Ground-embedded quay

Abstract

To provide an embedment type wharf wall which is economical while maintaining comparatively high earth quake performance.SOLUTION: An embedment type wharf wall has a first embedment structure 13 embedded in the foundation G1 of a seabed, a second embedment structure 14 embedded in the foundation G1 on a side closer to the land than the first embedment structure 13, a bottom slab 12 joined to the upper parts of the first embedment structure 13 and the second embedment structure 14, and an earth retaining 10 that has a side wall 11 extending upward from a sea side end of the bottom slab 12 and has an L shape in cross-sectional view.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an embedded quay wall provided at a coastal area which is the boundary between the sea and the land.

Background Art

[0002] In recent years, ships have been increasing in size, and there has been a growing need for ports to equip quay walls with large draft. Although the demand for quay walls with large draft is increasing, since quay walls have to be constructed on soft ground, the greater the draft is when designing a quay wall, the more insufficient the seismic resistance during an earthquake, and it is difficult to form a cross-section in the conventional form. Therefore, it has been considered to use a caisson with high rigidity as a foundation to make a quay wall applicable to soft ground and large earthquakes (for example, refer to Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even if a caisson foundation with embedment is applied to a quay wall according to the conventional concept, it does not become an advantageous structure just by that. Since the caisson foundation has high rigidity, bending deformation does not occur in the structure even during a large earthquake, but the deformation of the ground cannot be suppressed without devising the structural form, and large deformation occurs following the ground deformation. Among the various types of quays, gravity quays are a structural system that aims to withstand deformation during earthquakes by installing heavy wall bodies on the ground. However, ordinary gravity quays cannot avoid significant deformation during massive earthquakes. For example, during the 1995 Great Hanshin Earthquake, the caisson-type quays at Kobe Port displaced 4-5 meters towards the sea. This was because the soft ground beneath the wall body underwent lateral flow during the earthquake. In other words, while ordinary gravity quays can somewhat suppress the lateral displacement of the ground behind the wall body (the landward portion above the seabed), if the ground beneath the wall body flows, the wall body, which is merely resting on the flowing ground, will displace towards the sea along with the ground. Therefore, if a portion of the wall body is embedded in the ground, it can be expected to exert a certain degree of restraint against lateral flow beneath the wall body. However, embedding large caissons by excavating the original ground is costly, and there was room for improvement from an economic standpoint.

[0005] This invention has been made in view of the above-mentioned problems, and its purpose is to provide an economically efficient embedded quay wall while maintaining relatively high seismic resistance. [Means for solving the problem]

[0006] The embedded quay designed to achieve the above objective is an embedded quay constructed in the coastal area, which is the boundary between the sea and the land, and its characteristic structure is as follows: The first embedding structure is embedded in the seabed, A second embedding structure is embedded in the ground on the landward side of the first embedding structure, The structure comprises an L-shaped earth retaining wall that is L-shaped in a lateral cross-section, having a base plate joined to the upper part of the first embedded structure and the second embedded structure, and a side wall extending upward from the seaward end of the base plate. The first embedded structure and the second embedded structure are caisson foundations. The embedding depth of the first embedding structure and the second embedding structure is 4m or more and 10m or less. The ratio of the vertical length of the side wall of the L-shaped retaining wall to the vertical length of the first embedded structure, and the ratio of the vertical length of the side wall of the L-shaped retaining wall to the vertical length of the second embedded structure, are between 1.4 and 5.0.

[0007] According to the above-described characteristic configuration, as shown in Figure 1, the structure has a first embedding structure on the seaward side and a second embedding structure on the landward side of the first embedding structure. Therefore, by making the embedding depth shallower, it is possible to increase seismic resistance while keeping costs relatively low. Specifically, a structure was devised in which a first embedding structure and a second embedding structure (for example, about 6m wide and 4-7m high) with relatively narrow widths (width in the direction intersecting the coastline) are embedded in the ground below the seabed, as shown in Figure 1, and an L-shaped earth retaining wall (for example, made of reinforced concrete, with a vertical length L7 of about 16m to 20m) is joined on top of them. Since the ground sandwiched between the first embedding structure and the second embedding structure is constrained, a structure can be constructed in which a virtual wall K, enclosed by a dashed line, is embedded in the ground below the seabed. In other words, by integrating the L-shaped retaining wall with the first and second embedding structures, a wall with virtual embedding (the area enclosed by the dashed line in Figure 1) can be constructed at a relatively low cost. Furthermore, in the above-described configuration, if both the base slab and side walls of the L-shaped retaining wall are made to a thickness of approximately 1 m, it is possible to prevent the members from yielding (being damaged). This configuration effectively suppresses the movement of the embedded quay wall.

[0008] Furthermore, compared to conventional technology, the embedded quay wall of the present invention, having the above-described characteristic configuration, allows for the construction of an embedded gravity wall, which was impossible with conventional technology, at a relatively low cost, and enables the width of the wall to be increased to improve seismic performance. In other words, while conventional technology increases construction costs almost proportionally to the wall width (width in the direction intersecting the coastline), the embedded quay wall of the present invention, even if the wall width (width along arrow X in the area enclosed by the dashed line in Figure 1) increases, only the increase in the base slab width significantly affects the construction costs. Therefore, the increase in construction costs is less relative to the increase in wall width. That is, the present invention offers greater economic advantages when the water depth is deep (for example, 14.5m or more) and the seismic load is large, requiring a wider wall. Furthermore, the first and second embedded structures may be constructed using methods such as pneumatic caissons sunk by compressed air, open caissons that do not use compressed air, or caissons constructed on land that are transported to the sea and sunk by excavating the seabed. etc. Other structural forms that exhibit similar seismic behavior to caissons are also conceivable. There is no difference in seismic performance regardless of the method used, and the most appropriate one should be adopted depending on the site conditions. Based on the above characteristics and configuration, it is possible to realize an economically efficient embedded quay while maintaining relatively high seismic resistance. Furthermore, the embedded quay wall according to the present invention is a large-scale structure used in coastal areas with great water depth, and its dimensional relationship differs significantly from that of concrete blocks used for retaining walls on land. Here, the vertical length of the side wall of the L-shaped earth retaining structure according to the present invention is approximately 14m to 20m, and the vertical length of the first and second embedded structures is approximately 4m to 10m, making it suitable for large structures.

[0009] Further characteristic features of embedded quay walls include: The vertical length of the second embedding structure may be longer than the vertical length of the first embedding structure.

[0010] For the first and second embedded structures, a deeper embedment depth of approximately 4 to 7 meters is considered to result in higher seismic resistance, but a shallower embedment depth is more advantageous in terms of construction costs. Therefore, it is conceivable to vary the embedment depth of the first and second embedded structures. As described above, by making the vertical length of the second embedded structure longer than the vertical length of the first embedded structure, the virtual wall K (the wall enclosed by the dashed line in Figure 7) takes on an inverted trapezoidal shape with different embedded lengths, as shown in Figure 7. However, because the center of gravity is located on the landward side of the center of the virtual wall K, an excellent balance between cost and seismic performance can be obtained.

[0011] Further characteristic features of embedded quay walls include: The first and second embedded structures have an elongated shape that extends in a direction along the coastline of the coastal area. The first embedded structure and the second embedded structure may have an auxiliary caisson that extends in a direction intersecting both the elongated first embedded structure and the second embedded structure, and that connects to both the first embedded structure and the second embedded structure.

[0012] The first and second embedded structures are connected via an L-shaped retaining wall. However, if an auxiliary caisson is installed between the first and second embedded structures to maintain the distance between them, stability can be maintained even against large deformations during earthquakes. The auxiliary caisson can have a shallower embedment depth and a minimum width (length along the coastline) compared to the first and second embedded structures. [Brief explanation of the drawing]

[0015] [Figure 1] This is a lateral cross-sectional view of a quay wall embedded according to an embodiment. [Figure 2] This is a plan view of the embedded quay wall according to the embodiment. [Figure 3] This figure shows a model used when performing seismic response analysis on a conventional quay wall. [Figure 4] This figure shows the model used when performing seismic response analysis on a embedded quay wall according to the embodiment. [Figure 5] This graph shows the input ground motion used when performing seismic response analysis. [Figure 6]It is a graph showing the relationship between the embankment width as the earthquake response analysis result and the displacement amount of the quay wall toward the sea side. [Figure 7] It is a side sectional view of the embedded quay wall according to another embodiment. [Figure 8] It is a schematic view showing a first embedding structure, a second embedding structure, and an auxiliary caisson according to another embodiment. [Figure 9] It is a schematic view showing a first embedding structure, a second embedding structure, and an auxiliary caisson according to another embodiment.

Mode for Carrying Out the Invention

[0016] The embedded quay wall 100 according to the embodiment of the present invention relates to one with good economy while exhibiting relatively high earthquake resistance performance. Hereinafter, based on FIGS. 1 to 6, the embedded quay wall 100 according to the embodiment will be described.

[0017] As shown in the side sectional view of FIG. 1 and the plan view of FIG. 2, the embedded quay wall 100 according to the embodiment is provided on the quay wall that is the boundary between the sea and the land, and includes a first embedding structure 13 that is excavated and embedded in the original ground G1 (an example of the ground) on the seabed, a second embedding structure 14 that is excavated and embedded in the original ground G1 on the land side (the tip side of the arrow X in FIGS. 1 and 2) with respect to the first embedding structure 13, a bottom plate 12 joined to the upper portions of the first embedding structure 13 and the second embedding structure 14, and a side wall 11 extending upward in the vertical direction (the tip side of the arrow Z in FIGS. 1 and 2) from the sea side end of the bottom plate 12 (the end on the base end side of the arrow X in FIGS. 1 and 2). It includes an L-shaped earth retaining structure 10 in a side sectional view. Here, joining includes fixing and fixing using an anchor or the like, and fitting and adhering as described later. The first embedding structure 13, the second embedding structure 14, and the L-shaped earth retaining structure 10 can be preferably formed of reinforced concrete. In this embodiment, it is assumed that the first embedding structure 13 and the second embedding structure 14 are entirely embedded in the original ground G1. In this embodiment, a first embedding structure 13 is provided on the seaward side of the central position of the L-shaped retaining wall 10 in the direction perpendicular to the coastline of the L-shaped retaining wall 10, and a second embedding structure 14 is provided on the landward side of the central position of the L-shaped retaining wall 10. Furthermore, the planar shape of the first embedding structure 13 and the second embedding structure 14 is not limited to a rectangle; it may also be circular, oval, or other shapes.

[0018] Furthermore, the upper end surfaces of the first embedded structure 13 and the second embedded structure 14 and the lower end surface of the L-shaped retaining wall 10 have interlocking protrusions and recesses (not shown) that can fit together, and these protrusions and recesses are joined together using concrete, anchors, etc. Furthermore, the base plate 12 and side wall 11 of the L-shaped retaining wall 10 are an integrated structure. The base plate 12 and side wall 11 of the L-shaped retaining wall 10 have interlocking protrusions and indentations (not shown), and they may be bonded together by fitting these protrusions and indentations using concrete or the like. Also, the position where the base plate 12 and side wall 11 of the L-shaped retaining wall 10 are fitted together can be anywhere.

[0019] Now, the embedded quay wall 100 according to this embodiment is configured as a relatively large quay wall, and as shown in Figure 1, the vertical length L6 of the first embedded structure 13 and the second embedded structure 14 is approximately 4m to 10m. In addition, the length L8 in the direction intersecting the coastline (orthogonal direction: along arrow X in Figure 1) is approximately 6m. On the other hand, the length L7 of the L-shaped retaining wall 10 in the vertical direction is approximately 14m to 20m, and the length L3 in the direction intersecting the coastline (orthogonal direction: along arrow X in Figure 1) is approximately 15m to 22m. Furthermore, the thickness L10 of the base slab 12 and side walls 11 of the L-shaped retaining wall 10 is approximately 1m, which is more than twice the thickness of the base slab 12 and side walls 11 of a typical L-shaped retaining wall 10. Incidentally, the ratio of the vertical length L7 of the side wall 11 of the L-shaped retaining wall 10 to the vertical length L6 of the first embedded structure 13, and the ratio of the vertical length L7 of the side wall 11 of the L-shaped retaining wall 10 to the vertical length L6 of the second embedded structure 14, are between 1.4 and 5.0.

[0020] Above the L-shaped retaining wall 10, backfill stones U are placed in contact with the upper surface of the base slab 12 and the landward side of the side wall 11, and then the backfill soil S is placed on top of the backfill stones U. As a result, the area enclosed by the dashed line in Figure 1 functions as a virtual wall K, which reduces the amount of reinforcing steel and other materials required to construct structural members such as the virtual wall K. In addition, the use of backfill stones contributes to suppressing deformation of the quay wall during earthquakes, thus also having the effect of reducing the width of the virtual wall itself.

[0021] Furthermore, the vertical length L4 of the virtual wall K of the embedded quay wall 100 according to this embodiment is approximately 20m to 27m. Incidentally, the length of the virtual wall K in the direction along the coastline (the direction along arrow Y in Figures 1 and 2) is not particularly limited and can be, for example, 30m or less. Furthermore, the quay can be constructed by arranging multiple embedded quay walls 100 in a row along the coastline. Incidentally, buffer material made of rubber or the like is placed between multiple L-shaped earth retaining walls 10.

[0022] Next, the results of the seismic performance analysis of the embedded quay wall 100 (model shown in Figure 4) according to this embodiment are shown in comparison with the conventional technology (model shown in Figure 3). The ground conditions are as shown in Tables 1 and 2 below. The planned water depth was set to -14.5m. In the models shown in Figures 3 and 4, the direction along the coastline (direction along arrow Y) was assumed to be uniform, and the analysis was performed on a 1m width in that direction. The ground conditions were set to be intermediate, ranging from soft to good, for the quay construction site. The planned water depth was set to 14.5m, taking into account the increasing size of modern vessels. The dam body width L3 was set to 21.5m for both the conventional technology shown in Figure 3 and the embedded quay 100 of this embodiment shown in Figure 4. Incidentally, in the conventional technology model, the length L5 of the rubble mound 21 in the orthogonal direction perpendicular to the coastline was set to 40.5m, and the length L4 in the vertical direction was set to 22.5m. On the other hand, in the model of the embedded quay 100 according to this embodiment, the vertical length L4 of the virtual wall was set to 22.5m and 25.5m. L1: 100m, L2: 121.5m, L6: 4m~7m, L7: 18.5m, L8: 6m, T1: 11m, T2: 10.5m, T3: 18.5m, T4: 5m, T5: 14.1m, T6: 3.4m, T7: 14.5m, T8: 4.5m, T9: 10.6m.

[0023] [Table 1]

[0024] [Table 2]

[0025] In this analysis, the two-dimensional finite element method was used, and the finite element seismic response analysis code was FLIP. FLIP is currently the standard analysis code used in seismic response analysis of port structures.

[0026] The input ground motion was defined as the ground motion during a megathrust earthquake, as shown in Figure 5, and was the incident seismic wave on the engineering bedrock at Kobe Port during the 1995 Great Hanshin Earthquake. This seismic wave was input to the lower end of the model (the lower end of the original ground layer). The analysis results are shown in Figure 6. The horizontal axis represents the width of the dam body, and the vertical axis represents the displacement toward the sea. The solid line represents the case where the embedment depth is 4m in this embodiment, the dashed line represents the case where the embedment depth is 7m in this embodiment, and the dashed line represents the case of the conventional technology. Under the same dam width conditions, the deformation amount of this embodiment is significantly smaller compared to the conventional technology, indicating high seismic resistance. In particular, in the case of a foundation depth of 7m, the deformation amount of this embodiment is 70% less than that of the conventional technology, demonstrating high seismic resistance.

[0027] Furthermore, although the details will be omitted here, the inventors have confirmed through simulation analysis that this embodiment is economically superior to the conventional technology.

[0028] [Another embodiment] (1) In the above embodiment, the first embedded structure 13 and the second embedded structure 14 are assumed to be entirely embedded in the in-ground G1, but it is also acceptable for only a part of them to be embedded in the in-ground G1.

[0029] (2) In the above embodiment, the vertical lengths of the first embedding structure 13 and the second embedding structure 14 were approximately the same. However, for example, as shown in Figure 7, the vertical length L13 of the second embedding structure 14 may be made longer than the vertical length L12 of the first embedding structure 13. In this case, the virtual wall K is the area enclosed by the dashed line in Figure 7. As a result, the virtual wall K (the wall enclosed by the dashed line in Figure 7) has an inverted trapezoidal shape with different embedment lengths, but because the center of gravity is located on the landward side of the center of the virtual wall K, an excellent balance between cost and seismic performance can be obtained.

[0030] (3) As shown in the plan view of Figure 8, the first embedding structure 13 and the second embedding structure 14 have an elongated shape that extends in the direction along the coastline (arrow Y direction in Figure 8), and an auxiliary caisson 15 may be provided between the first embedding structure 13 and the second embedding structure 14, extending in a direction that intersects both the elongated first embedding structure 13 and the second embedding structure 14 (orthogonal direction in Figure 8) and joining to both the first embedding structure 13 and the second embedding structure 14. The thickness L9 of the auxiliary caisson 15 in the direction along the coastline (arrow Y direction in Figure 8) may be thinner than the thickness L8 of the first embedded structure 13 and the second embedded structure 14 in the direction intersecting the coastline (arrow X direction in Figure 8). The first embedding structure 13 and the second embedding structure 14 may be provided in multiple locations for a single virtual wall K, or in other words, for a single L-shaped retaining wall 10. Furthermore, the first embedded structure 13 and the second embedded structure 14 may be shorter than the length of one L-shaped retaining wall 10 in the direction along the coastline. For example, as shown in the plan view of Figure 9, the first embedding structure 13 may be provided separately for one virtual wall K, or in other words, for one L-shaped retaining wall 10, and the second embedding structure 14 may be shorter than the L-shaped retaining wall 10 in the direction along the coastline (arrow Y direction in Figure 9). Although not shown in the illustrations, in the alternative embodiment shown in Figures 8 and 9, L-shaped earth retaining walls 10 are provided in each region enclosed by the dashed lines representing the virtual wall K in Figure 8. Also, in the alternative embodiment shown in Figures 8 and 9, the vertical depths of the first embedded structure 13 and the second embedded structure 14 may be approximately the same.

[0031] (4) In the L-shaped retaining wall 10, the side wall 11 is not limited to being joined to the seaward end of the base slab 12, but may also be joined to the upper surface of the base slab 12 on the seaward side from the center in a direction perpendicular to the coastline. In addition, although not shown in the diagram, buttresses are installed to connect the side walls 11 and the base slab 12 in order to suppress bending deformation of the side walls 11 of the L-shaped retaining wall 10. The thickness of the buttresses is approximately 1 m in width per 10 m in the direction along the coastline (direction along arrow Y) as shown in Figure 2.

[0032] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, provided that no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention. [Industrial applicability]

[0033] The caisson-type quay of the present invention can be effectively used as an economically efficient embedded quay wall while maintaining relatively high seismic resistance. [Explanation of Symbols]

[0034] 10: L-shaped retaining wall 11: Side wall 12:Bottom plate 13: First embedment structure 14: Second embedment structure 15: Auxiliary caisson 100: Embedded quay wall G1: Original ground K: Virtual wall U:Urakomi stone

Claims

1. A quay built into the sea in a coastal area that marks the boundary between the sea and the land, The first embedding structure is embedded in the seabed, A second embedding structure is embedded in the ground on the landward side of the first embedding structure, The structure comprises an L-shaped earth retaining wall having a base plate joined to the upper part of the first embedded structure and the second embedded structure, and a side wall extending upward from the seaward end of the base plate, the L-shaped earth retaining wall having an L-shape in a lateral cross-section, The first embedded structure and the second embedded structure are caisson foundations. The embedding depth of the first embedding structure and the second embedding structure is 4 m or more and 10 m or less. A quay wall with embedded foundations, wherein the ratio of the vertical length of the side wall of the L-shaped retaining wall to the vertical length of the first embedded structure, and the ratio of the vertical length of the side wall of the L-shaped retaining wall to the vertical length of the second embedded structure, are between 1.4 and 5.

0.

2. The embedded quay wall according to claim 1, wherein the vertical length of the second embedded structure is longer than the vertical length of the first embedded structure.

3. The first and second embedded structures are elongated in shape and extend in a direction along the coastline of the coastal area. The embedded quay wall according to claim 1 or 2, wherein between the first embedded structure and the second embedded structure, there is an auxiliary caisson extending in a direction that intersects both the elongated first embedded structure and the second embedded structure, and joining to both the first embedded structure and the second embedded structure.

4. A quay built into the sea in a coastal area that marks the boundary between the sea and the land, The first embedding structure is embedded in the seabed, A second embedding structure is embedded in the ground on the landward side of the first embedding structure, The structure comprises an L-shaped earth retaining wall having a base plate joined to the upper part of the first embedded structure and the second embedded structure, and a side wall extending upward from the seaward end of the base plate, the L-shaped earth retaining wall having an L-shape in a lateral cross-section, A quay wall in which the vertical length of the second embedding structure is longer than the vertical length of the first embedding structure.

5. A quay built into the sea in a coastal area that marks the boundary between the sea and the land, The first embedding structure is embedded in the seabed, A second embedding structure is embedded in the ground on the landward side of the first embedding structure, The structure comprises an L-shaped earth retaining wall having a base plate joined to the upper part of the first embedded structure and the second embedded structure, and a side wall extending upward from the seaward end of the base plate, the L-shaped earth retaining wall having an L-shape in a lateral cross-section, The first and second embedded structures are elongated in shape and extend in a direction along the coastline of the coastal area. A quay wall with an auxiliary caisson between the first and second embedding structures, which extends in a direction that intersects both the elongated first and second embedding structures and connects to both the first and second embedding structures.

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