JP7516197B2 - Quay structure and method for constructing the quay structure - Google Patents

Description

The present invention relates to a quay structure and a method for constructing a quay structure.

In a quay wall structure, a steel retaining wall is cast deeper than the seabed to resist the back earth pressure. Steel sheet piles and steel pipe sheet piles are generally used as the steel material for the retaining wall, as they are easy to cast into the ground. When the water depth is large, the steel sheet piles and steel pipe sheet piles alone are insufficient to resist the back earth pressure, so a tie rod structure installed at the back and a pier structure installed at the front are used to support the horizontal force of the wall head and resist the back earth pressure. When adding a pier in front of the revetment normal line, a method of making the front pier a jacket structure is adopted as an economical and rapid construction method, but the retaining wall is not directly connected by the jacket, and the back earth pressure acting on the retaining wall is only transmitted to the jacket structure built on the sea side. As a result, steel material is required for both the retaining wall and the pier, and the amount of steel increases, which tends to reduce economic efficiency.

In response to this, Patent Document 1 proposes a technology for constructing an arch-shaped earth retaining wall that convexly faces the seaward side using sheet-like members, such as straight steel sheet piles. In this case, the backside earth pressure is transmitted to the legs of the jacket structure as horizontal tension in the earth retaining wall. By using tension rather than the bending rigidity of the earth retaining wall, it is possible to construct a steel sheet pile wall that can resist backside earth pressure while suppressing the increase in the amount of steel material that would result from an increase in the cross section or the addition of wale construction.

JP 2005-194867 A

However, in the case of a steel sheet pile wall as described in Patent Document 1, the backside earth pressure transmitted by tension from the retaining wall is resisted only by the support structure including the jacket structure, and the load borne by the support structure becomes excessive. As a result, the amount of steel material in the support structure increases, which is not only uneconomical but also makes construction more difficult.

The present invention aims to provide a quay structure and a method for constructing a quay structure that can reduce the load borne by the supporting structure while suppressing an increase in the amount of steel material.

[1] A quay structure comprising a retaining wall having bending resistance against back soil pressure, and a steel pipe sheet pile row including at least one steel pipe sheet pile arranged in a direction intersecting the wall surface direction from both ends of at least a portion of the wall surface direction of the retaining wall, wherein a first steel pipe sheet pile located at the end of the steel pipe sheet pile row opposite the retaining wall functions as at least a part of a support pile structure.
[2] The steel pipe sheet pile row includes a second steel pipe sheet pile connected to the retaining wall, and at least one third steel pipe sheet pile adjacent to the second steel pipe sheet pile in a direction intersecting the wall surface direction and connected to the second steel pipe sheet pile by fitting it with a joint.
[3] A wharf structure according to [1] or [2], in which the steel pipe sheet pile rows are arranged on the sea side of the ground, sandwiching a retaining wall therebetween.
[4] A quay structure described in any one of [1] to [3], further comprising a retaining pile structure located on the sea side of the support pile structure, and a connecting member connecting the support pile structure to the retaining pile structure.
[5] The quay structure described in [4], wherein the support pile structure includes a first steel pipe sheet pile and a first jacket leg that fits onto the outside of the head of the first steel pipe sheet pile, the bracing pile structure includes a bracing pile and a second jacket leg that fits onto the outside of the head of the bracing pile, and the connecting member includes a first connecting member that is arranged between the first jacket leg and the second jacket leg.
[6] A quay wall structure as described in [5], in which no joint is formed between the head of the first steel pipe sheet pile and an adjacent steel pipe sheet pile or an earth retaining wall, and the first jacket leg is fitted from the outside into the part where no joint is formed.
[7] The quay wall structure according to [5] or [6], wherein the connecting member includes a second connecting member connecting the first jacket leg to the retaining wall.
[8] The quay structure described in [7], wherein the retaining wall is composed of a plurality of steel pipe sheet piles connected to each other, the quay structure includes a fitting member that fits into the inside of the head of one of the plurality of steel pipe sheet piles, and the second connecting member is arranged between the first jacket leg and the fitting member.
[9] The steel pipe sheet pile row includes at least one fourth steel pipe sheet pile arranged between the retaining wall and the first steel pipe sheet pile, and the head of the fourth steel pipe sheet pile is separated from the second connecting member. A wharf structure as described in [7] or [8].
[10] A quay wall structure described in any one of [1] to [9], in which a stopper protrudes from the peripheral surface of the steel pipe sheet pile in a joint space enclosed by fitting the joints between the steel pipe sheet piles included in the steel pipe sheet pile row, and the joint space is filled with a filler material.
[11] A quay wall structure described in any one of [1] to [10], wherein the retaining wall is composed of a plurality of steel pipe sheet piles connected to each other, and the ends of the steel pipe sheet pile row on the retaining wall side are connected to the steel pipe sheet piles located at both ends of the section.
[12] The wharf structure according to [11], wherein the heads of the steel pipe sheet piles constituting the steel pipe sheet pile row and the steel pipe sheet piles constituting the earth retaining wall are fixed by copings.
[13] The quay wall structure according to any one of [1] to [12], wherein the embedment depth of the steel pipe sheet piles constituting the steel pipe sheet pile row is shallower than the embedment depth of the retaining wall.
[14] A method for constructing a wharf structure, comprising the steps of: constructing a retaining wall having bending resistance against back earth pressure; constructing a steel pipe sheet pile row by arranging at least one steel pipe sheet pile in a direction intersecting the wall surface direction from both ends of at least a portion of the wall surface direction of the retaining wall; and incorporating a first steel pipe sheet pile located at the end of the steel pipe sheet pile row opposite the retaining wall into a support pile structure.
[15] A method for constructing a wharf structure as described in [14], wherein the step of incorporating the first steel pipe sheet pile into the support pile structure includes a step of fitting a first jacket leg to the outside of the head of the first steel pipe sheet pile, and further includes a step of driving a backing pile on the sea side of the first steel pipe sheet pile using as a guide a second jacket leg connected to the first jacket leg via a connecting member.
[16] The method for constructing a wharf structure according to [14], further comprising the steps of: installing a first jacket leg, a second jacket leg located seaward of the first jacket leg, and connecting members connecting the first jacket leg to the second jacket leg; and driving backing piles using the second jacket leg as a guide, wherein the step of incorporating the first steel pipe sheet pile into the support pile structure includes the step of driving the first steel pipe sheet pile using the first jacket leg as a guide.

According to the above configuration, the retaining wall, which has bending resistance against back earth pressure, and the steel pipe sheet pile row behave as a U-shaped wall integrally against the ground, making it easy to build a quay wall structure with the desired bending rigidity against back earth pressure. In addition, the vertical ground reaction force received by the steel pipe sheet pile row can resist the rotational moment generated in the retaining wall by the back earth pressure. Therefore, it is possible to reduce the load borne by the support structure while suppressing an increase in the amount of steel material.

FIG. 1 is a plan view of a quay wall structure according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 2 is a cross-sectional view taken along line III-III in FIG. 2A-2C are diagrams showing examples of joints that can be used in the quay wall structure shown in FIG. 1; FIG. 2 is a diagram for explaining the embedded depth of the earth retaining wall in the quay wall structure shown in FIG. 1 . 1 is a graph showing the results of calculating the displacement relative to the total load by the finite element method (FEM) between an example of the first embodiment of the present invention and a comparative example that does not include a steel pipe sheet pile row. 13 is a graph showing the results of calculating, by FEM, the load sharing rate of a wall when the number of steel pipe sheet piles constituting a steel pipe sheet pile row is changed for an example of the first embodiment of the present invention. FIG. 4 is a cross-sectional view of a quay wall structure according to a second embodiment of the present invention. FIG. 11 is a diagram showing a comparison of displacements calculated by frame analysis for the wharf structures according to the embodiments of the present invention. FIG. 11 is a diagram showing a comparison of displacements calculated by frame analysis for the wharf structures according to the embodiments of the present invention.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Note that in this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals to avoid redundant description.

Figure 1 is a plan view of a quay wall structure according to a first embodiment of the present invention, and Figures 2 and 3 are cross-sectional views taken along lines II-II and III-III in Figure 1, respectively. As shown in the figures, the quay wall structure 1 includes an earth retaining wall 2 composed of a plurality of steel pipe sheet piles 21 connected to each other, a steel pipe sheet pile row 3 including at least one steel pipe sheet pile connected to each other for a predetermined number of steel pipe sheet piles 21 and arranged in a direction intersecting the wall surface direction of the earth retaining wall 2, and a support pile structure 4 including a steel pipe sheet pile 31 (first steel pipe sheet pile) located at the end of the steel pipe sheet pile row 3 opposite the earth retaining wall 2 and a jacket leg 42 fitted to the outside of the head of the steel pipe sheet pile 31. The steel pipe sheet pile row 3 is arranged on the sea side of the ground G with the earth retaining wall 2 in between.

In this embodiment, the steel pipe sheet pile 31 located at the end of the steel pipe sheet pile row 3 opposite to the earth retaining wall 2 functions as a part of the support pile structure 4 together with the jacket leg 42. In the illustrated example, in addition to the above-mentioned steel pipe sheet pile 31, the steel pipe sheet pile row 3 includes a steel pipe sheet pile 32 (second steel pipe sheet pile) connected to the earth retaining wall 2, and a steel pipe sheet pile 33 (third steel pipe sheet pile) adjacent to the steel pipe sheet pile 32 in a direction intersecting the wall surface direction of the earth retaining wall 2 and connected to the steel pipe sheet pile 32 by fitting with a joint, and is composed of three steel pipe sheet piles per location. In other examples, the number of steel pipe sheet piles constituting the steel pipe sheet pile row may be smaller. For example, the steel pipe sheet pile row is constituted by directly connecting the steel pipe sheet pile 32 connected to the earth retaining wall 2 and the steel pipe sheet pile 31 functioning as a part of the support pile structure, and an intermediate steel pipe sheet pile (third steel pipe sheet pile) may not be included. Alternatively, the steel pipe sheet pile connected to the retaining wall 2 may function as part of the support pile structure (i.e., the steel pipe sheet pile 32 and the steel pipe sheet pile 31 in the above example are the same), and the steel pipe sheet pile row may be composed of only one steel pipe sheet pile (first steel pipe sheet pile). Conversely, the steel pipe sheet pile row may include a greater number of steel pipe sheet piles, in which case two or more intermediate steel pipe sheet piles (third steel pipe sheet piles) are included.

In the illustrated example, the quay wall structure 1 further includes a support pile structure 5 located on the seaward side of the support pile structure 4, and a beam 6 which is a connecting member connecting the support pile structure 4 to the support pile structure 5. The support pile structure 5 includes a support pile 51 and a jacket leg 52 which fits onto the outside of the head of the support pile 51, and the beam 6 is disposed between the jacket legs 42, 52.

In this embodiment, the steel pipe sheet piles 21 are connected to each other, so that the retaining wall 2 has bending resistance against the back earth pressure from the ground G. In addition, in this embodiment, the steel pipe sheet pile row 3 is connected to both ends of the section S1 in the wall surface direction of the retaining wall, so that the steel pipe sheet piles 21 in section S1 and the steel pipe sheet pile rows 3 on both sides behave integrally as a U-shaped wall body W (shown surrounded by a chain line) against the ground G. The second moment of area of the wall body W is larger than that of a wall composed only of the steel pipe sheet piles 21 in section S1, for example, and the number of steel pipe sheet piles constituting the steel pipe sheet pile row 3 can be easily increased by increasing the number of the first steel pipe sheet piles 31 as required, and the second steel pipe sheet piles 32 and one or more third steel pipe sheet piles 33 as necessary. Therefore, in this embodiment, the bending rigidity of the quay structure 1 against the back earth pressure can be effectively improved.

The retaining wall 2 is embedded deeply to ensure passive earth pressure from the seabed, thereby obtaining resistance to the rear earth pressure of the quay wall structure 1, but the steel pipe sheet pile row 3 is not subjected to passive earth pressure in the direction that resists the rear earth pressure of the quay wall structure 1, and resists the rear earth pressure mainly by the vertical ground reaction force. Therefore, the embedded depth of the steel pipe sheet piles that make up the steel pipe sheet pile row 3 may be shallower than the embedded depth of the retaining wall 2, specifically the steel pipe sheet piles 21 that make up the retaining wall 2.

As shown in FIG. 3, in the support pile structure 4, the jacket leg 42 fits onto the outside of the head of the steel pipe sheet pile 31. The steel pipe sheet pile 31 located at the end of the steel pipe sheet pile row 3 opposite the retaining wall 2 and the adjacent steel pipe sheet pile are connected by a joint, for example, as described below. However, at the head of the steel pipe sheet pile 31 to which the jacket leg 42 fits onto the outside, no joint is formed between the adjacent steel pipe sheet pile (steel pipe sheet pile 32, or in another example, steel pipe sheet pile 33) or the retaining wall 2 (when the steel pipe sheet pile row is composed of a single steel pipe sheet pile), and a gap is left between the steel pipe sheet pile 31 and the adjacent steel pipe sheet pile or the retaining wall, making it easier to install the jacket leg 42.

Figure 4 is a diagram showing an example of a joint that can be used in the quay wall structure shown in Figure 1. In the illustrated example, the joint 34 between two steel pipe sheet piles included in the steel pipe sheet pile row 3 includes a pair of female joint members 341 protruding from the peripheral surface of one steel pipe sheet pile and a pair of male joint members 342 protruding from the peripheral surface of the other steel pipe sheet pile. The joint space surrounded by fitting the joints 34 between the steel pipe sheet piles, that is, the space surrounded by the female joint member 341, the male joint member 342, and each steel pipe sheet pile 31 and the peripheral surface of the steel pipe sheet pile 32 or the steel pipe sheet pile 33, 21, is filled with a filler material 343. Specifically, the female joint member 341 and the male joint member 342 are formed of, for example, angle steel. The filler material 343 can be mortar, cement, concrete, or the like. Such joints allow horizontal compressive and shear loads to be transmitted between steel pipe sheet piles.

Furthermore, in this embodiment, the joint 34 has slip stoppers 344A, 344B. The slip stoppers 344A, 344B protrude from the peripheral surface of the steel pipe sheet pile between a pair of female joint members 341 or a pair of male joint members 342 into the joint space and are fixed to the filler 343, so that the vertical shear load is more reliably transmitted between the steel pipe sheet piles. By arranging the slip stoppers 344A, 344B, it is possible to more reliably prevent the occurrence of positional displacement due to vertical shear between the steel pipe sheet piles constituting the steel pipe sheet pile row 3, and to allow the steel pipe sheet pile row 3 to behave as an integral wall body. Note that the slip stoppers 344A, 344B may be, for example, ribs extending horizontally as shown in the figure, or may be beads protruding in a point-like shape.

The joints 34 as described above may be arranged not only between the steel pipe sheet piles that make up the steel pipe sheet pile row 3, but also between the steel pipe sheet piles 31 and the steel pipe sheet piles 21 of the earth retaining wall 2. In addition, although not shown, the integrity of the wall body W may be improved by fixing the heads of the steel pipe sheet piles that make up the steel pipe sheet pile row 3 and the steel pipe sheet piles 21 that make up the earth retaining wall 2 with copings.

Figure 5 is a diagram for explaining the embedment depth of the earth retaining wall in the quay wall structure shown in Figure 1. In this embodiment, the embedment depth of the steel pipe sheet piles 21 constituting the earth retaining wall 2 can be set deeper than the depth d1 at which the backside earth pressure, i.e., the active earth pressure P1 that the earth retaining wall 2 receives from the land-side ground G, and the passive earth pressure P2 that the earth retaining wall receives from the seabed ground, are balanced. In addition, from the perspective of increasing the burden on the earth retaining wall and reducing the load borne by the supporting structure, it is desirable to set the embedment depth of the steel pipe sheet piles 21 deeper than the depth d2 at which the moment around the head of the earth retaining wall 2 is balanced. For example, there is also the idea of embedding the earth retaining wall to a depth equal to or greater than the first zero point of the bending moment when the earth retaining wall is assumed to be a self-supporting structure.

On the other hand, the steel pipe sheet pile row 3, excluding the steel pipe sheet pile 31, does not need to be embedded because its role is to transmit the load to the steel pipe sheet pile 31. For example, one approach is to embed it only 1 to 2 m below the ground surface. In addition, joints do not need to be attached along the entire length, and even if the part protrudes from the ground, joints can be attached only to the necessary parts, and there may be parts without joints.

Next, an example of a construction method of a quay wall structure according to this embodiment will be described in brief. First, the steel pipe sheet piles 21 of the earth retaining wall 2 are sequentially cast while being connected to each other, and then the steel pipe sheet piles of the steel pipe sheet pile row 3 are sequentially cast while being connected to the steel pipe sheet pile 21 for the first one, and then the second and subsequent steel pipe sheet piles are sequentially cast while being connected to each other for the second and subsequent ones. For example, the steel pipe sheet piles of the steel pipe sheet pile row 3 may be cast after the steel pipe sheet piles 21 constituting the entire earth retaining wall 2 are cast, or the steel pipe sheet piles of the steel pipe sheet pile row 3 may be cast in parallel with or before or after the casting of the steel pipe sheet piles 21 of the above-mentioned section S1. The steel pipe sheet pile 31 located at the end of the steel pipe sheet pile row 3 opposite the earth retaining wall 2 is connected to the adjacent steel pipe sheet pile or the earth retaining wall 2 using a joint such as that described above with reference to FIG. 4. In this case, the steel pipe sheet pile 31 is driven while fitting the joint between the adjacent steel pipe sheet pile or the steel pipe sheet pile 21 of the earth retaining wall 2. Alternatively, the steel pipe sheet pile 31 may be driven first, and then the other steel pipe sheet piles in the steel pipe sheet pile row 3 may be driven while adjusting the positions thereof so as to connect the steel pipe sheet pile 21 and the steel pipe sheet pile 31 located at the end of section S1.

After the steel pipe sheet pile 31 is cast, the jacket structure including the jacket leg 42, the beam 6, and the jacket leg 52 is installed on the steel pipe sheet pile 31, and the backing pile 51 is driven using the jacket leg 52 as a guide. As another example, the jacket structure (jacket leg 42, beam 6, and jacket leg 52) may be installed in advance using temporary piles, and the steel pipe sheet pile 31 and the backing pile 51 may be driven using the jacket legs 42 and 52 as guides. By any of the above steps, the steel pipe sheet pile 31 located at the end of the steel pipe sheet pile row 3 opposite the earth retaining wall 2 is incorporated into the support pile structure 4. A superstructure (not shown) constituting the apron part of the quay may be installed above the jacket structure. In addition, since the steel pipe sheet pile row 3 can be constructed independently of the earth retaining wall 2 after the construction of the earth retaining wall 2, the steel pipe sheet pile row 3 may be additionally constructed to reinforce the existing linear earth retaining wall 2, forming the quay wall structure 1 according to this embodiment.

In the first embodiment of the present invention described above, as already explained, the retaining wall 2, which has bending resistance against back earth pressure, and the steel pipe sheet pile array 3 behave integrally as a U-shaped wall W against the ground G. The second moment of area of the wall W is larger than that of the retaining wall 2 alone, and can be easily adjusted by the number of steel pipe sheet piles that make up the steel pipe sheet pile array 3, so that a quay wall structure 1 with the desired bending rigidity against back earth pressure can be easily constructed. In addition, the vertical ground reaction force received by the steel pipe sheet pile array 3 can resist the rotation moment generated in the retaining wall 2 by the back earth pressure. Therefore, in this embodiment, the load borne by the support structure can be reduced while suppressing an increase in the amount of steel material.

Furthermore, in this embodiment, since the steel pipe sheet piles of the steel pipe sheet pile row 3 do not constitute an earth retaining wall, it is not necessary to connect the steel pipe sheet piles 31, 32, 33, 21 with joints over the entire length in the depth direction. Therefore, as described above, no joints are formed in the upper part between the steel pipe sheet pile 31 located at the end of the steel pipe sheet pile row 3 and the adjacent steel pipe sheet piles 32, 33 or the earth retaining wall 2, and by leaving a gap around the steel pipe sheet pile 31, construction of the jacket leg 42 can be made easier.

In addition, in this embodiment, since the earth retaining wall 2 has bending resistance against backside earth pressure, the members constituting the earth retaining wall 2, i.e., the steel pipe sheet piles 21, also have bending rigidity. By constructing the earth retaining wall 2 from members with bending rigidity in this way, for example, bending of each member when cast into the ground can be reduced, and the workability of the earth retaining wall 2 is improved.

In other embodiments, as the retaining wall 2, which has bending resistance against back earth pressure, a retaining wall made of, for example, steel sheet piles, H-shaped steel, or reinforced concrete is used. For these retaining walls, by forming a connecting structure with the steel pipe sheet piles of the steel pipe sheet pile row 3 at both ends of at least a portion of the wall surface direction, the same effect as the quay wall structure 1 according to the first embodiment can be obtained.

Figure 6 is a graph showing the results of calculating the displacement against the total load by the finite element method (FEM) between the quay wall structure (Example) according to the first embodiment of the present invention described above and a Comparative Example that does not include a steel pipe sheet pile row. In the Example and Comparative Example described below, steel pipe sheet piles with a diameter of 1100 mm and a pipe thickness of 12 mm were used. In the Example, nine steel pipe sheet piles were connected to each other to construct a retaining wall with a width of 10 m, and a steel pipe sheet pile row including three steel pipe sheet piles arranged in a direction perpendicular to the wall surface direction of the retaining wall was connected to each of the steel pipe sheet piles at both ends of the retaining wall. The steel pipe sheet piles located at the end opposite the retaining wall among the steel pipe sheet pile rows are connected to the retaining pile structure via jacket legs and beams. On the other hand, in the Comparative Example, nine steel pipe sheet piles were connected to each other to construct a retaining wall with a width of 10 m, and the steel pipe sheet piles at both ends of the retaining wall were connected to the retaining pile structure via jacket legs and beams without placing a steel pipe sheet pile row. In both the examples and the comparative examples, copings were installed at the heads of the steel pipe sheet piles that make up the retaining wall and the steel pipe sheet pile row, so that vertical displacement would not occur between the steel pipe sheet piles.

In both the example and the comparative example, the ground surface on the land side coincided with the upper end of the steel pipe sheet pile, and the embedded depth of the support pile and the backing pile based on the ground surface on the land side was 46.3 m, and the embedded depth of the steel pipe sheet pile was 32.5 m. The distance from the upper end of the steel pipe sheet pile to the seabed was 16.9 m. The lower ends of the steel pipe sheet pile and the backing pile to which the jacket leg was attached were pin supports that did not cause vertical displacement, and the passive earth pressure from the sea side acting on the underground part of the earth retaining wall was set. In addition, the length of the jacket leg of the support pile structure was 5.4 m. Under the above conditions, the relationship between the total load of the active earth pressure from the land side acting on the earth retaining wall and the displacement occurring at the upper end (pier shoulder) of the backing pile structure is shown in the graph in Figure 6. As shown in the graph, the results of FEM calculations showed that in the embodiment in which a U-shaped wall is formed by an earth retaining wall and a row of steel pipe sheet piles, displacement for the same total load is reduced by approximately 17% compared to the comparative example in which a linear wall is formed only by an earth retaining wall.

Next, we will verify the effect of improving the bending rigidity of the wall in an embodiment of the present invention. Table 1 shows the ratio of steel weight and bending rigidity EI per cross section in the example and two comparative examples. Note that the width of the retaining wall and the steel pipe sheet pile row is the distance between the centers of the steel pipe sheet piles at both ends of each. The bending rigidity EI and steel weight ratio are expressed as a ratio with the example being 1.

In the examples, a U-shaped wall is formed by an earth retaining wall and a row of steel pipe sheet piles, whereas in the comparative examples, a straight wall is formed by an earth retaining wall only. In comparative example 1, in order to improve the bending rigidity of the wall, the pipe thickness is increased to the manufacturing limit (20 mm) with the same steel pipe diameter as in the examples, but the bending rigidity EI is only 0.14 times that of the examples. On the other hand, in comparative example 2, the manufacturing limit is not taken into consideration, and the steel pipe diameter (2000 mm) and pipe thickness (24 mm) are extremely large to achieve the same bending rigidity EI as in the examples, but the steel weight ratio is 1.96 times that of the examples, which is not practical in terms of manufacturing and is also uneconomical in terms of the amount of steel used.

Figure 7 is a graph showing the results of calculating the load sharing rate of the wall, i.e., the structure consisting of the retaining wall and the steel pipe sheet pile row, when the number N of steel pipe sheet piles constituting the steel pipe sheet pile row is changed for the quay wall structure according to the first embodiment of the present invention described above. If the retaining wall has a sufficient embedded depth as described above, the load sharing rate increases as the number N of steel pipe sheet piles constituting the steel pipe sheet pile row increases, as shown in the graph. By increasing the load sharing rate of the wall consisting of the retaining wall and the steel pipe sheet pile row, the load borne by the support pile structure and the backing pile structure becomes smaller, and it is possible to, for example, reduce the embedded depth of the support piles or reduce the amount of steel material in the members including the beams.

Figure 8 is a cross-sectional view of a quay wall structure according to a second embodiment of the present invention. In addition to the same configuration as in the first embodiment, the quay wall structure 1A according to this embodiment includes a fitting member 43 (also called stabbing) that fits inside the head of one of the steel pipe sheet piles 21 of the multiple steel pipe sheet piles that make up the earth retaining wall 2. In this case, the beam 6 includes a portion (first connecting member) that is arranged between the jacket legs 42 and 52, and a portion (second connecting member) that is arranged between the jacket leg 42 and the fitting member 43. As already mentioned, in other embodiments, an earth retaining wall made of, for example, steel sheet piles, H-shaped steel, or reinforced concrete is used, and in these cases, a beam 6 that is connected to the earth retaining wall by an appropriate method and includes a portion (second connecting member) that connects the jacket leg 42 to the earth retaining wall may be arranged.

The above-mentioned structure can reduce the concentration of member stress and bending moment on the steel pipe sheet pile 31 that functions as part of the support pile structure. If the earth pressure received by the earth retaining wall 2 is transmitted to the support pile structure 4 only by the compressive force acting on each steel pipe sheet pile in the steel pipe sheet pile row 3 or the shear force between the steel pipe sheet piles, even if the force is ultimately borne by the retaining pile structure 5, it is transmitted from the steel pipe sheet pile 31 to the beam 6 via the jacket leg 42, so that the member stress and bending moment acting on the steel pipe sheet pile 31 tend to be large. In contrast, if the earth pressure received by the earth retaining wall 2 is directly transmitted to the jacket legs 42, 52 using the beam 6 as in the above example, the force borne by the retaining pile structure 5 is transmitted to the beam 6 without passing through the steel pipe sheet pile 31, so that the member stress and bending moment acting on the steel pipe sheet pile 31 can be reduced. In addition, by extending the beam 6 to the earth retaining wall 2, a flat foundation is formed on the upper surface of the quay wall structure 1A, making it easier to install superstructures such as deck slabs.

Furthermore, by reducing the compressive force acting on the steel pipe sheet piles of the steel pipe sheet pile row 3 and the shear force between the steel pipe sheet piles, the design of the steel pipe sheet piles (steel pipe sheet piles 32, 33) and joints that make up the steel pipe sheet pile row 3 is also made easier. Specifically, in this embodiment, the steel pipe sheet piles 32, 33 arranged between the earth retaining wall 2 and the steel pipe sheet pile 31 can be arranged with their heads separated from the beam 6 (part of the second connecting member). This is because, when the beam 6 is not extended, a large force due to the earth pressure of the earth retaining wall 2 is transmitted through the upper part of the steel pipe sheet piles 32, 33, so the heads need to be at the same height as the earth retaining wall 2 and the steel pipe sheet pile 31, whereas when the beam 6 is connected to the earth retaining wall 2, the force is transmitted through the beam 6, so there is no need to extend the heads of the steel pipe sheet piles 32, 33 to the same height as the beam 6. The heads of the steel pipe sheet piles 32, 33 can be, for example, 5 to 6 m lower than the steel pipe sheet pile 31. This not only saves on the amount of steel used, but by burying the steel pipe sheet piles 32, 33 in the ground up to their tops, it is possible to omit the anti-corrosion coating that is required when steel members are exposed to the ground surface near the coast.

9A and 9B are diagrams showing the displacements calculated by frame analysis for the quay wall structures (Example 1 and Example 2) according to the first and second embodiments of the present invention. The analysis conditions are as follows. The steel pipe sheet piles 21 constituting the earth retaining wall 2 and the steel pipe sheet piles 32 and 33 constituting the steel pipe sheet pile row 3 have a diameter of 1100 mm, a pipe thickness of 16 mm, a length of 27.9 m, and an embedded depth of 11 m. The reaction coefficients of the joints, which are spring elements, are 49033 kN/m ² for compression and 588397 kN/m ² for shear. The steel pipe sheet piles 31, which also function as a support pile structure, have a diameter of 1100 mm, a pipe thickness of 12 mm, a length of 46.3 m, and an embedded depth of 29.4 m. The length of the jacket leg 42 is 5.4 m, and the pipe thickness is 50 mm in the section where the jacket leg 42 is fitted to the steel pipe sheet pile 31. The support pile 51 had a diameter of 1800 mm, a pipe thickness of 30 mm, a vertical height of 46.6 m, and a vertical embedment depth of 30.2 m. The vertical height of the jacket leg 52 was 14.3 m, and the pipe thickness was calculated as 54 mm in the section where the jacket leg 52 fits into the support pile 51. H-shaped steel of HY800 x 400 x 16 x 32 was used for the beam 6. In addition, the beam 6 close to the jacket leg 42 and the vicinity of the tip of the jacket leg 52 were connected by a brace using a steel pipe with a diameter of 1016 mm and a pipe thickness of 12.7 mm. In Example 1, the beam 6 was not extended beyond the jacket leg 42 toward the earth retaining wall, whereas in Example 2, the beam 6 was extended beyond the jacket leg 42 and connected to the earth retaining wall 2 as shown in FIG. 8.

Under the above conditions, a total of 2340 kN of earth pressure acts on the area from the top of the earth retaining wall 2 to a depth of 13.8 m, and a stress of 21.86 kN/ ^m2 is applied to the top surface of the quay wall structure by the weight of the upper structure and the live load. The top surface of the quay wall structure is supported by the beam 6 and the steel pipe sheet piles 32, 33 in Example 1, and by the beam 6 in Example 2. Figures 9A and 9B show the displacement in the vertical cross section enlarged 20 times, respectively, with the amount of displacement expressed by the color depth in the cases of Example 1 and Example 2. As shown in these figures, in Example 2 in which the jacket leg 42 and the earth retaining wall 2 are connected by the beam 6, the concentration of the amount of displacement at the top of the earth retaining wall 2 and the steel pipe sheet pile row 3 is alleviated compared to Example 1 in which the jacket leg 42 and the earth retaining wall 2 are not connected, and the displacement is distributed over the whole area. In Example 1, a maximum bending moment of 156.2 kN/m occurred in the steel pipe sheet pile 31 at the position indicated by the arrow in FIG. 9A, but in Example 2, this was reduced to 78.3 kN/m.

In addition to the above examples 1 and 2, the stress intensity (UC) of each member was calculated for two examples in which the heads of the steel pipe sheet piles 32, 33 were lower than the beam 6 under the same conditions. Specifically, analysis was performed for an example (example 3) in which the heads of the steel pipe sheet piles 32, 33 were 1 m lower than the beam 6, and an example (example 4) in which the heads were 6 m lower. The results are shown in Table 1. In the table, "back pile leg" means the jacket leg 52, and "support pile leg" means the jacket leg 42. "Support pile" means the steel pipe sheet pile 31. Also, "steel pipe sheet pile" means the maximum stress intensity among the steel pipe sheet piles 32, 33 that make up the steel pipe sheet pile row.

As can be seen from the results shown in Table 2 above, by connecting the jacket legs to the retaining wall, the stress on the support piles (steel pipe sheet piles 31) and the steel pipe sheet piles (steel pipe sheet piles 32, 33) that make up the steel pipe sheet pile row can be distributed to the support piles, and in particular, the stress level generated in the support piles can be reduced by more than half. This effect can also be obtained when the heads of the steel pipe sheet piles are lower than the beams.

The above describes in detail preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to such examples. It is clear that a person with ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

1, 1A...quay wall structure, 2...earth retaining wall, 21...steel pipe sheet pile, 3...row of steel pipe sheet piles, 31...steel pipe sheet piles (support piles), 32, 33...steel pipe sheet piles, 34...joint, 341...female joint member, 342...male joint member, 343...filler, 344A, 344B...slip stopper, 4...support pile structure, 42...jacket leg, 5...support pile structure, 51...support pile, 52...jacket leg, 6...beam, S1...section, W...wall.

Claims (16)

A retaining wall having bending resistance against back earth pressure;
and a steel pipe sheet pile row including at least two steel pipe sheet piles arranged in a direction intersecting the wall surface direction from both ends of at least a portion of the wall surface direction of the earth retaining wall and connected to each other by fitting with joints ,
The first steel pipe sheet pile located at the end of the steel pipe sheet pile row opposite the earth retaining wall functions as at least a part of a support pile structure. A retaining wall having bending resistance against back earth pressure;
a steel pipe sheet pile row including at least one steel pipe sheet pile arranged in a direction intersecting the wall surface direction from both ends of at least a portion of a wall surface direction of the earth retaining wall;
Equipped with
The first steel pipe sheet pile located at the end of the steel pipe sheet pile row opposite the earth retaining wall functions as at least a part of a support pile structure,
The steel pipe sheet pile row is a quay wall structure including a second steel pipe sheet pile connected to the retaining wall, and at least one third steel pipe sheet pile adjacent to the second steel pipe sheet pile in a direction intersecting the wall surface direction and connected to the second steel pipe sheet pile by fitting it with a joint. The quay wall structure according to claim 1 or 2, wherein the steel pipe sheet pile rows are arranged on the sea side of the ground, sandwiching the retaining wall. The quay structure according to any one of claims 1 to 3, further comprising a support pile structure located on the seaward side of the support pile structure, and a connecting member connecting the support pile structure to the support pile structure. The support pile structure includes the first steel pipe sheet pile and a first jacket leg fitted to the outside of a head of the first steel pipe sheet pile,
The bail structure includes a bail and a second jacket leg that fits onto an outer side of a head of the bail;
The quay wall structure according to claim 4 , wherein the connecting members include a first connecting member disposed between the first jacket leg and the second jacket leg. The quay wall structure according to claim 5, wherein no joint is formed between the head of the first steel pipe sheet pile and the adjacent steel pipe sheet pile or the retaining wall, and the first jacket leg is fitted from the outside into the portion where no joint is formed. The quay wall structure according to claim 5 or 6, wherein the connecting member includes a second connecting member that connects the first jacket leg to the retaining wall. The retaining wall is composed of a plurality of steel pipe sheet piles connected to each other,
The quay wall structure includes a fitting member that fits into an inside of a head portion of one of the plurality of steel pipe sheet piles,
The quay wall structure according to claim 7, wherein said second connecting member is disposed between said first jacket leg and said mating member. The steel pipe sheet pile row includes at least one fourth steel pipe sheet pile arranged between the retaining wall and the first steel pipe sheet pile,
The quay wall structure according to claim 7 or 8, wherein a head portion of the fourth steel pipe sheet pile is spaced apart from the second connecting member. The quay wall structure according to any one of claims 1 to 9, in which a stopper protrudes from the periphery of the steel pipe sheet piles in a joint space enclosed by fitting the joints of the steel pipe sheet piles included in the steel pipe sheet pile row, and the joint space is filled with a filler material. The quay wall structure according to any one of claims 1 to 10, wherein the retaining wall is composed of a plurality of steel pipe sheet piles connected to each other, and the ends of the steel pipe sheet pile rows on the retaining wall side are connected to the steel pipe sheet piles located at both ends of the section. The quay wall structure according to claim 11, in which the heads of the steel pipe sheet piles constituting the steel pipe sheet pile row and the steel pipe sheet piles constituting the earth retaining wall are fixed by copings. The quay wall structure according to any one of claims 1 to 12, wherein the embedded depth of the steel pipe sheet piles constituting the steel pipe sheet pile row is shallower than the embedded depth of the earth retaining wall. A step of constructing an earth retaining wall having bending resistance against back earth pressure;
A process of constructing a steel pipe sheet pile row by arranging at least two steel pipe sheet piles connected to each other by fitting them together with joints in a direction intersecting the wall surface direction from both ends of at least a portion of the wall surface direction of the retaining wall;
and incorporating a first steel pipe sheet pile located at an end of the row of steel pipe sheet piles opposite the earth retaining wall into a support pile structure. A step of constructing an earth retaining wall having bending resistance against back earth pressure;
A step of constructing a steel pipe sheet pile row by arranging at least one steel pipe sheet pile in a direction intersecting the wall surface direction from both ends of at least a portion of a wall surface direction of the retaining wall;
a step of incorporating a first steel pipe sheet pile located at an end of the steel pipe sheet pile row opposite to the earth retaining wall into a support pile structure;
Including,
The step of incorporating the first steel pipe sheet pile into the support pile structure includes a step of fitting a first jacket leg to an outer side of a head portion of the first steel pipe sheet pile,
The method for constructing a quay structure further comprises a step of driving a backing pile on the sea side of the first steel pipe sheet pile using a second jacket leg connected to the first jacket leg via a connecting member as a guide. A step of constructing an earth retaining wall having bending resistance against back earth pressure;
A step of constructing a steel pipe sheet pile row by arranging at least one steel pipe sheet pile in a direction intersecting the wall surface direction from both ends of at least a portion of a wall surface direction of the retaining wall;
a step of incorporating a first steel pipe sheet pile located at an end of the steel pipe sheet pile row opposite to the earth retaining wall into a support pile structure;
Including,
installing a first jacket leg, a second jacket leg located seaward of the first jacket leg, and a connecting member connecting the first jacket leg to the second jacket leg;
and driving a pier using the second jacket leg as a guide.
A method for constructing a quay structure, wherein the step of incorporating the first steel pipe sheet pile into a support pile structure includes the step of driving the first steel pipe sheet pile using the first jacket leg as a guide.

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