Bottom slab structure of hybrid caisson

Abstract

To provide a bottom slab structure of a hybrid caisson using rubber mats capable of satisfying a required friction increase function to secure covered thickness of concrete.SOLUTION: A bottom slab structure 10 of a hybrid caisson is installed on a rubble mound composed of steel shells 12 and reinforced-concrete 13 covering the steel shells 12, and is provided with a rubber mat 15 securing a covered thickness B by reinforcement-concrete 13 between the steel shells 12 and itself through suppression of shrinkage of load by increasing friction with the rubble mound arranged on a lower surface of a plurality of bottom slab members 16 supporting weight load through steel shell support members 14 supporting the steel shells 12, wherein shrinkage limit members 17 are buried in the rubber mat 15, the shrinkage limit members having a thinner thickness than a thickness T of the rubber mat 15 by a shrinkage amount allowed for the support load applied per member of the steel shell support members 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bottom plate structure of a hybrid caisson. [Background technology]

[0002] Hybrid caissons, which are used to construct embankments such as breakwaters, quays, and revetments, mainly have a steel shell covered with reinforced concrete, and are installed on a rubble mound constructed of stone or other materials on the seabed. The base structure of the hybrid caisson is required to support the load of the steel shell, ensure the thickness of the reinforced concrete covering the base, and ensure the frictional force between the rubble mound and the hybrid caisson to increase stability against sliding. For this reason, a mat to increase friction is placed on the bottom surface of the hybrid caisson as part of the base structure of the hybrid caisson.

[0003] Examples of mats for increasing friction include the asphalt mat disclosed in Patent Document 1 and the rubber mat disclosed in Patent Document 2. The asphalt mat and rubber mat for the hybrid caisson are constructed on the surface plate of the hybrid caisson production yard, and support fittings made of bent strips are embedded in the asphalt mat to support the load of the steel shell of the hybrid caisson, and the rubber mat is made to a thickness and size that limits the amount of settlement to an allowable level for the support load applied, thereby ensuring the cover of reinforced concrete on the bottom slab of the hybrid caisson. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-146748 A [Patent Document 2] JP 2018-059361 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the bottom slab structure disclosed in Patent Document 1, in which support fittings are embedded in the asphalt mat to support the load of the steel shell, multiple support fittings capable of supporting the load of the steel shell must be embedded, which increases the number of construction steps and construction costs. Furthermore, when the rubber mat disclosed in Patent Document 2 is used, the sinking amount of the rubber mat increases in response to the load of the steel shell, resulting in insufficient covering, and a hard rubber mat with a small sinking amount does not provide the necessary increase in friction.

[0006] The present invention has been made in consideration of the problems of the conventional technology described above, and aims to provide a bottom slab structure of a hybrid caisson using a rubber mat that satisfies the necessary friction-increasing function and can ensure the covering thickness of the concrete. [Means for solving the problem]

[0007] In order to achieve the above object, the bottom plate structure of the hybrid caisson according to the present invention is as follows: A hybrid caisson base structure in which a hybrid caisson consisting of a steel shell and reinforced concrete covering the steel shell is installed on a rubble mound, a plurality of bottom plate members that support the load of the steel shell via a plurality of steel shell support members that support the bottom surface of the steel shell; a rubber mat provided on the underside of the bottom plate member to increase friction with the riprap mound and suppress the amount of contraction of the steel shell due to the load, thereby ensuring a covering thickness of the reinforced concrete between the bottom surface of the steel shell and the rubber mat; A shrinkage control member is embedded in the rubber mat on the lower surface of the bottom plate member below the steel shell support member, the shrinkage control member being thinner than the thickness of the rubber mat by an amount corresponding to an allowable shrinkage amount due to a support load applied to each of the steel shell support members. It is characterized by:

[0008] It is preferable that a plurality of the shrinkage restricting members are embedded in the rubber mat so as to make the amount of shrinkage uniform.

[0009] It is preferable that the bottom plate member and the rubber mat are fixed together and attached to the steel shell support member.

[0010] It is preferable that a rubber mat for increasing friction having a retractable and erectable anchor member is provided under the bottom surface of the steel shell other than where the bottom plate member is disposed. The rubber mat referred to here includes the rubber mat portion. Effect of the Invention

[0011] According to the present invention, it is possible to provide a bottom slab structure of a hybrid caisson using a rubber mat that satisfies the required friction-increasing function and ensures the covering thickness of concrete. [Brief description of the drawings]

[0012] [Figure 1] This is an embodiment of the bottom slab structure of a hybrid caisson of the present invention, in which the structure is placed in the center of a rubber mat, (a) is a cross-sectional view taken along line AA in (b), and (b) is a partially enlarged cross-sectional view. [Diagram 2] FIG. 1A shows a plan view of a rubber mat according to an embodiment of the present invention, and FIG. [Diagram 3] FIG. 2A shows a partial plan view and FIG. 2B shows a partial cross-sectional view of an embodiment of the present invention in which the rubber mat is disposed at a joint portion of the rubber mat. [Figure 4] FIG. 1 illustrates one embodiment of the present invention, in which (a) is an external perspective view of a hybrid caisson, and (b) is a partially enlarged cross-sectional view. [Diagram 5] FIG. 1A is a schematic perspective view of a process for installing a friction-increasing mat, and FIG. 1B is a schematic perspective view of an installed state of a steel shell support member, showing a manufacturing process according to one embodiment of the present invention. [Figure 6]1A is a plan view and a perspective view of a process for installing a friction-enhancing mat, and FIG. 1B is a plan view and a perspective view of an installed state of a steel shell support member, showing a manufacturing process according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the bottom slab structure of a hybrid caisson of the present invention will be described in detail with reference to Figs. 1 to 5 of the drawings. A hybrid caisson 11 to which the hybrid caisson bottom slab structure 10 of the present invention is applied is constructed by covering a steel shell 12 with reinforced concrete 13, for example, as shown in FIG. As shown in FIG. 4, in order to ensure a covering thickness (cover) B of the reinforced concrete 13 when pouring the reinforced concrete 13, during production, the bottom surface 12a of the steel shell 12 is supported at intervals via a plurality of columnar steel shell support members 14, for example, on a production yard base plate 1 of the hybrid caisson 11. This hybrid caisson 11 is installed on a rubble mound 3 formed of rubble or the like on the seabed ground 2, and a friction-increasing mat 20 made of a rubber mat or the like is attached between the hybrid caisson 11 and the rubble mound 3. The friction-increasing mat 20 is provided with a rubber mat 15 portion as an integrated support area corresponding to a plurality of steel shell support members 14 that support the load of the steel shell 12. The rubber mat 15 portion that supports this load is a convenient portion (display portion) for dividing the area of ​​the friction-increasing mat 20. In other words, in the bottom slab structure 10 of the hybrid caisson 11, multiple friction-increasing mats 20 are arranged in a front-to-back and left-to-right combination over the entire surface of the bottom slab of the hybrid caisson 11, and the steel shell support member 14 portion becomes the rubber mat 15 portion.

[0014] In the bottom slab structure 10 of the hybrid caisson of the present invention (hereinafter, simply referred to as the bottom slab structure 10), a plurality of bottom plate members 16 that support the load of the steel shell 12 via a plurality of steel shell support members 14 that support the bottom surface 12a of the steel shell 12 are provided in the rubber mat 15 portion. A friction-increasing mat 20 is provided on the underside of the bottom plate member 16, which has a rubber mat 15 portion that increases friction with the rubble mound 3, suppresses the amount of shrinkage t due to the load of the steel shell 12, and ensures a covering thickness B of the reinforced concrete 13 between the bottom surface 12a of the steel shell 12 and the bottom surface 12a of the steel shell 12. A shrinkage-restricting member 17 (having a height Tt) is embedded in the rubber mat 15 portion on the underside of the bottom plate member 16 below the steel shell support members 14, and has a height lower than the thickness T of the rubber mat 15 portion by the amount of shrinkage t allowed for the support load applied to each steel shell support member 14 (see Figs. 1 to 4). That is, a bottom plate member 16 is arranged corresponding to the steel shell support member 14 of the steel shell 12 of the hybrid caisson 11, and the steel shell 12 is supported via the steel shell support member 14 on the bottom plate member 16 located on the upper surface of the rubber mat 15 portion in which the shrinkage control member 17 is embedded.

[0015] The friction-increasing mat 20 comprising the rubber mat 15 portion is attached in advance during the manufacture of the hybrid caisson 11, and the amount of shrinkage t of the rubber mat 15 portion due to the load of the steel shell 12 applied via the steel shell support member 14 and the bottom plate member 16 is restricted by the shrinkage restriction member 17, so that the amount of shrinkage t of the rubber mat 15 portion is set to, for example, 2 to 5 mm or less while maintaining the thickness T of the friction-increasing mat 20. The friction-increasing mat 20 attached to the hybrid caisson is in a laid state when the hybrid caisson 11 is installed on the rubble mound 3. By doing this, even when the load is supported by the rubber mat 15 portion of the friction-increasing mat 20, large sinking due to the load of the steel shell 12 applied through the steel shell support member 14 is suppressed, the covering thickness (cover) B of the reinforced concrete 13 on the steel shell 12 is ensured, and the friction-increasing function between the hybrid caisson 11 and the rubble mound 3 is secured, preventing distortion of the hybrid caisson 11 itself and tilting due to shrinkage of the rubber mat 15 portion during manufacture.

[0016] The steel shell support member 14 may be made of steel, or may be made of a non-metallic material such as a resin material or mortar to prevent rust, or may be a combination of steel and a non-metallic material; there are no particular limitations on the material or structure.

[0017] The steel shell support member 14 is a member for ensuring a covering thickness B of the reinforced concrete 13 between the bottom plate member 16 and the steel shell 12 in cooperation with the bottom surface 12a of the steel shell 12, and supporting the load of the steel shell 12. The steel shell support member 14 is disposed at the center of the upper surface of the bottom plate member 16. The steel shell support member 14 is made of steel, for example, an H-shaped steel, and is disposed in an H-shape in a plan view to support the load of the steel shell 12. The steel shell support member 14 is not limited to H-shaped steel, and may be other shaped steel or a welded structure as long as it can withstand the load. Although not shown, a bottom plate material may be installed at the contact part between the steel shell support member 14 and the bottom plate member 16 in order to reduce the impact during installation.

[0018] The friction-increasing mat 20 and the integral rubber mat 15 of the bottom slab structure 10 are made of hard rubber, for example, natural rubber or synthetic rubber containing carbon black, which has durability such as resistance to aging, seawater, oil, and abrasion, or a vulcanized mixture of these, and the raw material composition and vulcanization conditions are adjusted. Recycled rubber may also be used. At least the rubber mat 15 is designed so that the amount of shrinkage t of the rubber mat 15 in response to the load applied to each steel shell support member 14 is suppressed to within, for example, 2 to 5 mm. For this reason, a shrinkage restricting member 17 for restricting the amount of shrinkage t is embedded in the rubber mat 15 portion. The shrinkage restricting member 17 is, for example, a round steel bar, and is embedded with the central axis of the cylinder oriented vertically. That is, the shrinkage restricting member 17 is embedded in the rubber mat 15 with its height lowered by the allowable amount of shrinkage t relative to the thickness T of the rubber mat 15. The embedding position relative to the thickness T of the rubber mat 15 can be any position, and for example, as shown in Fig. 2, it can be embedded with a space of t / 2 above and below, or as shown in Fig. 3, it can be embedded with a space of t on the upper side, as long as the amount of shrinkage t is secured when a load is applied.

[0019] The shrinkage restricting member 17 may be made of not only round steel but also other metal materials in a cylindrical or hollow circular shape, or in a rectangular or other prismatic shape or hollow angular shape. The size is not particularly limited as long as the total cross-sectional area can support the required load, and the material may be synthetic resin or other composite materials. Furthermore, the number of embedded pieces may be appropriately determined according to the required load.

[0020] As a result, even if a load is applied to the rubber mat 15, it can only physically shrink up to the amount of shrinkage t, and the rubber mat 15 ensures a thickness of Tt when the amount of shrinkage t is reached. When the load applied to one steel shell support member 14 by the steel shell 12 is, for example, about 30 tons, the rubber mat 15 is shaped as a square area with a thickness of 30 mm and one side measuring 300 mm, and when the amount of shrinkage t of the rubber mat 15 is 5 mm, the shrinkage restricting member 17 is embedded with a height of 25 mm. By doing so, the thickness T of the rubber mat 15 portion itself and the thickness of the friction-increasing mat 20 other than this can be ensured to be as thick as 30 mm, while at the same time the amount of shrinkage t can be suppressed to 5 mm.

[0021] The bottom plate member 16 of the bottom slab structure 10 is a plate material such as metal or synthetic resin that is joined to the upper surface of the rubber mat 15. The area of ​​the bottom plate member 16 is approximately the same as the area of ​​the rubber mat 15, and for example, a square iron plate with a thickness of 16 mm and each side of 300 mm is used. The rubber mat 15 is integrated with the entire lower surface of the bottom plate member 16 by, for example, vulcanization adhesion. In this way, the load from the steel shell supporting member 14 can be uniformly distributed by the bottom plate member 16 and transmitted to the rubber mat 15 portion. The bottom plate member 16 is directly attached to the steel shell support member 14, which transmits the load of the steel shell 12, by welding or the like. The steel shell support member 14, the rubber mat 15, and the bottom plate member 16 may be attached and fixed before the concrete of the hybrid caisson 11 is poured, and may be appropriately determined depending on the manufacturing process. The above dimensions of the rubber mat 15 and the bottom plate member 16 are merely examples, and needless to say, they may need to be changed depending on various conditions such as the load of the steel shell 12. The shape and size of the rubber mat 15 and the bottom plate member 16 are rectangular (square) in the above description, but they may be other shapes such as rectangular, polygonal, or circular.

[0022] In addition, when the friction-increasing mats 20 are laid out side by side and in a front-rear and left-right arrangement, the steel shell support members 14 may be located not only inside the friction-increasing mats 20 but also at the joints, and in this case, as shown in Fig. 3 (only one side of the joint is shown), for example, the shrinkage-regulating members 17 are placed in three places, one at the center and two at the corners of the rubber mat 15, with the central one shifted inward so that they are not located on the joints. Similarly, shrinkage-regulating members (not shown) are placed in three places line-symmetrically in the rubber mat 15 on the opposite side of the corresponding joint, so that six shrinkage-regulating members 17 are used at the joints, instead of five shrinkage-regulating members 17 inside the friction-increasing mat 20, and the load of the steel shell 12 can be supported evenly. In such a joint portion of the rubber mat 15, a bottom plate member 16 is attached while covering it with a friction-increasing mat 20. Alternatively, a bottom plate member 16 corresponding to half of the rubber mat 15 can be used, and further attached to the steel shell support member 14 side so as to straddle the joint portion.

[0023] In the bottom plate structure 10, a friction-increasing mat 20 comprising a bottom plate member 16 and a rubber mat 15 portion is arranged in correspondence with the bottom surface 12a of the steel shell 12 of the hybrid caisson 11, but on the bottom surface of the hybrid caisson 11 other than the bottom plate member 16 and rubber mat 15 portion, the friction-increasing mat 20 is installed in an exposed state without the bottom plate member. Furthermore, in addition to the rubber mat 15 portion corresponding to the bottom surface 12a of the steel shell 12, the friction-increasing mat 20 is provided with anchor members 21 for bonding with the reinforced concrete 13. For example, the friction-increasing mat 20 is formed with a storage portion for storing the L-shaped anchor members 21, and during transportation, the anchor members 21 are stored in a flat shape, and after the hybrid caisson 11 is laid on the production yard base plate 1, the anchor members 21 are left protruding upward (see Figures 1 and 5).

[0024] In manufacturing the friction increasing mat 20 having such a rubber mat 15 portion, a mold with a height according to the thickness T of the rubber mat 15 portion and the like is prepared in advance during manufacturing, and the shrinkage regulating members 17 are evenly arranged in the mold in accordance with the rubber mat 15 portion, for example, five pieces, at four corners of a square and at the center, and then rubber raw material is filled and heated and vulcanized to embed the shrinkage regulating members 17. The shrinkage regulating members 17 are embedded at a height lower than the thickness T of the rubber mat 15 portion by the amount of shrinkage t, and the embedding position in the thickness T direction may be embedded flush with the front surface, flush with the back surface, or embedded in the middle, as long as the shrinkage t is secured somewhere in the thickness T. Furthermore, the bottom plate member 16 is integrated with the upper surface of the rubber mat 15 portion by vulcanization adhesion or the like. Furthermore, the friction-increasing mat 20 other than the rubber mat 15 portion has a receiving portion for receiving the L-shaped anchor member 21, and after molding, the anchor member 21 is received in an upright position. Furthermore, the friction-increasing mat 20 is provided with rubber mats 15 in accordance with the arrangement of the steel shell support members 14, and it goes without saying that the necessary number of mats to fit the joints are prepared in advance.

[0025] Next, the manufacturing process of the bottom slab structure 10 of the hybrid caisson will be described with reference to Figs. First, friction-increasing mats 20 each having a rubber mat 15 formed thereon in accordance with the arrangement of the steel shell support members 14 are laid out side by side in a front-to-back and left-to-right fashion on the manufacturing yard base plate 1 for the bottom slab structure 10 of the hybrid caisson. The anchor members 21 provided on the friction-increasing mat 20 do not necessarily have to be attached in advance and stored in a storage section for transportation, but may be installed in a later process, as long as it is before pouring of concrete after the steel shell support members 14 are installed.

[0026] Next, the steel shell 12 is hoisted by a crane or the like, and the steel shell support member 14 is placed on the bottom plate member 16 on the upper surface of the rubber mat 15. The steel shell support member 14 and the bottom plate member 16 of the steel shell 12 are connected by, for example, spot welding. As a result, the load of the steel shell 12 acts on each of the steel shell support members 14, but since the shrinkage control members 17 are embedded to suppress the amount of shrinkage t of the rubber mat 15, which is set to 5 mm or less, the steel shell 12 does not sink significantly, is not tilted, and can be installed in a predetermined state where the cover B is secured. Thereafter, the anchor members 21 housed in the friction-increasing mat 20 are protruded upward (see FIG. 5). The anchor members 21 may be erected after the reinforcing bars 13a described below are arranged, or before the concrete is poured.

[0027] After the steel shell 12 is thus installed, work such as placing reinforcing bars 13a in the space that will become the cover B of the reinforced concrete 13 is carried out, and concrete is poured to cover the steel shell 12 with the reinforced concrete 13 (see FIG. 4, etc.). In this way, the hybrid caisson 11 is completed, with a friction-increasing mat 20 having a rubber mat 15 portion attached to the bottom surface of the steel shell support member 14 via a bottom plate member 16, and the friction-increasing mat 20 being attached to the bottom surface of the hybrid caisson 11 via an anchor member 21.

[0028] This hybrid caisson 11 is placed on a rubble mound 3 formed of stones or the like. This results in a state in which the rubber mat 15 portion with a thickness T and the friction-increasing mat 20 are interposed between the hybrid caisson 11 and the rubble mound 3, allowing the hybrid caisson 11 to be installed in a stable state.

[0029] According to this bottom plate structure 10, a friction-increasing mat 20 having a rubber mat 15 portion is attached to the underside of the bottom plate member 16, and the load of the steel shell 12 is applied thereto, so that the rubber mat 15 portion can suppress the amount of shrinkage t between the rubble mound 3 and the frictional force can be applied. Furthermore, in this base slab structure 10, friction can be increased by the friction-increasing mat 20 which includes a rubber mat 15 portion, and the rubber mat 15 portion can be prevented from sinking significantly due to the load, thereby ensuring the covering thickness of the reinforced concrete 13 and eliminating the problem of insufficient cover B of the reinforced concrete 13. In addition, the rubber mat 15 portion can ensure thickness T even when the amount of shrinkage t is restricted, and the thickness T can be set and ensured regardless of the amount of shrinkage t of the rubber mat 15 portion, allowing for greater freedom in design, etc.

[0030] Therefore, according to the present invention, it is possible to provide a bottom slab structure 10 of a hybrid caisson 11 using a friction-enhancing mat 20 having a rubber mat 15 portion that is easy to install, inexpensive, and can satisfy the necessary friction-enhancing function. Furthermore, by using a steel shell support member made of a resin material or a steel shell support member made of a combination of steel and a resin material, the bottom surface 12a of the steel shell 12 and the bottom plate member 16 on the upper surface of the rubber mat 15 portion can be connected with a resin material without being connected with a metal material, and even if corrosion occurs in the metal material, the steel shell support member made of a resin material can block the spread of the corrosion and prevent rust.

[0031] Next, another embodiment of the present invention will be described, but duplicated explanations of the same parts as those already described will be omitted. In the above embodiment of the bottom plate structure 10, the friction-enhancing mat 20 is made of a rubber mat and the rubber mat 15 portion is molded integrally inside it, but this is not limited to the above, and the rubber mat 15 portion may be molded separately from the friction-enhancing mat 20. In this embodiment of the bottom plate structure 10, the rubber mat 15 portion which is molded separately has the same configuration as the rubber mat 15 portion already described, and is composed, for example, of a square rubber mat 15 with each side measuring 300 mm, a bottom plate member 16 attached to the upper surface of the rubber mat 15, and a shrinkage control member 17 embedded in the rubber mat 15, with the shrinkage control member 17 being embedded and having a height shorter than the thickness T of the rubber mat 15 by the amount of shrinkage t. The manufacturing method of this rubber mat 15 is also the same as that of the rubber mat 15 already described.

[0032] Next, the manufacturing process of the bottom slab structure 10 of the hybrid caisson will be explained with reference to Figs. First, a friction-increasing mat 20 is laid on the manufacturing yard base plate 1 of the hybrid caisson bottom slab structure 10, except for the location where the steel shell support member 14 is to be installed. In the friction-increasing mat 20, a through hole 20a corresponding to the size of the rubber mat 15 is formed in a portion corresponding to the bottom surface 12a of the steel shell 12. The friction-increasing mat 20 is also provided with an anchor member 21 for connecting with the reinforced concrete 13. For example, the friction-increasing mat 20 is formed with a storage portion for storing the L-shaped anchor member 21, and during transportation, the anchor member 21 is stored in a flat shape, and after the hybrid caisson 11 is laid on the production yard surface plate 1, it is left in a state of protruding upward (see Figs. 1 and 6).

[0033] When an asphalt mat is laid instead of a rubber mat as the friction-increasing mat 20, through holes corresponding to the size of the rubber mat 15 are formed in the asphalt mat using a formwork or the like. The asphalt mat is also provided with the necessary anchor members. In addition, the anchor members 21 provided on the friction-increasing mat 20 do not necessarily have to be attached in advance and stored in a storage section for transportation, but may be installed in a later process, as long as it is before pouring of concrete after the steel shell support members 14 are installed. Furthermore, when an asphalt mat is used as the friction-enhancing mat 20, the supporting load is smaller than when a rubber mat is used as the friction-enhancing mat 20, so supporting brackets are prepared not only for the steel shell supporting member 14 but also for other parts as necessary.

[0034] Next, the rubber mat 15 and the bottom plate member 16 are integrated into the through hole 20a of the friction-increasing mat 20, and the rubber mat 15 is attached onto the production yard base plate 1 of the hybrid caisson 11, thereby resulting in the rubber mat 15 and the friction-increasing mat 20 being laid over the entire surface.

[0035] Thereafter, the steel shell 12 is hoisted by a crane or the like, and the steel shell support member 14 is placed on the bottom plate member 16 on the upper surface of the rubber mat 15. The steel shell support member 14 of the steel shell 12 and the bottom plate member 16 are connected, for example, by spot welding. As a result, the load of the steel shell 12 acts on each of the steel shell support members 14, but since the shrinkage control members 17 are embedded in the rubber mat 15 to suppress the amount of shrinkage t of the rubber mat 15, which is set to 5 mm or less, the steel shell 12 does not sink significantly and can be installed in a predetermined state where the cover B is secured without tilting.

[0036] After the steel shell 12 is thus installed, work such as placing reinforcing bars 13a in the space that will become the cover B of the reinforced concrete 13 is carried out, and concrete is poured to cover the steel shell 12 with the reinforced concrete 13 (see FIG. 4, etc.). In this way, the hybrid caisson 11 is completed, with a rubber mat 15 attached to the bottom surface of the steel shell support member 14 via a bottom plate member 16, and a friction-increasing mat 20 attached to the bottom surface of the hybrid caisson 11 other than the steel shell support member 14 via an anchor member 21.

[0037] This hybrid caisson 11 is placed on a rubble mound 3 formed of stones or the like. This results in the rubber mat 15 and the friction-increasing mat 20 being interposed between the hybrid caisson 11 and the rubble mound 3, allowing the hybrid caisson 11 to be installed in a stable condition.

[0038] According to this bottom plate structure 10, a rubber mat 15 is attached to the underside of the bottom plate member 16, and the load of the steel shell 12 is applied thereto, so that the rubber mat 15 can generate a frictional force between the rubble mound 3. In addition, in this base slab structure 10, friction can be increased by the friction-increasing mat 20, and the rubber mat 15 can be prevented from sinking significantly due to the load, thereby ensuring the covering thickness of the reinforced concrete 13 and eliminating the problem of insufficient cover B of the reinforced concrete 13. In addition, the rubber mat 15 can have a thickness T even when the amount of shrinkage t is restricted, and the thickness T can be set independently of the amount of shrinkage t of the rubber mat 15 itself, allowing for greater freedom in design, etc.

[0039] Therefore, according to the present invention, it is possible to provide a bottom slab structure 10 of a hybrid caisson 11 that uses a separate rubber mat 15 that is easy to install, inexpensive, and can satisfy the necessary friction-increasing function. The same effect can be obtained when an asphalt mat is used as the friction-enhancing mat 20. Furthermore, by using a steel shell support member made of a resin material or a steel shell support member made of a combination of steel and resin material, the bottom surface 12a of the steel shell 12 and the bottom plate member 16 on the upper surface of the rubber mat 15 can be connected with a resin material rather than with a metal material, and even if corrosion occurs in the metal material, the steel shell support member made of resin can block the spread of corrosion and prevent rust.

[0040] In addition, in the bottom slab structure 10, a recess may be formed instead of a through hole 20a in the portion of the friction-increasing mat 20 where the steel shell support member 14 is located, and by positioning the friction-increasing mat 20 on the bottom surface of the rubber mat 15, adjustments and responses to unevenness in the rubble mound 3 can be made effective only in the amount of the friction-increasing mat 20 in the recess. In this case, in the bottom plate structure 10, the rubber mat 15 is integrated with the underside of the bottom plate member 16 by vulcanization bonding or the like and placed on the recess of the friction-increasing mat 20, and the sum of the shrinkage amount t of the rubber mat 15 due to the load of the steel shell 12 and the shrinkage amount of the recess of the friction-increasing mat 20 due to the load of the steel shell 12 is set so as to be within an allowable range, and the sum of the shrinkage amounts may be set to, for example, 5 mm or less of the allowable shrinkage amount t.

[0041] As described above in detail in conjunction with the embodiment, the hybrid caisson base structure 10 is a base structure 10 of a hybrid caisson 11 in which a hybrid caisson 11 composed of a steel shell 12 and reinforced concrete 13 covering the steel shell 12 is installed on a rubble mound 3, and is provided with a plurality of bottom plate members 16 that support the load of the steel shell 12 via a plurality of steel shell support members 14 that support the bottom surface 12a of the steel shell 12, and a rubber mat 15 provided on the underside of the bottom plate members 16 to increase friction with the rubble mound 3, suppress the amount of shrinkage t due to the load of the steel shell 12, and ensure a covering thickness B of the reinforced concrete 13 between the bottom surface 12a of the steel shell 12 and the bottom surface 12a of the steel shell 12. In the rubber mat 15 on the underside of the bottom plate member 16 below the steel shell support members 14, a shrinkage restriction member 17 that is lower than the thickness T of the rubber mat 15 by the amount of shrinkage t allowed for the supporting load applied to each steel shell support member 14 is embedded.

[0042] According to this configuration, the steel shell support member 14 is placed on the bottom plate member 16 in correspondence with the position of the bottom surface 12a of the steel shell 12 of the hybrid caisson 11, and the steel shell 12 is supported on the lower surface of the bottom plate member 16 via a rubber mat 15 in which a shrinkage restricting member 17 is embedded. By installing the hybrid caisson 11 equipped with the rubber mat 15 on the rubble mound 3, even when the rubber mat 15 is used, it is possible to suppress large sinking due to the load of the steel shell 12 applied via the steel shell support member 14 and ensure the covering thickness B of the steel shell 12 by the reinforced concrete 13. This makes it possible to provide a bottom slab structure 10 of a hybrid caisson using a rubber mat 15 that satisfies the required friction increasing function and ensures the covering thickness B of the concrete. In other words, the amount of shrinkage t of the rubber mat 15 due to the load of the steel shell 12 applied through the steel shell support members 14 is restricted by the shrinkage restriction members 17, and can be restricted to, for example, 5 mm or less, and the thickness T of the rubber mat 15 can be secured regardless of the amount of shrinkage t. Furthermore, the friction-increasing function between the hybrid caisson 11 and the rubble mound 3 is ensured, and distortion of the hybrid caisson 11 itself can be prevented. Moreover, the construction is easy since it is only necessary to set the steel shell support member 14 on the bottom plate member 16 to which the rubber mat 15 is attached, and the necessary increase in friction can be achieved by the rubber mat 15.

[0043] In the present invention, when a steel shell support member 14 made of synthetic resin mortar is used instead of the above configuration, the friction coefficient of the synthetic resin surface is small, and as with the conventional support fittings, there is a problem that the friction increase effect in this area cannot be expected. However, by directly supporting the load with the rubber mat 15, it is possible to increase friction. In addition, the use of rubber mats as friction-increasing mats 20 instead of conventional support metal fittings embedded in the asphalt mat or conventional synthetic resin mortar steel shell support members 14 has been partially adopted. However, this causes problems such as a large amount of shrinkage due to the load of the steel shell 12, making it impossible to ensure the necessary pouring height of the reinforced concrete 13 in the adjacent parts, resulting in a shortage of cover B of the reinforced concrete 13. However, with the steel shell support members 14, the shrinkage amount t of the rubber mat 15 is kept within the allowable range by the shrinkage control members 17, so that the shrinkage amount t can be suppressed and the shortage of cover B of the reinforced concrete 13 can be eliminated.

[0044] In the present invention, a plurality of shrinkage restricting members 17 are embedded in the rubber mat 15 so as to make the amount of shrinkage t uniform. According to this configuration, the hybrid caisson 11 can be kept stable by suppressing the inclination of the steel shell 12 with the use of multiple shrinkage control members 17.

[0045] In the present invention, a bottom plate member 16 and a rubber mat 15 are fixed together and attached to a steel shell support member 14. According to this configuration, the bottom plate member 16 is integrated with the rubber mat 15 and attached to the steel shell support member 14, so that the hybrid caisson 11 can be easily constructed without providing an anchor member in the rubber mat 15 portion, and manufacturing is also easy.

[0046] In the present invention, a rubber mat is provided as a friction-increasing mat 20 having a retractable and erectable anchor member 21 under the bottom surface 12a of the steel shell 12 except where the bottom plate member 16 is disposed. According to this configuration, the entire bottom surface 12a of the steel shell 12 can be made up of the rubber mat 15 and the friction-increasing mat 20 for the rubber mat, making it easier to ensure the supporting load of the reinforced concrete 13 compared to when the friction-increasing mat 20 is made of an asphalt mat as in the past.

[0047] Furthermore, each component of the bottom plate structure 10 is not limited to the description in the above embodiment, and the shape, material, etc. may be changed as long as it does not change the gist of the present application. [Explanation of symbols]

[0048] 1. Manufacturing yard surface plate 2 Ground 3. Sacrifice Mound 10 Bottom plate structure 11 Hybrid caisson 12 Steel shell 12a Bottom 13. Reinforced Concrete 13a Steel Bar 14 Steel shell support member 15 Rubber Mat 16 Bottom plate member 17 Shrinkage control member 20 Friction-increasing mat 20a through hole 21 Anchor member B Cover (concrete covering thickness) T Rubber mat thickness t Rubber mat shrinkage Tt Height of shrinkage control member

Claims

1. A hybrid caisson base structure in which a hybrid caisson consisting of a steel shell and reinforced concrete covering the steel shell is installed on a rubble mound, a plurality of bottom plate members that support the load of the steel shell via a plurality of steel shell support members that support the bottom surface of the steel shell; a rubber mat provided on the underside of the bottom plate member to increase friction with the riprap mound and suppress the amount of contraction of the steel shell due to the load, thereby ensuring a covering thickness of the reinforced concrete between the bottom surface of the steel shell and the rubber mat; a shrinkage control member is embedded in the rubber mat on the lower surface of the bottom plate member below the steel shell support member, the shrinkage control member being lower than the thickness of the rubber mat by an amount corresponding to an allowable shrinkage amount due to a supporting load applied to each of the steel shell support members; The bottom plate structure of a hybrid caisson is characterized by the following:

2. The shrinkage regulating member is configured to be embedded in a plurality of pieces in the rubber mat so as to make the amount of shrinkage uniform. The bottom plate structure of a hybrid caisson as described in claim 1.

3. The bottom plate member and the rubber mat are fixed together and attached to the steel shell support member. The bottom plate structure of a hybrid caisson as described in claim 1.

4. A rubber mat for increasing friction having a retractable and erectable anchor member is provided under the bottom surface of the steel shell other than where the bottom plate member is disposed. The bottom plate structure of a hybrid caisson as described in any one of claims 1 to 3.

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