JP2004137807A - Construction method for caisson embankment and caisson embankment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method for a caisson embankment and the caisson embankment enabling reduction in cost by dispensing with the construction of a large-scale caisson and rip-rap mound, reduction in water pollution during construction work, and the shortening of a construction term. <P>SOLUTION: An installation face 13 on a sea bottom 17 is leveled to install a caisson 1, and inside filling sand 9 is charged between an external wall 6 and an internal wall 4. Next, a hole 23 is formed in the lower part of a hole 11 formed in the bottom face 10 of the caisson 1 using a double casing 19. A steel frame basket 27 is provided inside the hole 23 and the caisson 1, concrete 29 is placed, and inside filling sand 33 is charged on it. Furthermore, lid concrete 35 is placed on the inside filling sand 9 and the inside filling sand 33, and upper concrete 37 is placed in the vicinity of the upper end of the caisson 1 to complete a breakwater 39. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of constructing a caisson embankment and a caisson embankment for reflecting the energy of waves to the offshore side to maintain calmness in a port, and to maintain a ship or a facility in a port while navigating or anchoring. The present invention relates to a caisson embankment construction method and a caisson embankment that is fixed to the seabed using a foundation without a rubble mound as a base.
[0002]
[Prior art]
Conventionally, breakwaters at large depths and in places with severe wave conditions are often constructed with a caisson-type structure that is easy to add functionality and economical to construct, and most of them are gravity-type structures that use 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 driving a pile into a hole provided in a caisson, fixing the caisson to the ground, and constructing a seawall structure (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-8-311841
[0005]
[Problems to be solved by the invention]
However, in a gravity type breakwater using a direct foundation, a large-scale caisson needs to be constructed in an upright embankment because the weight of the breakwater resists wave power. In addition, large-scale rubble mounds need to be constructed for hybrid embankments.
[0006]
The present invention has been made in view of such a problem, and aims at reducing the cost without requiring construction of a large-scale caisson and rubble mound, and reducing water pollution during construction. Another object of the present invention is to provide a caisson embankment construction method and a caisson embankment capable of shortening the construction period.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a step (a) of installing a caisson on the bottom of a water, a step (b) of excavating a shaft below the caisson, and installing concrete in the shaft. And (c) forming a foundation.
[0008]
In the step (a), the water bottom is leveled as necessary, and a caisson is installed. The caisson is formed, for example, partially or entirely by arranging a reinforcing bar in a steel shell. In this case, concrete is installed in the steel shell after the step (a).
[0009]
In step (b), a shaft is excavated by rotating excavating means provided on a pipe inserted into the caisson. The excavating means may be one capable of expanding the diameter. In the step (c), if necessary, a reinforcing material is embedded in the concrete. The reinforcing material is obtained by integrating a plurality of steel materials, and is, for example, a steel frame cage, a reinforcing bar cage, or the like. In the step (c), a cast-in-place pile or a deep foundation is formed as a foundation.
[0010]
After the step (c), if necessary, a filling material such as sand is placed above the foundation to secure the wave force stability of the caisson. After that, the caisson may be buried on its side to form a seawall.
[0011]
In the first invention, a caisson is installed on 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. Combining the caisson with the foundation improves stability against external forces. The first invention can be applied to both deep water areas and normal deep water areas.
[0012]
A second invention is a caisson embankment constructed using the caisson embankment construction method of the first invention.
[0013]
The caisson is fixed to the bottom with a foundation formed using concrete and reinforcement. The foundation is, for example, a cast-in-place pile or a deep foundation. The caisson is formed, for example, by installing reinforced concrete in a steel shell. Filling material such as sand is placed above the foundation. In some cases, the side of the caisson is buried.
[0014]
BEST MODE FOR CARRYING OUT 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 sea floor 17, and FIG. 2 is a plan view of the caisson 1. FIG. 1 is a sectional view taken along line BB of FIG.
[0015]
As shown in FIGS. 1 and 2, the caisson 1 has, for example, a rectangular parallelepiped shape with 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 It is composed of an outer wall 6b, a convex portion 8 provided along the lower end of the outer wall 6a, an inner wall 4 provided on the bottom surface 10, a partition 2, and the like.
[0016]
A hole 11 is provided in the bottom surface 10, and the inner wall 4 is arranged inside the outer wall 6 along the periphery of the hole 11. The partition 2 is a wall that partitions a space 7 between the outer wall 6 and the inner wall 4. The RC part 5 of the caisson 1 has a reinforced concrete structure, and the steel shell part 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 area. To manufacture.
[0018]
FIG. 3 is a perspective view of the vicinity of the joint between the steel shell 3 and the RC part 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, as shown in FIG. 3, steel plates 12 are installed on both side surfaces of the outer wall 6 of the RC portion 5. The outer wall 6 of the RC part 5 and the steel plate 12 are integrated using a dowel (not shown). The upper end of the reinforcing bar 14 of the outer wall 6 of the RC portion 5 is arranged between the two steel plates 12. In addition, the steel plate 12 is also joined to the RC part 5 on the inner wall 2 and the partition 4 in the same manner as the outer wall 6.
[0019]
As shown in FIG. 3, after the steel plate 12 is fixed to the RC portion 5, the caisson 1 being manufactured is temporarily placed on a temporary mound provided outside the breakwater construction sea area. Then, the steel plate 12 of the steel shell 3 shown in FIG. 3 is extended upward.
[0020]
In the breakwater construction sea area shown in FIG. 1, sand is laid 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 is moored on the leveled installation surface 13. During towing, a lid (not shown) for closing the hole 11 is provided at the lower end of the caisson 1 as necessary. The lid (not shown) may have a structure that can be easily removed, or a material that allows the wing bit 21 (FIG. 4) to penetrate (for example, a NOMST method in which a concrete wall provided in a shaft during cutting of a tunnel is cut by a shield machine). Used, cuttable concrete, etc.).
[0021]
Next, the caisson 1 is sunk on the installation surface 13 while performing position adjustment. In the case of a structure in which a lid (not shown) provided in the hole 11 can be removed, the lid (not shown) is removed before and after the caisson 1 is settled.
[0022]
After the caisson 1 is installed on the installation surface 13, concrete (not shown) is filled into the inner wall 16 (FIG. 3) of the outer wall 6 (the partition 2 and the inner wall 4) of the steel shell 3 of the caisson 1. Concrete poured into the wall 16 of the steel shell 3 is integrated with the outer wall 6 (the partition 2 and the inner wall 4) of the RC part 5 by the reinforcing bar 14.
[0023]
Next, as shown in FIG. 1, filling sand 9 is put into a space 7 between the outer wall 6 and the inner wall 4 of the caisson 1. By charging the filling sand 9, stability against wave force during construction is achieved. The filling amount of concrete (not shown) and the filling sand 9 filled in the wall 16 (FIG. 3) is supported on the bottom ground without causing the caisson 1 to slide or fall due to the wave force received during construction. Is calculated as follows.
[0024]
FIG. 4 is a diagram illustrating a step of excavating the hole 23 in the seabed 17. As shown in FIG. 1, after the caisson 1 is laid on the seabed 17, the seabed 17 is provided with waterproof protection 25 along the periphery of the hole 11. The water stop protection 25 is formed using, for example, a water glass-based chemical. Then, using the all-round rotary excavator (not shown) installed on the water and the double casing 19 inserted into the caisson 1, pre-excavation of the seabed 17 below the hole 11 is performed. The double casing 19 has a diameter of about 2000 mm, for example.
[0025]
Next, a wing bit 21 is provided at the tip of the double casing 19, and the wing bit 21 is rotated using an all-round rotary excavator (not shown), and a hole 23 a is excavated in the seabed 17 below the hole 11. Then, the wing bit 21 is expanded, and the same place is excavated again to increase the diameter of the hole 23a. The excavated soil is taken into the double casing 19 and sent to the outside of the caisson 1. When a lid (not shown) for closing the hole 11 is provided at the lower end of the caisson 1, the double casing 19 and the wing bit 21 are passed through the lid (not shown), and the holes 23, 23a are formed. Drilling.
[0026]
FIG. 5 is a diagram showing a process of erection of the steel cage 27. The steel cage 27 is a unit in which steel frames are arranged in a tubular shape and integrated, and are prefabricated on land, divided and transported by sea. As shown in FIG. 4, after the excavation of the hole 23 whose diameter has been expanded is completed, the steel cage 27 is suspended in the caisson 1 and the hole 23 using a crane (not shown) or the like.
[0027]
FIG. 6 is a view showing a step of placing concrete 29 in the hole 23. After the steel cage 27 is erected, concrete 29 is poured into the hole 23 and the caisson 1 to form a large-diameter cast-in-place foundation 31. When the concrete 29 is poured, the overflowed water is discharged after performing turbid water treatment and Ph treatment. The concrete 29 is filled in the hole 23 and the portion surrounded by the inner wall 4 of the caisson 1. It is desirable that the caisson 1 be 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 suitable so that the breakwater 39 does not slide and is supported by the bottom ground against 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 a full-rotation excavator (not shown), for example, a large-diameter cast-in-place foundation 31 having a diameter of about 10.0 m can be formed.
[0029]
FIG. 7: is a figure which shows the process of pouring in the filling sand 33 above the large diameter cast-in-place foundation 31. FIG. As shown in FIG. 7, the filling sand 33 is poured into 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 shows a sectional elevation view of the breakwater 39, and FIG. 9 shows a plan view of the breakwater 39. FIG. 8 is a sectional view taken along line EE 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 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. A lid concrete 35 is placed on the upper surface of the above. Then, the upper concrete 37 is installed on the upper surface of the lid concrete 35.
[0032]
The breakwater 39 is formed by arranging a plurality of caissons 1 as shown in FIGS. 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, and keeps the calm in the port.
[0033]
Next, a second embodiment will be described. FIG. 10 is a sectional elevation view of the revetment structure 45. In the second embodiment, the steps from installation of the caisson 1 to installation of the upper concrete 37 are performed in the same manner as in the first embodiment. After that, a reclamation 47 outside the outer wall 6 on the land side 41 of the caisson 1 is performed to complete the seawall structure 45. The seawall structure 45 is formed by arranging a plurality of caissons 1 like 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 installed inside the caisson 1. The use of the large-diameter cast-in-place foundation 31 can provide a more stable and rational structure than a gravity-type one even in a deep part or a place where the wave conditions are severe.
[0035]
In the first and second embodiments, the production of the caisson 1 and the work of leveling the seabed 17 can be performed at the same time, and there is little incidental work such as installation of a rubble mound, so that the construction period can be shortened. In addition, since the large-diameter cast-in-place foundation 31 is constructed inside the caisson 1, the work of rolling 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 does not have a rubble mound, it can be easily constructed even in an area where rubble material is difficult to obtain. In addition, since it is possible to reduce the lifting pressure acting on the bottom surface of the caisson with respect to wave force, it is possible to design 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 the buoyancy can be secured, it may be manufactured in a factory on the revetment or in a dry dock. Movement to the sea area outside the sea area where the breakwater is installed may be performed as needed.
[0038]
In the first and second embodiments, the caisson 1 is towed with the lid (not shown) closing the hole 11 at the lower end of the caisson 1, but the installation position of the lid (not shown) is limited to this. Absent. A lid (not shown) for closing the hole 11 may be provided at the upper end of the caisson 1 and the caisson 1 may be towed. In this case, the lid (not shown) is formed of, for example, a steel material, and is provided with a valve or the like so that the pressure in the caisson 1 can be controlled. When sufficient buoyancy can be secured 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 frame cage 27 is installed in the hole 23 and the caisson 1 as a reinforcing material of the large-diameter cast-in-place foundation 31, but another steel unit such as a steel cage may be used. In the first and second embodiments, the caisson 1 is filled with the filling sand 9 and the filling sand 33, but other filling materials such as crushed stones may be used instead. In addition, the filling material such as the filling sand 9 and the filling sand 33 is filled as necessary so that stability against waves can be ensured at the time of construction of the breakwater 39 or the seawall structure 45 or after completion. .
[0040]
The shape of the caisson need not be that shown in FIGS. In the caisson 1, as shown in FIG. 2, two holes 11 are provided on the bottom surface 10, but the number of holes is not limited to this. The partition 2 and the inner wall 4 are arranged as needed.
[0041]
Further, the structure and material of the caisson are not limited to those described above. The upper half of the caisson 1 has the steel shell 3 and the lower half has the RC portion 5. However, if the buoyancy can be secured during towing, the entire caisson may have an RC structure. If buoyancy cannot be ensured, the entire caisson may have a steel shell structure. In the caisson having a steel shell structure, a steel plate serving as a side surface of the outer wall 6, the inner wall 4, and the like is assembled, and a reinforcing steel bar is arranged between the pair of steel plates to complete a steel shell of the caisson. Fill concrete between steel plates.
[0042]
4 and 5, the holes 23 and 23a are excavated using the wing bits 21 whose diameter can be expanded. However, the holes are excavated using the wing bits that cannot be expanded, and the foundation corresponding to the large-diameter cast-in-place foundation 31 is formed. May be formed. The method of constructing the breakwater 39 and the seawall structure 45 described in the first and second embodiments can be applied to both a deep sea area and a shallow sea area.
[0043]
【The invention's effect】
As described above in detail, according to the present invention, it is not necessary to construct a large-scale caisson and a rubble mound, and cost reduction can be expected. In addition, a caisson embankment capable of reducing water pollution during construction and shortening the construction period can be provided. Construction method and caisson embankment can be provided.
[Brief description of the drawings]
FIG. 1 is a sectional elevation view of a caisson 1 installed on a seabed 17 FIG. 2 is a plan view of the caisson 1 FIG. 3 is a perspective view near a joint portion between a steel shell 3 and an RC section 5 FIG. FIG. 5 shows a step of excavating a hole 23 in FIG. 5 FIG. 5 shows a step of erection of a steel cage 27 FIG. 6 shows a step of placing concrete 29 in the hole 23 FIG. FIG. 8 is a view showing a process of putting the filling sand 33 above the batting foundation 31. FIG. 8 is a sectional elevation view of the breakwater 39. FIG. 9 is a plan view of the breakwater 39. FIG. FIG. 11 is an elevation view of a conventional breakwater 101.
1 ... Caisson 2 ... Partition wall 3 ... Steel shell part 4 ... Inner wall 5 ... RC part 6 ... Outer wall 7 ... Space 9, 33 ... Filling sand 10 ... ... Bottom 11, 23, 23a ... Hole 17 ... Sea bottom 19 ... Double casing 27 ... Steel cage 29 ... Concrete 31 ... Large diameter cast-in-place foundation 37 ... Upper concrete 39 ... Breakwater 45 ... Seawall structure

Claims (10)

(A) installing a caisson on the bottom of the water;
Excavating a shaft below the caisson (b);
(C) placing concrete in the shaft and forming a foundation;
A method for constructing a caisson embankment, comprising: 2. The method according to claim 1, wherein in the step (b), the shaft is excavated by rotating excavating means provided on a pipe inserted into the caisson. 3. The method according to claim 2, wherein the excavating means is expandable. The method according to claim 1, wherein the foundation is a cast-in-place pile or a deep foundation. The method of claim 1, wherein a reinforcing material is buried in the concrete. The caisson embankment construction method according to claim 5, wherein the reinforcing material is formed by integrating a plurality of steel materials. The method for constructing a caisson embankment according to claim 1, wherein the caisson has a reinforcing bar arranged in a steel shell, and concrete is installed in the steel shell after the step (a). . The method for constructing a caisson embankment according to claim 1, further comprising a step (d) of installing a filling material above the foundation. The method for constructing a caisson embankment according to claim 1, further comprising a step (e) of burying a side of the caisson. A caisson embankment constructed using the caisson embankment construction method according to any one of claims 1 to 9.

Images