JP3999628B2 - Construction method of caisson dyke - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a caisson embankment construction method and caisson embankment for reflecting wave energy offshore to maintain calmness in the harbor, and for protecting ships or harbor facilities during navigation or anchoring. The present invention relates to a caisson dam construction method and a caisson dyke that are fixed to the sea floor using a foundation without a rubble mound.
[0002]
[Prior art]
Conventionally, breakwaters in deep areas and places with severe wave conditions are often constructed with a caisson-type structure that is easy to add functionality and economically, most of which are gravity-type using direct foundations Structure. FIG. 11 shows an elevation view of a conventional breakwater 101. As shown in FIG. 11, in order to construct the breakwater 101, a rubble mound 105 is formed on the seabed 103, and a caisson 107 is installed on the upper surface thereof.
[0003]
In addition, there is a method of building a revetment structure by driving a pile into a hole provided in the caisson and fixing the caisson to the ground (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
JP-A-8-311841
[0005]
[Problems to be solved by the invention]
However, a breakwater with a gravitational structure using a direct foundation resists wave power due to the weight of the breakwater, so it is necessary to construct a large caisson on an upright bank. In addition, it is necessary to construct a large-scale rubble mound on the hybrid bank.
[0006]
The present invention has been made in view of such problems. The object of the present invention is to eliminate the need for construction of large-scale caissons and rubble mounds, which can be expected to reduce costs, and to reduce water pollution during construction. The object of the present invention is to provide a caisson embankment and a caisson embankment construction method capable of shortening the construction period.
[0007]
[Means for Solving the Problems]
In order to achieve the above-described object, the first invention includes a step (a) of installing a caisson at the bottom of the water, a step (b) of excavating a shaft below the caisson, and the concrete in the shaft A caisson dam construction method comprising the step (c) of forming a foundation, wherein the caisson is provided with a hole in a bottom portion, and the step (b) includes two steps inside the caisson. A heavy casing is inserted to excavate below the hole, and then the double casing is provided with an excavating means capable of expanding the diameter, and the lower part of the hole is excavated while expanding the diameter to form a large diameter shaft. This is a method of constructing a caisson bank.
[0008]
In the step (a), the water bottom is leveled and a caisson is installed if necessary. The caisson is formed, for example, partly or entirely by arranging reinforcing bars in a steel shell. In this case, concrete is installed in the steel shell after the step (a).
[0009]
In the step (b), the shaft is excavated by rotating excavation means provided in the pipe inserted into the caisson. As the excavating means, one capable of expanding the diameter may be used. In the step (c), a reinforcing material is embedded in the concrete as necessary. The reinforcing material is obtained by integrating a plurality of steel materials, and is, for example, a steel frame or a reinforcing bar. In the step (c), a cast-in-place pile or a deep foundation is formed as a foundation.
[0010]
After step (c), if necessary, a filling material such as sand is installed above the foundation to ensure the wave power stability of the caisson. After that, the side of the caisson may be buried and a revetment structure may be used.
[0011]
In the first invention, a caisson is installed at the bottom of the water, a shaft is excavated below the caisson, and a reinforcing material and concrete are installed in the shaft to form a foundation. By combining the caisson and the foundation, stability against external force is improved. The first invention can be applied to both the deep water region and the normal water region.
[0013]
The caisson is secured to the bottom of the water using a foundation formed from concrete and reinforcement. The foundation is, for example, a cast-in-place pile or a deep foundation. The caisson is formed by installing reinforced concrete in a steel shell, for example. Above the foundation is a padding material such as sand. In some cases, the sides of the caisson are buried.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional elevation view of the caisson 1 installed on the seabed 17, and FIG. 2 is a plan view of the caisson 1. 1 is a cross-sectional view taken along line BB in FIG.
[0015]
As shown in FIGS. 1 and 2, the caisson 1 is, for example, a rectangular parallelepiped shape having an open top surface, a rectangular bottom surface 10, a long-side outer wall 6 a provided around the bottom surface 10, and a short-side direction. The outer wall 6b, the convex portion 8 provided along the lower end of the outer wall 6a, the inner wall 4 provided on the bottom surface 10, the partition wall 2 and the like.
[0016]
The bottom surface 10 is provided with a hole 11, and the inner wall 4 is disposed inside the outer wall 6 along the periphery of the hole 11. The partition wall 2 is a wall that partitions the space 7 between the outer wall 6 and the inner wall 4. The RC portion 5 of the caisson 1 has a reinforced concrete structure, and the steel shell portion 3 has a structure in which concrete is filled between steel plates 12 (FIG. 3).
[0017]
As shown in FIG. 1, in order to install the caisson 1 on the seabed 17, first, the entire RC part 5 and a part of the steel shell part 3 are placed in a floating dock (not shown) provided outside the breakwater construction sea area. To manufacture.
[0018]
FIG. 3 is a perspective view of the vicinity of the joint portion between the steel shell portion 3 and the RC portion 5. FIG. 3 is an enlarged perspective view of a portion shown in FIG. 1A, for example. In the floating dock, after the RC portion 5 is manufactured, the steel plates 12 are installed on both side surfaces of the outer wall 6 of the RC portion 5 as shown in FIG. The outer wall 6 of the RC part 5 and the steel plate 12 are integrated using a dowel (not shown). Between the two steel plates 12, the upper end portion of the reinforcing bar 14 of the outer wall 6 of the RC portion 5 is disposed. The inner wall 2 and the partition wall 4 are joined to the RC portion 5 in the same manner as the outer wall 6.
[0019]
As shown in FIG. 3, after fixing the steel plate 12 to the RC portion 5, the caisson 1 being produced is temporarily placed on a temporary mound provided outside the breakwater construction sea area. And the steel plate 12 of the steel shell part 3 shown in FIG. 3 is extended upwards.
[0020]
In the breakwater construction area shown in FIG. 1, sand is placed on the seabed 17 and the installation surface 13 is leveled. Then, the caisson 1 manufactured on the temporary mound is towed to the breakwater construction sea area shown in FIG. 1 and moored on the leveled installation surface 13. During towing, a lid (not shown) that closes the hole 11 is installed at the lower end of the caisson 1 as necessary. The lid (not shown) has a structure that can be easily removed, or is made of a material that can penetrate the wing bit 21 (FIG. 4) (for example, a NOMST method in which a concrete wall provided in a shaft is cut by a shield machine during tunnel excavation) Used concrete that can be cut).
[0021]
Next, the caisson 1 is sunk on the installation surface 13 while adjusting the position. In the case where the lid (not shown) installed in the hole 11 is removable, the lid (not shown) is removed before and after the caisson 1 is set.
[0022]
After the caisson 1 is installed on the installation surface 13, concrete (not shown) is filled in the wall 16 (FIG. 3) of the outer wall 6 (partition wall 2, inner wall 4) of the steel shell 3 of the caisson 1. The concrete cast in the inner wall 16 of the steel shell 3 is integrated with the outer wall 6 (partition wall 2, inner wall 4) of the RC portion 5 by the reinforcing bars 14.
[0023]
Next, as shown in FIG. 1, the filled sand 9 is introduced into the space 7 between the outer wall 6 and the inner wall 4 of the caisson 1. Stabilization against wave power during construction is achieved by introducing the filled sand 9. The filling amount of concrete (not shown) and filling sand 9 filled in the wall 16 (FIG. 3) is supported by the bottom ground without causing the caisson 1 to slide or toppling against the wave force received during construction. Calculated as follows.
[0024]
FIG. 4 is a diagram illustrating a process of excavating the hole 23 in the seabed 17. As shown in FIG. 1, after the caisson 1 is laid on the seabed 17, a waterstop protection 25 is applied to the seabed 17 along the periphery of the hole 11. The water stop protection 25 is formed using, for example, a water glass chemical. Then, using the all-round rotary excavator (not shown) installed on the water and the double casing 19 inserted into the caisson 1, the preceding excavation of the seabed 17 below the hole 11 is performed. The double casing 19 is, for example, one having a diameter of about 2000 mm.
[0025]
Next, a wing bit 21 is provided at the tip of the double casing 19, and these are rotated using an all-around rotary excavator (not shown) to excavate a hole 23 a in the seabed 17 below the hole 11. And the wing bit 21 is expanded and the same place is excavated again, and the diameter of the hole 23a is expanded. The excavated soil is taken into the double casing 19 and sent to the outside of the caisson 1. When a lid (not shown) that closes the hole 11 is installed at the lower end portion of the caisson 1, the double casing 19 and the wing bit 21 are passed through the lid (not shown) so that the hole 23 and the hole 23a. Drilling.
[0026]
FIG. 5 is a diagram showing a process of installing the steel frame 27. The steel frame 27 is an integrated steel frame arranged in a cylindrical shape, prefabricated on land, divided and transported by sea. As shown in FIG. 4, after excavation of the hole 23 whose diameter has been expanded, the steel rod 27 is suspended in the caisson 1 and the hole 23 using a crane (not shown) or the like.
[0027]
FIG. 6 is a diagram showing a process of placing concrete 29 in the hole 23. After the steel frame 27 is installed, the concrete 29 is placed in the hole 23 and the caisson 1 to form a large-diameter spot casting foundation 31. When placing the concrete 29, the overflowed water is discharged after being subjected to muddy water treatment or Ph treatment. The concrete 29 is filled in the hole 23 and the portion surrounded by the inner wall 4 of the caisson 1. The caisson 1 is preferably filled with a minimum amount of concrete 29.
[0028]
The large-diameter cast-in-place foundation 31 is a cast-in-place pile or a deep foundation, and is appropriate so that the breakwater 39 does not slide and is supported by the bottom ground against the wave force received when the breakwater 39 (FIG. 8) is completed. It is designed using a simple design method. By using the double casing 19, the wing bit 21, and the all-around rotary excavator (not shown), for example, a large-diameter spot-foundation foundation 31 having a diameter of about 10.0 m can be formed.
[0029]
FIG. 7 is a diagram showing a step of putting the filled sand 33 above the large-diameter spot casting foundation 31. As shown in FIG. 7, the filling sand 33 is put on the concrete 29 filled in the portion surrounded by the inner wall 4 of the caisson 1. Then, the upper surface of the filling sand 33 is leveled.
[0030]
FIG. 8 is a sectional elevation view of the breakwater 39, and FIG. 9 is a plan view of the breakwater 39. 8 is a cross-sectional view taken along line E-E in FIG. The upper half of FIG. 9 is a cross-sectional view taken along the line CC of FIG. 8, and the lower half is a plan view seen from the direction indicated by the arrow D in FIG.
[0031]
After leveling the upper surface of the filling sand 33 filled in the inner wall 4, as shown in FIG. 8, the filling sand 33 and the filling sand 9 filled between the outer wall 6 and the inner wall 4 of the caisson 1. The lid concrete 35 is installed on the upper surface. Then, the upper concrete 37 is installed on the upper surface of the lid concrete 35.
[0032]
As shown in FIGS. 2 and 9, the breakwater 39 is formed by arranging a plurality of caissons 1 side by side. The breakwater 39 reflects the energy of the waves to the offshore side by the side surface 6 of the sea side 43 and the upper concrete 37 to maintain the calmness in the harbor.
[0033]
Next, a second embodiment will be described. FIG. 10 is a sectional elevation view of the revetment structure 45. In the second embodiment, similarly to the first embodiment, the installation from the caisson 1 to the installation of the upper concrete 37 is performed. Thereafter, landfill 47 outside the outer wall 6 on the land side 41 of the caisson 1 is performed to complete the revetment structure 45. The revetment structure 45 is formed by arranging a plurality of caissons 1 in the same manner as the breakwater 39.
[0034]
As described above, in the first and second embodiments, the caisson 1 is installed on the seabed 17, and the large-diameter cast-in-place foundation 31 is constructed inside the caisson 1. By using the large-diameter cast-in-place foundation 31, it is possible to provide a rational structure that is more stable than the gravity type, even in places with a deep depth and severe wave conditions.
[0035]
In the first and second embodiments, the caisson 1 can be manufactured and the seabed 17 can be leveled at the same time, and there is little incidental work such as installation of a rubble mound, so the work period can be shortened. In addition, since the large-diameter cast-in-place foundation 31 is constructed inside the caisson 1, the construction for winding up the earth and sand on the seabed 17 is reduced, and water pollution in the construction sea area can be reduced.
[0036]
Since the breakwater 39 has a structure in which no rubble mound is installed, it can be easily constructed even in areas where it is difficult to obtain rubble material. In addition, since the lifting pressure acting on the bottom of the caisson with respect to the wave force can be reduced, it can be designed with an economical structure.
[0037]
In the first and second embodiments, the caisson 1 is manufactured in a sea area outside the sea area where the floating dock and the breakwater are installed, but the manufacturing place is not limited to this. If buoyancy can be ensured, it may be manufactured at a factory on the revetment or at a dry dock. Movement to the sea area outside the breakwater installed sea area may be performed as necessary.
[0038]
In the first and second embodiments, a lid (not shown) that closes the hole 11 is provided at the lower end of the caisson 1 and the caisson 1 is towed. However, the installation position of the lid (not shown) is not limited to this. Absent. The caisson 1 may be towed by installing a lid (not shown) that closes the hole 11 at the upper end of the caisson 1. In this case, the lid (not shown) is formed of, for example, a steel material, and a valve or the like is provided so that the pressure in the caisson 1 can be controlled. If sufficient buoyancy can be ensured without closing the hole 11 of the caisson 1, the caisson 1 may be towed without installing a lid.
[0039]
In FIG. 5, the steel rod 27 is installed in the hole 23 and the caisson 1 as a reinforcing material for the large-diameter cast-in-place foundation 31, but other steel material units such as a reinforcing rod may be used. In the first and second embodiments, the filling sand 9 and filling sand 33 are filled in the caisson 1, but other filling materials such as crushed stone may be used instead. Further, the filling materials such as the filling sand 9 and the filling sand 33 are filled as necessary so that the stability against waves can be secured at the time of construction of the breakwater 39 and the revetment structure 45 or after completion. .
[0040]
The shape of the caisson need not be the one shown in FIGS. In the caisson 1, as shown in FIG. 2, the holes 11 are provided in two places on the bottom surface 10, but the number of holes is not limited thereto. The partition wall 2 and the inner wall 4 are arranged as necessary.
[0041]
Furthermore, the structure and material of the caisson are not limited to those described above. In the caisson 1, the upper half portion is the steel shell portion 3 and the lower half portion is the RC portion 5. However, when buoyancy can be ensured during towing, the entire caisson may have an RC structure. Further, when buoyancy cannot be ensured, the entire caisson may have a steel shell structure. In the caisson of the steel shell structure, after assembling the steel plates that are the side surfaces of the outer wall 6, the inner wall 4, etc., placing the reinforcing bars between the paired steel plates to complete the caisson steel shell, this is installed on the seabed 17, Fill concrete between steel plates.
[0042]
4 and 5, the hole 23 and the hole 23 a are excavated using the wing bit 21 that can be expanded, but the hole is excavated using the wing bit that cannot be expanded, and the foundation corresponding to the large-diameter spot-foundation foundation 31 is obtained. May be formed. The construction method of the breakwater 39 and the revetment structure 45 described in the first and second embodiments can be applied to both deep water areas and shallow water areas.
[0043]
【The invention's effect】
As described above in detail, according to the present invention, it is not necessary to construct large-scale caissons and rubble mounds, and cost reduction can be expected. In addition, caisson dykes that can reduce water pollution during construction and shorten the construction period. Can provide construction method and caisson dyke.
[Brief description of the drawings]
1 is a sectional elevation view of a caisson 1 installed on the seabed 17. FIG. 2 is a plan view of the caisson 1. FIG. 3 is a perspective view of the vicinity of a joint between a steel shell portion 3 and an RC portion 5. FIG. FIG. 5 is a diagram showing a process of excavating a hole 23 in FIG. 5. FIG. 5 is a diagram showing a process of building a steel skeleton 27. FIG. 6 is a diagram showing a process of placing concrete 29 in the hole 23. Fig. 8 shows a process of putting the filling sand 33 above the foundation 31. Fig. 8 is a sectional elevation view of the breakwater 39. Fig. 9 is a plan view of the breakwater 39. Fig. 10 is a sectional elevation view of the breakwater structure 45. [Fig. 11] Elevated view of conventional breakwater 101 [Explanation of symbols]
1 ......... Caisson 2 ......... Partition wall 3 ...... Steel shell 4 ......... Inner wall 5 ......... RC part 6 ......... Outer wall 7 ......... Spaces 9, 33 ......... Inner sand 10 ... ... bottom surface 11, 23, 23a ......... hole 17 ......... sea floor 19 ... double casing 27 ... …… steel frame 29 ......... concrete 31 ......... large-diameter cast-in-place foundation 37 ......... upper concrete 39 ……… Breakwater 45 ……… Revetment structure

Claims (2)

A step (a) of installing a caisson on the bottom of the water;
Drilling a shaft below the caisson (b);
(C) forming the foundation by installing the vertical shaft concrete;
A caisson dyke construction method characterized by comprising:
The caisson is provided with a hole at the bottom, and the step (b) is a drilling means capable of inserting a double casing into the caisson to excavate the lower part of the hole and then expanding the diameter of the double casing. And constructing a caisson dyke by excavating the lower part of the hole while expanding the diameter to form a large diameter shaft . The caisson comprises an inner wall disposed along the perimeter of the hole;
2. The caisson dam construction method according to claim 1, wherein the step (c) forms a large-diameter foundation by placing concrete in the shaft and in the interior surrounded by the inner wall .

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