Revetment structure, and construction method of revetment structure

Abstract

To provide a revetment structure and a construction method of a revetment structure that can easily and efficiently reinforce the entire revetment area to improve ground strength, simplify a structure of a revetment wall, such as an embedded length, and also contribute to reducing CO2 at a construction site.SOLUTION: A revetment structure is constructed by connecting a steel sheet pile 3 and a stay member 4 with a plurality of tie rods 5. A plurality of logs 2 are placed in a soft ground G1, G2 on at least one of a land side area R1 between the steel sheet pile 3 and the stay member 4 and a water side area R2 at a water side of the steel sheet pile 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a revetment structure and a construction method for the revetment structure. [Background technology]

[0002] Conventionally, a known revetment structure is one that is composed of a revetment wall and supporting members on the land side. The revetment wall is located at the boundary between the water body and the land, and resists deformation by being embedded in the water body and installed deeper than the bottom of the water body. Furthermore, a revetment structure is known in which the top of the wall structure is connected to a supporting structure installed on the land side by rod-shaped members, and has a mechanism for suppressing deformation of the top (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-332713 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional revetment structure has the following problems. In other words, when it is necessary to increase the water depth of the revetment wall or strengthen its earthquake resistance, the specifications of the wall structure must be strengthened due to insufficient resistance at the embedded parts of the existing wall structure or increased earth pressure from the land side. Furthermore, even when constructing a new revetment structure, the resistance and rigidity required of the wall structure increases depending on the water depth of the quay. This requires that the wall components have high cross-sectional performance and are long, which creates problems such as increased weight, and there is room for improvement in this regard. Therefore, in order to increase the strength of the ground around the embedded part of the wall structure, soil improvement methods such as replacing the ground with improved soil that can increase the ground strength more than the original ground or using cement are used. However, with conventional ground improvement methods, such as sand compaction piles, the increase in shear resistance is limited, and when construction space is limited, large heavy machinery is used, which requires space for assembly and disassembly, leaving room for improvement.In addition, when cement is used, a cement plant must be installed, and when construction involves earthwork, large pouring machinery is required, which requires securing a large construction yard and lengthens the construction period, posing problems in terms of workability. Furthermore, reducing CO2 emissions as a measure against global warming is an urgent issue in the construction industry, which emits a lot of CO2, and there was room for improvement in ground improvement methods that require large heavy machinery that consumes a lot of fuel and emits large amounts of CO2.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a revetment structure and a construction method for a revetment structure that can easily and efficiently reinforce the entire revetment to improve ground strength, simplify the structure such as the embedded length of the revetment wall, improve workability by reducing the construction space and construction period, and also contribute to reducing CO2 emissions at construction sites. [Means for solving the problem]

[0006] (1) Aspect 1 of the revetment structure of the present invention is a revetment structure constructed by connecting a revetment wall body and a support member with a plurality of connecting members, characterized in that a plurality of logs are provided in the soft ground in at least one of a first region between the support members of the revetment wall body and a second region on the water side of the revetment wall body.

[0007] In this invention, because the ground is divided by the revetment wall, lateral ground movement, which is the left-right direction shown on the paper, is easily restricted. Therefore, by placing logs in the ground and spreading out the surrounding ground, the density of the ground between the logs and the revetment wall increases, which has the effect of improving the ground strength. Furthermore, by adding logs to the soft ground in the first area on the land side and the second area on the water side, the ground resistance at the embedded portion of the revetment wall is increased, improving seismic resistance. This also allows for a relatively shorter embedded length compared to conventional revetment structures without logs. Furthermore, because the shear stiffness and shear resistance of the denser ground increase, the cross-sectional performance required for the revetment wall, which is supported by the resistance of the ground, can be reduced. In this way, the present invention simplifies the structure by shortening the embedded length of the revetment wall and using materials with lower rigidity. This means that the specifications for the revetment wall can be set lower, leading to reduced costs for the revetment wall materials.

[0008] In addition, in this invention, by using dried wood as logs, after the logs are placed, they absorb water from the surrounding ground, reducing the pore water pressure in the surrounding ground, increasing the unsaturated ground area, and increasing the strength of the entire ground due to the negative pressure. In addition, a drying process and a preservative treatment process may be included before placing the logs. Furthermore, when materials manufactured in factories are used as reinforcement, a certain production period may be required after receiving an order, and they may need to be stored indoors to ensure quality. However, logs, due to their shape, can be easily stacked and stored, resulting in good space-saving efficiency. They can also be stored outdoors, and no storage building is required, making them suitable for stockpiling as a regular lumber supply, allowing materials to be delivered as needed and supplied immediately when needed, such as in disaster response, and allowing for more flexible response to construction period conditions than conventional construction methods. Furthermore, in this invention, the ground that contributes to the stability of the revetment wall is reinforced with logs, so all that is needed is space for heavy machinery to drive the logs into the ground, which has the advantage of eliminating the need for a large construction yard as in the case of ground improvement methods.

[0009] Furthermore, the present invention has the advantage that carbon dioxide absorbed from the atmosphere by multiple logs can be stored inside the ground, which contributes to reducing CO2 emissions at construction sites and contributing to carbon neutrality.

[0010] (2) In a second aspect of the present invention, in the revetment structure of the first aspect, it is preferable that the logs are driven into the soft ground.

[0011] In this case, in conditions where the soft ground in the first area is blocked by the wall structure of the revetment wall and the retaining members, driving logs directly into the soft ground has the effect of improving the ground by increasing the restraining force through compaction, thereby also increasing the resistance force of the retaining members.

[0012] (3) A third aspect of the present invention may be characterized in that, in the revetment structure of the first aspect, the logs are provided by replacing a part of the soft ground.

[0013] In this case, after a portion of the soft ground is excavated first, logs are placed in the excavated holes, which is a replacement method, so the weight (density) of the ground in the improved area can be reduced. This reduces the active earth pressure acting on the revetment wall. Also, by making the diameter of the excavated holes smaller than the diameter of the logs, it is possible to achieve both the effect of improving ground strength by spreading it out and the effect of reducing the weight of the ground.

[0014] (4) A fourth aspect of the present invention may be characterized in that, in the revetment structure of any one of the first to third aspects, the lower end of at least one of the plurality of logs is deeper than the lower end of the revetment wall.

[0015] In the present invention, the logs reach deeper into the ground beyond the lower end of the revetment wall, steadily increasing the shear rigidity and shear resistance of the ground portion around the lower part of the revetment wall, which is particularly important for supporting the revetment wall. This further reduces the earth pressure acting on the revetment wall from the ground behind it and increases the ground resistance supporting the revetment wall, thereby reducing the length and rigidity required for the revetment wall.

[0016] (5) Aspect 5 of the present invention is characterized in that, in the revetment structure of any one of aspects 1 to 4, the revetment wall is formed of steel, and the amount of carbon dioxide stored in all of the multiple logs is greater than the amount of carbon dioxide emitted during the manufacture of the revetment wall.

[0017] In the present invention, the amount of carbon dioxide stored in all of the multiple logs is greater than the amount of carbon dioxide emitted during the manufacturing of the revetment wall, which leads to a reduction in the amount of CO2 in the atmosphere and provides an environmentally friendly revetment structure.

[0018] (6) A sixth aspect of the present invention may be characterized in that, in the revetment structure of any one of the first to fifth aspects, the plurality of logs are driven into the structure so that a tensile force is applied to the connecting member.

[0019] In the present invention, the logs can apply tensile force to the connecting member, thereby increasing the restraining force on the soft ground in the first area between the revetment wall and the supporting member, thereby achieving a more reliable improvement effect.

[0020] (7) Aspect 7 of the present invention is characterized in that, in any one of aspects 1 to 6 of the revetment structure, the lower end of the log is located at a position deeper than at least one of a first passive collapse line drawn from the lower end of the revetment wall at a passive collapse angle toward the soft ground in the first area and a second passive collapse line drawn from the lower end of the revetment wall at a passive collapse angle toward the soft ground in the second area.

[0021] In the present invention, logs cross at least one of the first passive collapse line and the second passive collapse line, and therefore the shear resistance of the logs, which are larger than the ground, is added, thereby increasing the shear resistance of the entire passive collapse line. In addition to the effect of increasing ground strength due to the increase in density of the surrounding ground caused by the installation of logs, the ground strength that efficiently supports the revetment wall can be improved.

[0022] (8) Aspect 8 of the present invention is characterized in that, in any one of aspects 1 to 7 of the revetment structure, the logs are inclined so as to extend downward from the head of at least one of the revetment wall body and the supporting member toward the other.

[0023] In the present invention, the heads of at least one of the revetment wall and the supporting member are supported by inclined logs, and loads that would deform these heads are resisted by compressive force caused by tension in the logs, thereby suppressing deformation of at least one of the revetment wall and the supporting member.

[0024] (9) Aspect 9 of the present invention is characterized in that, in the revetment structure of any one of aspects 1 to 8, at least one of the revetment wall, the support member, and the log is cast to a position deeper than the liquefaction layer.

[0025] In the present invention, by driving the revetment wall and the lower ends of the logs into stronger ground deeper than the liquefaction layer where liquefaction will not occur, the revetment wall can be made to have increased resistance to the soil and water pressure acting from the liquefaction layer, and the logs can be made to have increased surrounding ground strength across the entire thickness of the liquefaction layer, and can be kept in place without their installation position being affected by the load from the liquefaction layer.

[0026] (10) Aspect 10 of the construction method for a revetment structure according to the present invention is characterized by having the steps of connecting a revetment wall body and a support member with a plurality of connecting members, and placing a plurality of logs on the soft ground in at least one of a first region between the support members of the revetment wall body and a second region on the water side of the revetment wall body.

[0027] In the present invention, a revetment structure that can achieve the effects of the first aspect described above can be constructed.

[0028] (11) An eleventh aspect of the present invention is characterized in that, in the construction method for a revetment structure of the tenth aspect, the logs are driven into the soft ground.

[0029] In the present invention, in conditions where the soft ground in the first area is blocked by the wall structure of the revetment wall and the retaining members, an improvement effect is achieved by directly driving logs into the soft ground, which increases the restraining force through compaction, thereby also increasing the resistance force of the retaining members.

[0030] (12) Aspect 12 of the present invention is characterized in that, in the construction method for a revetment structure of aspect 10, it includes a step of pre-excavating the soft ground at the position where the log is to be installed to create a driving hole, and a step of burying the log in the driving hole to replace it.

[0031] This method involves excavating a portion of the soft ground first, then placing logs in the excavated holes, which reduces the weight (density) of the ground in the improved area. This reduces the active earth pressure acting on the revetment wall. Furthermore, by making the diameter of the excavated holes smaller than the diameter of the logs, it is possible to achieve both the effect of improving ground strength by spreading the ground and the effect of reducing the ground weight. [Effects of the Invention]

[0032] The revetment structure and construction method for the revetment structure of the present invention enable reinforcement to be carried out easily and efficiently over the entire revetment area to improve ground strength, simplifying the structure, such as the embedded length of the revetment wall, and contributing to reducing CO2 emissions at construction sites. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a side view showing a revetment structure according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the revetment structure shown in FIG. [Figure 3] FIG. 10 is a partial perspective view of a revetment structure according to a first modified example. [Figure 4] FIG. 4 is a side view showing the connection state between the logs and the connecting horizontal members of the revetment structure shown in FIG. 3. [Figure 5] FIG. 10 is a partial perspective view of another revetment structure of the first modified example. [Figure 6] FIG. 4 is a side view showing the connection state between the logs and the connecting horizontal members of the revetment structure shown in FIG. 3. [Figure 7] (a) and (b) show the relationship between the improvement rate and CO2 storage capacity in logs. [Figure 8] FIG. 10 is a side view showing a revetment structure according to a second embodiment. [Figure 9] FIG. 10 is a side view showing a revetment structure according to a second embodiment. [Figure 10] FIG. 10 is a side view showing a revetment structure according to a second embodiment. [Figure 11] FIG. 10 is a side view showing a revetment structure according to a third embodiment. [Figure 12] FIG. 10 is a side view showing a revetment structure according to a second modified example. [Figure 13] FIG. 10 is a side view showing a revetment structure according to a fourth embodiment. [Figure 14] FIG. 10 is a side view showing a revetment structure according to a third modified example. [Figure 15] FIG. 10 is a side view showing a revetment structure according to a fifth embodiment. [Figure 16] FIG. 10 is a partial perspective view of another reinforcing structure. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, a revetment structure and a construction method for the revetment structure according to an embodiment of the present invention will be described with reference to the drawings.

[0035] (First embodiment) As shown in Figures 1 and 2, the revetment structure 1 according to this first embodiment is constructed by connecting steel sheet piles 3 (revetment wall body) and support members 4 with multiple tie rods 5 (connecting members), and is a structure in which soft ground G that is at risk of liquefaction is reinforced by multiple logs 2. The revetment structure 1 may be applied to a reinforcement structure in which an existing structure consisting of steel sheet piles 3, support members 4, and multiple tie rods 5 is reinforced with multiple logs 2, or to a newly constructed structure in which steel sheet piles 3, support members 4, multiple tie rods 5, and multiple logs 2 are installed at the same time.

[0036] The revetment structure 1 has multiple logs 2 laid on soft ground G1 and G2 in the land-side area R1 (first area) between the steel sheet pile 3 and the support member 4, and in the water-side area R2 (second area) from the revetment wall 3.

[0037] The steel sheet piles 3 are buried in soft ground G1 on the land side and extend in a direction (extension direction X2) that is approximately perpendicular to the normal direction of the quay wall (front-to-back direction X1) in a plan view. The steel sheet piles 3 are, for example, hat-shaped steel sheet piles, and are constructed by driving multiple steel sheet piles continuously and integrally into the soft ground G1 in the extension direction X2.

[0038] For example, steel sheet piles or steel pipe piles are used as the support members 4. The support members 4 are driven into the soft ground G1 at intervals on the landward side of the steel sheet piles 3, and are provided at multiple locations at predetermined intervals along the extension direction X2.

[0039] The tie rods 5 extend in the front-to-rear direction X1, connect the heads of the steel sheet piles 3 and the support members 4, and apply tensile force to the steel sheet piles 3 and the support members 4. A plurality of tie rods 5 are arranged at predetermined intervals (for example, 2 m intervals) in the extension direction X2, and are each located at a predetermined depth from the ground surface. The number and spacing of the tie rods 5 can be changed as appropriate depending on the strength of the soft ground G1, the structure of the support members 4, and the like.

[0040] The logs 2 are made of wood such as larch. The logs 2 have a roughly circular cross section and are installed by driving into the soft ground G1 on the land side and the soft ground G2 on the water side, or by replacing part of the soft ground G1, G2. These multiple logs 2 are driven so that tension is applied to the tie rods 5. The logs 2 installed on the water side are positioned closer to the steel sheet piles 3. The diameter and overall length of the logs 2 can be changed as appropriate. It is also preferable that the lower ends of the logs 2 be sharpened to facilitate penetration into the ground. The logs 2 can also be made from thinnings or main harvest timber.

[0041] As shown in Figure 2, the multiple logs 2 are arranged in a staggered pattern in plan view. In order to evenly increase the strength of the ground around the logs, it is preferable to maintain a constant distance between the logs, which also makes construction management easier. When installing logs on ground where an existing revetment wall is located, the strength of the surrounding ground increases as the logs are installed, which also increases the driving resistance when driving the logs into the ground. Therefore, by keeping the log spacing even, it is possible to avoid local increases in ground strength and increased driving resistance, and it is possible to drive the logs into the ground with a constant construction machine load. The arrangement of the multiple logs 2 is not limited to a staggered pattern, but may be arranged at regular intervals vertically and horizontally when viewed in a plan view, or may be arranged to form a lattice shape.

[0042] Furthermore, the logs 2 are not limited to those with a circular cross section, and it is also possible to use logs with an angular cross section such as a rectangular cross section.

[0043] At least one of the steel sheet piles 3, the support members 4 and the logs 2 is driven to a position deeper than the liquefaction layer. In the revetment structure 1 of the first embodiment, all of the logs 2 installed in the land-side region R1 have the same length, and all of the logs 2 installed in the water-side region R2 have the same length. The lower ends 2b of the logs 2 installed in the soft ground G1 in the land-side region R1 are located shallower than the lower ends 3b of the steel sheet piles 3 and the lower ends 4b of the support members 4. In cases where it is necessary to increase the ground strength only in the relatively shallow layer of ground surrounding the installation of the steel sheet piles, it is not necessary to lengthen the logs to match the length of the steel sheet piles, and it is preferable to appropriately select the log length so as to minimize costs depending on the installation location. Furthermore, the lower end 2b of the log 2 placed in the soft ground G2 in the water area side region R2 is placed at approximately the same depth as the lower end 3b of the steel sheet pile 3. By positioning the lower end of the log at approximately the same depth as the lower end of the steel sheet pile, the strength of the ground around the steel sheet pile can be increased over the entire length of the steel sheet pile.

[0044] As shown in Figures 3 to 6, the multiple logs 2 can be connected in the front-to-rear direction X1, for example, by connecting horizontal members 20 made of wood. The connecting horizontal members 20 are pieces of wood with a circular cross section similar to the logs 2. The connecting horizontal members 20 connect the heads 2a of the multiple logs 2 together.

[0045] 3 and 4 show an example in which one end 20a of a connecting horizontal member 20 is joined to the head 3a of a steel sheet pile 3. As shown in Fig. 3, the one end 20a of the connecting horizontal member 20 and the head 3a of the steel sheet pile 3 are joined by a wire 21A that penetrates each other. As shown in Fig. 4, the connecting horizontal member 20 and the head 2a of a log 2 are joined by a wire 21B that penetrates each other.

[0046] 5 and 6 show an example in which one end 20a of the connecting horizontal member 20 is joined to the vertical middle portion 3c of the steel sheet pile 3. As shown in Fig. 5, the one end 20a of the connecting horizontal member 20 and the middle portion 3c of the steel sheet pile 3 are joined together using a wire 21C that penetrates the connecting horizontal member 20 and a bracket piece 22 with an L-shaped cross section attached to the side surface of the steel sheet pile 3. Alternatively, as shown in Fig. 6, the one end 20a of the connecting horizontal member 20 and the middle portion 3c of the steel sheet pile 3 may be joined together by a wire 21D that penetrates each other.

[0047] The number of logs 2 is set so that the amount of carbon dioxide (CO2) stored in all of the logs 2 (carbon dioxide storage amount) will be greater than the amount of carbon dioxide emitted during the manufacturing of the steel sheet pile 3. In other words, the amount of carbon dioxide stored in these logs 2 can be determined by setting the improvement rate (%) (= cross-sectional area of ​​the log / planar area of ​​the study area) and length of the logs 2. By using logs 2 made of wood in this revetment structure 1, CO2 can be stored in the logs 2 for a long period of time as long as they are not rotted and remain sound, which can help reduce CO2 in the atmosphere.

[0048] Furthermore, if the carbon emissions during manufacturing are relatively low, for example, because the steel for steel sheet piles is produced in an electric furnace, it may be possible to make the entire revetment reinforcement work carbon-neutral, including the steel sheet pile manufacturing process. Even if this is not the case, it is possible to significantly reduce carbon emissions throughout the entire revetment reinforcement work, including emissions during the manufacturing of revetment wall materials and from construction machinery. In addition, wood needs air and decay fungi to deteriorate, but these are lacking below or near the groundwater level, so the wood remains healthy. Therefore, this invention, in which logs are driven into soft ground below the groundwater level, is effective for storing CO2.

[0049] Figures 7(a) and (b) and Table 1 are an example showing the relationship between the improvement rate (%) and the CO2 storage amount (t) in a log. Figure 7(b) is a partially enlarged view of Figure 7(a). In Figures 7(a) and (b), "T1" indicates the CO2 emissions caused by heavy machinery fuel, "T2" indicates the CO2 emissions caused by steel sheet pile manufacturing in the blast furnace, and "M" indicates the CO2 storage amount in the log 2. "Heavy machinery fuel" refers to the CO2 emitted from the construction heavy machinery used when driving the steel sheet pile 3 into the ground. Table 1 shows the storage rate (kgCO2 / m) of the log 2. 2 ), carbon stock (t) and CO2 equivalent (t). For example, when diesel is 412.8L and the diesel emission coefficient (kgCO2 / L) is 2.62, the CO2 emissions resulting from heavy machinery fuel use are 0.54t.

[0050] [Table 1]

[0051] From Figures 7(a) and (b) and Table 1, if the improvement rate using logs 2 is about 0.5%, it is possible to store CO2 in logs 2 at the same level as the CO2 emissions from heavy machinery. Furthermore, if the improvement rate using logs 2 is about 10%, it is possible to store CO2 in logs 2 at the same level as the CO2 emissions caused by steel sheet pile manufacturing.

[0052] Next, a construction method for the above-mentioned revetment structure 1 will be described. First, as shown in Figures 1 and 2, steel sheet piles 3 and backing members 4 are driven into predetermined positions in the soft ground G1 on the land side. Then, tie rods 5 are installed in the soft ground G1 on the land side between the steel sheet piles 3 and the backing members 4 at a depth of approximately 1 m to 3 m from the ground surface. One end of the tie rod 5 is connected to the head of the steel sheet pile 3, and the other end is connected to the head of the backing member 4. In other words, the steel sheet piles 3 and the backing members 4 are connected by multiple tie rods 5.

[0053] Next, a plurality of logs 2 are laid in soft ground G1, G2 in the land-side area R1 between the support members 4 of the steel sheet piles 3 and in the water-side area R2 on the water side of the steel sheet piles 3. Methods for laying the logs 2 include, for example, driving the logs 2 into the soft ground G using heavy construction machinery, and installing the logs 2 by replacing part of the soft ground G. In the method of replacing part of the soft ground G with the logs 2, first, a part of the soft ground G at the position where the logs 2 are to be laid is pre-excavated to make driving holes, and then the logs 2 are buried in the driving holes to replace them.

[0054] The revetment structure 1 described above is constructed by connecting the steel sheet piles 3 and the support members 4 with a plurality of tie rods 5. The revetment structure 1 has a plurality of logs 2 laid in soft ground G1, G2 in at least one of (here, both of) the land-side area R1 between the steel sheet piles 3 and the support members 4 and the water-side area R2 on the water side of the steel sheet piles 3.

[0055] Therefore, in this embodiment, the ground is partitioned by the steel sheet piles 3, so that lateral ground movement is easily restricted. Therefore, by placing the logs 2 in the ground and spreading out the surrounding ground, the density of the ground between the periphery of the logs 2 and the steel sheet piles 3 increases, and the effect of improving the ground strength can be achieved. Furthermore, by adding logs to the soft ground in the landward area R1 on the land side and the soft ground in the waterward area R2 on the water side in addition to the conventional revetment structure, the ground resistance of the embedded portion of the steel sheet pile 3 is increased, improving seismic resistance. Furthermore, the embedded length can be relatively shorter compared to a conventional revetment structure without logs 2. Furthermore, because the shear stiffness and shear resistance of the soil with increased density are increased, it becomes possible to lower the cross-sectional performance required of the steel sheet pile 3, which is supported by the resistance force from the soil. Thus, in this embodiment, the embedded length of the steel sheet pile 3 can be shortened or a material with low rigidity can be used, simplifying the structure. This means that the specifications of the steel sheet pile 3 can be set lower, leading to a reduction in the cost of the material for the steel sheet pile 3.

[0056] In addition, in this embodiment, by using dried wood as the logs 2, after the logs 2 are installed, they absorb water from the surrounding ground, reducing the pore water pressure in the surrounding ground, increasing the unsaturated ground range, and increasing the strength of the entire ground through negative pressure. Furthermore, when materials manufactured in factories are used as reinforcement, a certain production period may be required after receiving an order, or they may need to be stored indoors to ensure quality. However, due to their shape, logs 2 can be easily stacked and stored, which allows for good space-saving efficiency. They can also be stored outdoors, and no building is required for storage. This makes them suitable for stockpiling as a regular supply of lumber, allowing for materials to be delivered as needed, and materials to be supplied immediately when needed, such as in disaster response, and allowing for more flexible response to construction period conditions than conventional construction methods. Furthermore, in this embodiment, the ground, which contributes to the stability of the steel sheet piles 3, is reinforced with logs 2, so only space for heavy machinery to drive the logs 2 into the ground is required, which has the advantage of eliminating the need for a large-scale construction yard as in the case of ground improvement methods.

[0057] Furthermore, in this embodiment, the carbon dioxide absorbed from the atmosphere by the multiple logs 2 can be stored inside the ground, which has the advantage of contributing to CO2 reduction at construction sites and contributing to carbon neutrality.

[0058] In this embodiment, the logs 2 are driven into the soft ground G. In this way, in a condition where the soft ground G1 in the landward area R1 is blocked by the wall structure of the steel sheet piles 3 and the bracing members 4, directly driving the logs 2 into the soft ground G1 provides an improvement effect of increasing the restraining force due to compaction, and this also increases the resistance force of the bracing members 4.

[0059] In this embodiment, the logs 2 are installed by replacing a portion of the soft ground G. This configuration is a replacement construction method in which a portion of the soft ground G is pre-excavated and then the logs 2 are placed in the excavated holes, so the ground weight (density) in the improved area can be reduced. This reduces the active earth pressure acting on the steel sheet piles 3. Furthermore, by making the diameter of the excavation holes smaller than the diameter of the logs 2, it is possible to achieve both the effect of improving ground strength by spreading the ground and the effect of reducing the ground weight.

[0060] In this embodiment, the steel sheet piles 3 are made of steel. The amount of carbon dioxide stored in all of the logs 2 is greater than the amount of carbon dioxide emitted during the manufacturing of the revetment wall. With this configuration, the amount of carbon dioxide stored in all of the logs 2 is greater than the amount of carbon dioxide emitted during the manufacturing of the steel sheet piles 3, which leads to a reduction in the amount of CO2 in the atmosphere, and an environmentally friendly revetment structure 1 can be provided.

[0061] In this embodiment, the logs 2 are driven so as to apply a tensile force to the tie rods 5. With this configuration, the logs 2 can apply a tensile force to the tie rods 5, which increases the restraining force on the soft ground G1 in the landward region R1 between the steel sheet piles 3 and the supporting members 4, thereby more reliably achieving an improvement effect.

[0062] In this embodiment, at least one of the steel sheet piles 3, the bracing members 4, and the logs 2 is driven to a position deeper than the liquefaction layer. Therefore, by driving the lower ends of the steel sheet piles 3 and the logs 2 into stronger ground deeper than the liquefaction layer where liquefaction does not occur, the steel sheet piles 3 can have increased resistance to soil-water pressure acting from the liquefaction layer, and the logs 2 can have increased surrounding ground strength reliably throughout the entire thickness of the liquefaction layer, and can be kept in place without being displaced by the load from the liquefaction layer.

[0063] As described above, the revetment structure and construction method for the revetment structure according to this embodiment can easily and efficiently reinforce the entire revetment area to improve ground strength, simplify the structure, such as the embedded length of the steel sheet piles 3, and also contribute to reducing CO2 emissions at the construction site.

[0064] Next, other embodiments and modifications of the revetment structure and construction method for the revetment structure of the present invention will be described based on the attached drawings. Components and parts that are the same as or similar to those in the first embodiment described above will be designated by the same reference numerals, and their explanation will be omitted. Only configurations that differ from the first embodiment will be described.

[0065] (Second embodiment) 8 to 10, the revetment structures 1A, 1B, and 1C according to the second embodiment are configured such that the lower ends 2b of the logs 2 are located at a position deeper than at least one of a first passive collapse line K1 drawn from the lower ends 3b of the steel sheet piles 3 toward the soft ground G1 in the land-side region R1 at a passive collapse angle and a second passive collapse line K2 drawn from the lower ends 3b of the steel sheet piles 3 toward the soft ground G2 in the water-side region R2 at a passive collapse angle. In other words, the logs 2 are driven to a depth at which they intersect with at least one of the passive collapse lines K1 and K2 extending from the lower ends 3b of the steel sheet piles 3.

[0066] In the revetment structure 1A shown in Fig. 8, the lower ends 2b of the plurality of logs 2 in the land-side region R1 are located deeper than the first passive collapse line K1, and the lower ends 2b of the plurality of logs 2 in the water-side region R2 are located deeper than the second passive collapse line K2. Note that in Fig. 8, the lower ends 2b of all the logs 2 are deeper than the passive collapse lines K1 and K2, but it is also possible that only some of the logs 2 are deeper than the passive collapse lines K1 and K2.

[0067] In the revetment structure 1B shown in Figure 9, the lower ends 2b of multiple logs 2 in the landside region R1 are located deeper than the first passive collapse line K1. Although the lower ends 2b of all logs 2 in the landside region R1 are located deeper than the first passive collapse line K1 in Figure 9, only some of the logs 2 may be located deeper than the first passive collapse line K1. This can further reduce the earth pressure acting on the steel sheet pile 3 from the back ground (here, the landside region R1).

[0068] In the revetment structure 1C shown in Fig. 10, the lower ends 2b of the multiple logs 2 in the water area side region R2 are located deeper than the second passive collapse line K2. Note that, although the lower ends 2b of all the logs 2 in the water area side region R2 are deeper than the second passive collapse line K2 in Fig. 10, only some of the logs 2 may be deeper than the second passive collapse line K2.

[0069] In addition, in the revetment structure 1C, the log 2 closest to the steel sheet pile 3 among the logs 2 on the soft ground G2 on the water side is installed deeper than the lower end 3b of the steel sheet pile 3. This makes it possible to further increase the shear rigidity and shear resistance of the ground portion deeper than the bottom end of the steel sheet pile, thereby increasing the bearing capacity received from the ground near the bottom end of the steel sheet pile.

[0070] In the second embodiment, the length of some of the logs 2 to be placed can be shortened compared to when all logs 2 are set to the same length in each region R1, R2 as in the first embodiment described above.

[0071] In addition, in the second embodiment, since the log 2 crosses at least one of the first passive collapse line K1 and the second passive collapse line K2, the shear resistance of the log 2, which is larger than the ground, is added, thereby increasing the overall shear resistance of at least one of the first passive collapse line K1 and the second passive collapse line K2.In addition to the effect of increasing ground strength due to the increase in density of the surrounding ground caused by the installation of the log, the ground strength that efficiently supports the steel sheet pile 3 can be improved.

[0072] (Third embodiment) As shown in Fig. 11, the revetment structure 1D according to the third embodiment has logs 2 installed only on the soft ground G1 in the land-side region R1. In other words, no logs 2 are installed in the water-side region R2. All of the logs 2 installed in the land-side region R1 have the same length, and the lower ends 2b of these logs 2 are located shallower than the lower ends 3b of the steel sheet piles 3 and the lower ends 4b of the support members 4.

[0073] (Second Modification) In the revetment structure 1E according to the second modification shown in Fig. 12, the lower ends 2b of the plurality of logs 2 in the land side region R1 are located deeper than the first passive collapse line K1. Note that, although the lower ends 2b of all the logs 2 in the land side region R1 are deeper than the first passive collapse line K1 in Fig. 12, only some of the logs 2 may be deeper than the first passive collapse line K1.

[0074] (Fourth embodiment) As shown in Fig. 13, the revetment structure 1F according to the fourth embodiment has logs 2 installed only on the soft ground G2 in the water area region R2. In other words, no logs 2 are installed in the land area R1. All of the logs 2 installed in the water area region R2 have the same length, and the lower ends 2b of these logs 2 are at approximately the same depth as the lower ends 3b of the steel sheet piles 3.

[0075] (Third Modification) In the revetment structure 1G according to the third modification shown in Fig. 14, the lower ends 2b of the plurality of logs 2 in the water area side region R2 are located at a position deeper than the second passive collapse line K2. Note that, although the lower ends 2b of all the logs 2 in the water area side region R2 are deeper than the second passive collapse line K2 in Fig. 14, only some of the logs 2 may be deeper than the second passive collapse line K2. In addition, in cases where it is necessary to increase the ground strength only in the relatively shallow ground surrounding the installation of the steel sheet pile, it is not necessary to lengthen the logs to match the length of the steel sheet pile, and it is preferable to select the log length appropriately to minimize costs depending on the installation location.

[0076] (Fifth embodiment) As shown in Fig. 15, in the revetment structure 1H according to the fifth embodiment, the logs 2 are inclined so that they extend downward from the heads 4a of the support members 4 toward the steel sheet piles 3. The heads 2a of the inclined logs 2 are connected to the heads 4a of the support members 4. In this case, the connection structure is preferably a pin connection as shown in Fig. 3 above.

[0077] It should be noted that the head 2a of the inclined log 2 and the head 3a of the steel sheet pile 3 do not necessarily need to be connected, as long as there is a mechanism that allows compressive force to be transmitted from the head 3a of the steel sheet pile 3 to the log 2 that serves as the batter pile. For example, as shown in Figure 16, in order to suppress displacement of the log 2 toward the steel sheet pile 3 in the overall length direction, a structure such as an angle bar 23 may be attached to the head 3a of the steel sheet pile 3 so as to hold down the head of the log 2.

[0078] In the fifth embodiment, the head of at least one of the steel sheet pile 3 and the support member 4 is supported by an inclined log 2, and a compressive force is applied by tensioning the log 2 against loads that deform these heads, thereby suppressing deformation of the support member 4 on which the inclined log 2 is attached.

[0079] The above describes embodiments of the revetment structure and the construction method for the revetment structure according to the present invention, but the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the spirit of the present invention.

[0080] For example, in the above-described embodiment, steel sheet piles 3 are used as the revetment wall, but this is not limited to steel sheet piles, and other revetment wall structures, such as steel pipe sheet piles, can also be applied.

[0081] In addition, in this embodiment, tie rods 5 are used as connecting members, but this is not limiting. In short, any member that connects the revetment wall body and the bracing member may be used, and for example, a connecting member that integrally installs the revetment wall body and the bracing member using a concrete plate or the like.

[0082] In addition, it is possible to replace the components in the above-described embodiments with well-known components as appropriate, without departing from the spirit of the present invention. [Explanation of symbols]

[0083] 1. 1A~1H Revetment structure 2 logs 2a head 2b Bottom edge 3 Steel sheet piles (revetment walls) 4 Supporting members 5 Tie rod (connecting member) G, G1, G2 Soft ground K1 First passive collapse line K2 Second passive collapse line R1 Landside area (first area) R2 Water area (second area)

Claims

1. A revetment structure constructed by connecting a revetment wall body and a support member with a plurality of connecting members, A revetment structure in which a plurality of logs are provided in soft ground in at least one of a first region between the revetment wall and the supporting member and a second region on the water side of the revetment wall.

2. The revetment structure according to claim 1 , wherein the logs are driven into the soft ground.

3. The revetment structure according to claim 1 , wherein the logs are provided by replacing a portion of the soft ground.

4. The revetment structure according to claim 1 , wherein a lower end of at least one of the plurality of logs is deeper than a lower end of the revetment wall.

5. The revetment wall is formed of steel, The revetment structure according to claim 1 , wherein the amount of carbon dioxide stored in all of the plurality of logs is greater than the amount of carbon dioxide emitted during the manufacturing of the revetment wall.

6. The revetment structure according to claim 2 , wherein the plurality of logs are driven into the connecting member so that a tensile force is applied to the connecting member.

7. The revetment structure described in claim 1, wherein the lower end of the log is located at a position deeper than at least one of a first passive collapse line drawn from the lower end of the revetment wall at a passive collapse angle toward the soft ground in the first area and a second passive collapse line drawn from the lower end of the revetment wall at a passive collapse angle toward the soft ground in the second area.

8. The revetment structure according to claim 1 , wherein the logs are inclined so as to extend downward from a head of at least one of the revetment wall body and the bracing member toward the other.

9. The revetment structure according to claim 1 , wherein at least one of the revetment wall, the bracing members, and the logs is driven to a position deeper than the liquefaction layer.

10. a step of connecting the revetment wall body and the support members with a plurality of connecting members; a step of placing a plurality of logs on the soft ground in at least one of a first region between the revetment wall body and the supporting members and a second region on the water side of the revetment wall body; A construction method for a revetment structure, comprising:

11. The construction method for a revetment structure according to claim 10, wherein the logs are driven into the soft ground.

12. A step of pre-excavating the soft ground at the position where the log is to be placed and forming a pouring hole; A step of replacing the log by burying it in the driving hole; The construction method for a revetment structure according to claim 10, comprising:

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