when the work box 10 is repeatedly used, the water stop performance of the work box 10 can be recovered by replacing only the water stop box cross-section member 22.

  As shown in detail in FIG. 8A, the elastic seal material 18 is a backup material for forming an elastic seal material so that a predetermined height of the elastic seal material can be secured in the lower opening of the water-stopping cross-section member 22. After mounting 26, the elastic sealing material 18 is injected from the upper opening 23 of the water blocking cross-section member 22, and after the solidification, the backup material 26 is removed. As shown in FIG. The elastic sealing material 18 is fixed by filling mortar 28 in the upper space of 18.

  Further, as shown in detail in FIG. 8B, the waterproof skirt 20 is fastened to the side surface of the water-stopping box cross-section member 22 with a bolt 34 via a mounting plate 32. As shown in detail in FIG. 9, an elastic sealing material 36 is applied to the inner surface of the waterproof skirt 20 in the form of a film.

  In addition, in FIG. 8, although the situation at the time of using both the elastic sealing material 18 and the waterproof skirt 20 is shown, if the surface state of the work object 8 is good, the water-stopping effect is sufficient by using only one of them. can get.

  In the above description, the cross section of the work object 8 is circular. However, when the cross section of the work object 8 is oval or rectangular, as in the second embodiment shown in FIGS. 10 to 11, A straight work box pressure-resistant block 70 is inserted between the semicircular parts of the circular section work box 10, and a linear buoyant body 72 is also inserted into the buoyancy box 30. It is possible to easily cope with it by tightening.

  In the above embodiment, a method is shown in which a work box is assembled in advance into an annular steel shell, divided into two divided units in a floating state after towing in the vicinity of the work object, and after being installed on the work object, it is closed using an opening / closing mechanism. However, this method is effective for the construction of a relatively small work box because the work box is in a floating state and the buoyancy body is opened and closed. When the dimensions of the work box are large, the opening / closing load due to water resistance increases when opening and closing in a floating state, and a large-scale opening / closing mechanism is required, and special considerations are required to ensure the stability of the structure during construction. Problems such as necessity arise, and the effect of the invention is reduced.

  An embodiment of the present invention when the work box size is large will be described below for a rectangular cross-section work box.

  FIGS. 13 and 14 show third and fourth embodiments of the working box 10 and the buoyant body 40 ′ that can accommodate a large-sized rectangular cross section. In the third embodiment shown in FIG. 13, the buoyancy body 40 ′ has a two-part structure at the same positions 15 and 45 as the work box 10.

  In the present invention in which the buoyancy box and the work box are separated from each other, unlike the work box and the buoyancy box integrated structure in the prior art, the buoyancy box does not need to be a continuous structure. A dimension and shape that gives the minimum buoyancy may be used, and a plurality of buoyancy bodies having good workability during land transportation and launching can be obtained as in the fourth embodiment shown in FIG. In FIG. 14, the member 90 installed inside the work box 10 is a reinforcing member added because the buoyancy box has a split structure, so that it is necessary to reinforce the strength of the work box during towing. Even after installation on the object, it functions as an internal beam.

  In this case, it is necessary to perform water injection and draft adjustment in synchronism with the installation of the work box in the buoyancy body at the same time, which impairs workability and safety at sea. In the present embodiment, the winch 80 is mounted on the top of the buoyant body, and the wire rope 81 of the winch is connected to the hanging bracket 82 attached to the lowermost stage of the work box via the roller 83, and the work is performed by winding and lowering the winch. By adjusting the vertical position of the box, it is possible to safely increase the construction speed of the sinking work.

  FIG. 15 shows a work procedure of the fourth embodiment using the large-sized rectangular cross-section work box. As the working box size increases, the pressure block size also increases and the weight of one block increases. Therefore, the size of assembling is reduced as much as possible, and the required capacity of the hoist required for onshore work is kept small. Is economical construction. In this embodiment, as shown in FIG. 15 (A), the floating towing work box and buoyant body are divided into two parts, and the water blocking material 17 is buried in the bottom of the lowermost stage, and then the pressure-resistant block one by one in the height direction. 12 is assembled. Each time the assembly of one block 12 is completed, the buoyancy body 40 ′ is suspended in a state of being suspended on a wire rope 81 wound around a winch 80 installed at the top end of a half-section buoyancy body 40 ′ moored on a quay by a lifting machine 60. And assemble the half of the work box offshore in front of the quay. At this time, it is desirable to support the side surface by the tow carrier 62 in order to ensure the overall stability.

  FIG. 16 (C) shows that after the large assembly of the half section of the work box block 12 is completed, the integrated work box half section 10 and the buoyancy body half section 40 ′ are fixed to the tip of the carriage 62 in a floating state. This shows the situation of floating towing near the work object. The remaining half-section work box is also assembled in large scale according to the above procedure and then floated to the site by another trolley.

  FIG. 16D shows a state in which the work box 10 and the buoyancy box 40 ′ assembled by half sections and floated to the site are opposed to each other with the work object 8 interposed therebetween. After performing the planar positioning of the mounting position of the work box, as shown in FIG. 16 (E), the work box 10 and the buoyancy box 40 ′, which are opposed to each other in half section, are surrounded by the carriage 62 with the work object 8. After inserting a water sealing material into the work box closing surface 15 in a floating state, the work box is fastened and integrated with a bolt or the like to form an annular work box.

  FIG. 17 (F) shows that after the work box is closed and integrated into a ring shape, the winch 80 installed at the top of the buoyant body is lowered, and the wire rope 81 having the tip coupled to the lowermost stage of the work box 10 is vertically lowered. A state in which the bottom water-stop sealing material 18 to the water-stop skirt 20 of the work box 10 are installed on the footing 9 of the work object 8 by extending is shown.

  FIG. 17G shows that after confirming that the work box 10 has settled on the footing 9, the inside of the work box is drained, and the bottom part is pressed by pressing the water stop sealing material or the water stop skirt due to the water pressure difference inside and outside the work box. The state where water stoppage is ensured and the work inside the work box is possible. At this stage, the buoyancy box 40 'may be detached from the work box 10 and towed, but a part of the buoyancy body 40 "is left in the work box 10 as shown in FIG. It can also be used as a floating pier.

The front view which shows the state at the time of towing to the field of the work box and buoyancy body of 1st Embodiment of this invention Similarly, (A) Plan view and (B) Half sectional view seen from the front showing the state when the work box is installed Similarly, a front view showing a part of the construction procedure from assembly work on the land of the work box to field installation Similarly, a front view showing another part of the construction procedure from assembly work to on-site installation on the land of the work box A front view showing the rest of the construction procedure from assembly work on the land of the work box to field installation Similarly, a half-sectional view seen from the front to explain how to stop water between the work box and work object Similarly, a half-sectional view seen from the front to explain how to stop water between the work box and work object Similarly, an enlarged cross-sectional view showing the details of the structure for attaching the waterproof seal and waterproof skirt to the work box widening section Sectional view showing the configuration of the waterproof skirt A half sectional view from the front showing a second embodiment of the present invention when the work object has an oval or rectangular cross section Same top view Same side view (A) Front view, (B) Plan view, and (C) Side view showing a third embodiment of the present invention that can accommodate a large-sized rectangular cross section. (A) Front view, (B) Plan view, and (C) Side view showing the fourth embodiment. Similarly, a front view showing a part of the construction procedure of the fourth embodiment Similarly, the front view which shows a part of construction procedure of 4th Embodiment Similarly, the front view which shows the remainder of the construction procedure of 4th Embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 8 ... Work object 10, 70 ... Work box 12 ... Pressure-resistant block 13 ... Water stop material 15, 45 ... Closure part 16 ... Widening part 17 ... Water stop material 18, 36 ... Elastic sealing material 20 ... Waterproof skirt 22 ... Water stop Box section member 40, 40 ', 40 ", 72 ... Buoyant body 42 ... Float part 44 ... Hinge mechanism 46 ... Steel pipe column 48 ... Work table 60 ... Lifting machine 62 ... Towing carrier 71, 73 ... Connecting part 80 ... Winch 81 ... Wire rope 82 ... Hanging bracket 83 ... Roller 90 ... Reinforcing member

Claims (9)

  A work box consisting of a ring-shaped steel shell with a pressure-receiving widening part attached to the outer periphery is attached to the outer periphery of the work box, floated to the site, and installed so as to surround the work object. Underwater structure characterized by forming a work space by draining the inside of the work box after removing at least a part, adhering to the work object by the vertical component of the water pressure difference of the pressure receiving widening part, and stopping water Temporary deadline construction method.   2. The temporary closing method according to claim 1, wherein the work box is made of an annular steel shell formed by assembling a plurality of stiffening plate structure pressure-resistant blocks in advance, or a partial steel shell divided into two or more in the circumferential direction. .   The temporary closing method according to claim 1, wherein the pressure-receiving widened portion has at least one of a bottom water-stopping elastic sealing material and a waterproof skirt.   The temporary closing method according to claim 1, wherein the pressure-receiving widened portion includes a replaceable water-stop box cross-section member.   The buoyancy body includes a float portion made of a double steel shell provided in a submerged portion, a plurality of support columns provided in the upper portion thereof, and a work table provided in the top end thereof, and the work box is being installed. The temporary closing method according to any one of claims 1 to 4, wherein an acting force on the flow of water and waves is reduced.   The buoyancy body is equipped with a hoisting and lowering device for installing and sinking a work box on a work object at the top end of the flow and part made of a double steel shell that can be divided into two or more parts. The temporary closing method according to any one of claims 1 to 5.   The work box and the buoyancy body can be formed into a planar shape such as a circle, an oval shape, a rectangle, or a polygon by inserting a water blocking material into a joint surface and fastening the blocks with a fixing tool. The temporary closing method according to any one of claims 1 to 6, characterized in that: A work box made of an annular steel shell formed by pre-assembling a plurality of stiffening plate structure pressure-resistant blocks, or a work box made of partial steel shells divided into two or more in the circumferential direction;
A buoyant body for towing and installing the work box, detachable from the outer periphery;
A temporary cutoff structure characterized by comprising:   9. The work box and the buoyant body are divided into two or more units in a floating state in the vicinity of the work object, and an open / close mechanism that can be closed after being installed on the work object is provided. The structure for temporary deadlines as described.

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