Retaining wall, and foundation block

Abstract

To provide a retaining wall with a gentle slope of 10% or more.SOLUTION: There is provided a block-built retaining wall with a slope of at least 10%, which has a foundation block and a plurality of retaining wall blocks stacked on the foundation block. Each of the plurality of retaining wall blocks includes a front face portion and a bottom face portion arranged to form an acute angle. The foundation block includes a mounting portion on which the bottom face portion of the lowest retaining wall block of the plurality of retaining wall blocks is mounted in a tilted state backward at an angle θ, and the angle θ satisfies the following condition. 10 degrees≤θ<45 degrees.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to retaining walls and foundation blocks. [Background technology]

[0002] Patent Document 1 describes how, when constructing a gentle slope using slope blocks which have multiple polygonal columnar legs connected to the back of a block body which has a square front shape, and which have upper surfaces that are inclined relative to the sides of the block body, the slope blocks are stacked along the slope so that the sides of the block bodies are horizontal and so that the upper block bodies are offset by half the width from the lower block bodies, and after stacking, concrete is poured into the space between the slope and the back of the block bodies from above the slope, integrating the legs of the block bodies with the concrete.

[0003] Patent Document 2 describes slope protection blocks in which block bodies are arranged lengthwise and widthwise in a staggered pattern on the surface of a slope such as a road to protect the slope from erosion by sunlight, rainwater, etc., and positioning and installation work is carried out to improve work efficiency, and adjacent block bodies are integrally connected to prevent shifting and subsidence.

[0004] Patent Document 3 describes the provision of a retaining wall that can more easily construct retaining walls with different gradients of 3 / 4 / 5 / 8. Each of the multiple retaining wall blocks piled on the foundation block has a bottom surface that contacts the foundation or other retaining wall blocks below, a top surface that contacts other retaining wall blocks above, a front surface that serves as the surface of the retaining wall or its base, and a convex portion that partially protrudes downward from the bottom surface or upward from the top surface, and a first angle between the front surface and the bottom surface is an acute angle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-228394 [Patent Document 2] Japanese Patent Application Publication No. 9-3909 [Patent Document 3] JP 2019-127718 A Summary of the Invention [Problem to be solved by the invention]

[0006] Retaining walls for rivers and roads, especially for the banks of large rivers such as first and second class rivers, are constructed with gentle slope gradients of 10% (45 degrees) or 15% (1.5%, about 33.7 degrees) to enhance stability. When constructing such gently sloping retaining walls with block masonry, staking blocks and gap blocks as shown in Patent Document 1 have been widely adopted. In recent years, due to a decrease in the number of craftsmen who can construct the conventional staking blocks and gap blocks, retaining walls of the type shown in Patent Document 2, in which large, entirely rectangular or box-shaped retaining wall blocks are piled on foundation blocks and can be constructed by general civil engineering workers, are widely adopted.

[0007] FIG. 29 shows an example of a retaining wall 90 constructed by stacking large rectangular parallelepiped retaining wall blocks 93 on foundation blocks 91. FIG. 29(a) shows an example of a retaining wall 90 with a gradient (slope gradient) of 10% (45 degrees), and the mounting surface 91a of the foundation block 91 on which the retaining wall blocks 93 are mounted is inclined 45 degrees backward in accordance with the gradient. FIG. 29(b) shows an example of a retaining wall 90 with a gradient of 10.5% (1.5%, 33.7 degrees), and the mounting surface 91a of the foundation block 91 on which the retaining wall blocks 93 are mounted is inclined 56.3 degrees backward in accordance with the gradient. The front surface (foundation front surface) 91b of the foundation block 91 may be inclined backward at the same angle as the slope gradient or at a different angle. In particular, foundation blocks for large rivers are often used in large sizes with a gradient on the front surface, unlike foundation blocks used for retaining walls of roads and small and medium-sized rivers.

[0008] One of the challenges in constructing such gently sloping retaining walls is that the angle (slope) of the boundary between the foundation block and the retaining wall block, and the boundary between the retaining wall blocks themselves, is 45 degrees or greater (the angle becomes steeper), making the surfaces that meet at these boundaries, i.e., the mounting surface of the foundation block and the bottom surface of the retaining wall block, and the top and bottom surfaces of the retaining wall blocks, slip easily. These surfaces often have projections and recesses that allow them to engage with each other, and are often designed to interlock and prevent slipping.

[0009] For example, in the example shown in FIG. 29, the mounting surface 91a is provided with a convex portion 92 inclined at 45 degrees with respect to the mounting surface 91a. When the mounting surface 91a is inclined at 45 degrees or more, the convex portion 92 is directed downward from the nearly horizontal, and the weight of the retaining wall block 93 hardly has any effect of engaging with the block. The same is true when a convex portion 94 is provided on the upper surface of the retaining wall block 93. The angle of the convex or concave portion provided on the mounting surface may be steep, but the steeper the mounting surface angle, the lower the ability to engage. On the other hand, if the angle of the concave or convex portion is steep, the greater the possibility of chipping or of becoming an obstacle when prefabricating with a formwork. Furthermore, when the mounting surface is inclined at 45 degrees or more, the frictional force between the surfaces that come into contact at the boundary is further reduced. Therefore, skilled craftsmen are needed to stack the retaining wall blocks in a predetermined position relative to the foundation block, or to stack the retaining wall blocks on each other, which is a factor in the time it takes to construct a retaining wall with a gentle slope. [Means for solving the problem]

[0010] One aspect of the present invention is a block-built retaining wall with a gradient of at least 10% (45 degrees). This retaining wall has a foundation block and a plurality of retaining-wall blocks stacked on the foundation block, each of the plurality of retaining-wall blocks having a front surface and a bottom surface that are arranged to form an acute angle, and the foundation block includes a mounting portion on which the bottom surface of the lowest retaining-wall block of the plurality of retaining-wall blocks is mounted in a state in which it is tilted backward at an angle θ, and the angle θ satisfies the following condition (1). 10 degrees≦θ<45 degrees...(1) The lower limit of condition (1) may be 15 degrees or 18 degrees, and the upper limit may be 40 degrees.

[0011] An example of a retaining wall block in which the front part and the bottom part form an acute angle is a retaining wall block that has recently become widely used when constructing a steeply sloping and low-height retaining wall, for example, 5m or less, for small and medium-sized rivers and roads. Most of such retaining walls have a 5-minute slope, but it may also have a 3-minute or 4-minute slope. A 5-minute slope retaining wall block is manufactured so that the front part and the bottom part intersect at about 63.4 degrees at the front side of the retaining wall block. A 4-minute slope retaining wall block is manufactured so that the front part and the bottom part intersect at about 68.2 degrees, and a 3-minute slope retaining wall block is manufactured so that the front part and the bottom part intersect at about 73.3 degrees. The inventors of the present application have found that by using a retaining wall block manufactured for constructing such a steeply sloping retaining wall in the construction of a gentler retaining wall with a slope of 10% or more, the inclination of the mounting part (mounting surface) of the foundation block can be made less than 45 degrees, or even less than 40 degrees. For example, when constructing a retaining wall with a 10% gradient using a 5% gradient retaining wall block, the inclination of the mounting part of the foundation block can be suppressed to about 18.4 degrees, and when constructing a retaining wall with a 10% gradient, the inclination of the mounting part of the foundation block can be suppressed to about 29.7 degrees. Even when constructing a retaining wall with a 20% gradient, the inclination of the mounting part of the foundation block can be suppressed to about 36.9 degrees. This ensures friction between the mounting part of the foundation block and the bottom part of the retaining wall block (boundary), making it possible to realize a state where the foundation block is not easily slippery during construction. In addition, if the mounting part has unevenness to prevent or suppress slipping, even when constructing a retaining wall with a gentle gradient of 10% or more, the unevenness will be raised from the horizontal direction, making it easier for the mounting part and the bottom part to engage with each other, and making it possible to realize a state where the mounting part and the bottom part are not easily slippery during construction. As a result, when constructing a retaining wall with a relatively gentle slope of 10% or more, it becomes easy to stack the retaining wall blocks in their designated positions in relation to the foundation blocks, or to stack the retaining wall blocks on top of each other, reducing the labor required by construction workers and shortening the time required to construct the retaining wall.

[0012] The foundation block includes a contact area in the mounting portion that contacts at least the front and rear of the bottom surface of the retaining wall block at the lowest level. In a type of retaining wall in which the retaining wall blocks, whose front surface and bottom surface meet at an acute angle, are piled up at a gentle slope, the front-rear width of the contact area is longer than the front-rear thickness of the bottom retaining wall block. Therefore, the cross section of the foundation block is large, the foundation bottom surface tends to expand, and the area of ​​the foundation bottom surface that contacts the ground is wider than that of conventional foundation blocks. For this reason, the foundation block may include a foundation rear surface portion at least part of which is inclined backward, and the weight can be reduced by reducing the cross section of the foundation block while ensuring a predetermined strength. The foundation block may include a foundation rear surface portion at least part of which is inclined backward non-parallel to the foundation front surface portion. The foundation block may include a foundation rear surface portion that rises from the rear of the foundation bottom surface portion and inclined backward during the rise. The foundation block may have a protrusion at the rear of the widened mounting portion that is adapted to abut against the rear surface of the lowest retaining wall block.

[0013] The foundation block may include, in the mounting portion, a portion that engages with at least a part of the bottom surface portion of the lowest retaining wall block. The engaging portion may include at least one of an uneven portion, a convex portion, and a concave portion. The foundation block may include, in the mounting portion, a first horizontal groove portion into which concrete flows through the lowest retaining wall block. The connection between the lowest retaining wall block and the foundation block can be strengthened. The lowest retaining wall block may have, in its bottom surface portion, a second horizontal groove portion that faces the first groove portion. The foundation block may include vertical groove portions extending in the vertical direction on both side surfaces. The foundation blocks can be connected to each other. The vertical groove portion may be inclined backward. The vertical groove portion may widen toward the bottom. The vertical groove portion may have a cross section at the lower portion wider than the cross section at the upper portion. The vertical groove portion of the foundation block can be connected to the horizontal groove portion, and concrete can be poured into the horizontal groove portion and the vertical groove portion through the lowest retaining wall block. The foundation block may include a foundation front surface that is at least partially tilted rearward.

[0014] The foundation block has a foundation front wall portion, a foundation rear wall portion, and a foundation upper portion that connects the upper sides of the foundation front wall portion, and is provided with a mounting portion. The foundation upper portion may include an upper surface portion provided in front of the mounting portion, and at least one injection hole penetrating at least a part of the upper surface portion for injecting concrete into a space between the foundation front wall portion and the foundation rear wall portion. By providing a space between the foundation front wall portion and the foundation rear wall portion, the weight of the foundation block can be reduced, and factory prefabrication, transportation, and assembly at the site can be facilitated. On the other hand, at the site, after the foundation block is installed, concrete can be injected into the space between the foundation front wall portion and the foundation rear wall portion through the injection hole, and the foundation block can be stabilized. The upper opening of at least one injection hole may reach at least a part of the mounting portion. Concrete can be injected into the space between the foundation front wall portion and the foundation rear wall portion through the retaining wall blocks stacked on the foundation block, and the connection strength between the foundation block and the retaining wall block can be improved. At least one injection hole may be a tapered hole in which the width of the upper opening in the front-rear direction is wider than the width of the lower opening in the front-rear direction. The upper opening for injection can be made larger, while the provision of the opening can reduce cross-sectional loss, thereby providing a foundation block with high strength. A plurality of injection holes may be provided in the longitudinal direction (lateral direction, horizontal direction) of the upper surface. In particular, a foundation block having a horizontal length of 1 m or more, for example, a horizontal length of 1.5 m or 2 m or more, may have a plurality of injection holes. A haunch or arch portion capable of improving strength may be provided at the connection portion between the front wall portion of the foundation, the rear wall portion of the foundation, and the upper portion of the foundation.

[0015] The retaining wall of the present invention may further include a plurality of partition blocks stacked on the foundation block at a predetermined interval on the left and right of the plurality of retaining wall blocks. Each of the plurality of partition blocks includes a rear surface portion and a bottom surface portion arranged at a right angle, and the bottom surface portion of the partition block at the bottom of the plurality of partition blocks includes a step or notch that engages with at least a part of the mounting portion of the foundation block and at least a part of the foundation rear surface portion behind the mounting portion. By providing a step or notch in the bottommost stage, partition walls for stably stacking the retaining wall blocks can be constructed at a predetermined interval using conventional rectangular partition block.

[0016] Each of the plurality of retaining wall blocks used in the retaining wall of the present invention may be a retaining wall block for forming a retaining wall with a gradient of 3%, 4%, or 5% when the bottom surface portions are stacked horizontally. The block-built retaining wall may have a gradient of 10.5%, and each of the plurality of retaining wall blocks may be a retaining wall block for forming a retaining wall with a gradient of 10% when the bottom surface portions are stacked horizontally.

[0017] Another aspect of the present invention is the foundation block described above. The foundation block is for building a retaining wall by stacking retaining wall blocks, the front surface of which is provided so that it forms an acute angle with the bottom surface of the retaining wall block, and has a mounting portion on which the bottom surface of the retaining wall block is mounted in a state inclined backward, and the mounting portion includes a contact area that contacts the bottom surface of the retaining wall block at least in the front and rear, and the contact area is longer in the front and rear direction than the thickness of the retaining wall block in the front and rear direction. The foundation block may have a foundation rear surface portion at least a part of which is inclined backward. The foundation block may have a foundation front surface portion and a foundation upper surface portion provided between the foundation front surface portion and the mounting portion. In addition to or in addition to the various features described above, the foundation block may have one or more grooves provided at a position where the mounting portion contacts the retaining wall block. The multiple grooves may include grooves extending in the front-to-back direction, which are grooves for attaching gaskets that adjust the height of the retaining wall blocks when stacked.The foundation block may further have a groove extending in the front-to-back direction, which is provided at a position where the mounting part contacts the retaining wall block, and is for inserting a jig that adjusts the position of the retaining wall blocks when stacked.

[0018] Yet another aspect of the present invention is a method for constructing a block-built retaining wall with a gradient of at least 10%. The method includes stacking a plurality of retaining wall blocks on a foundation block, each of the plurality of retaining wall blocks having a front surface and a bottom surface that are provided to form an acute angle, and stacking includes mounting a bottom surface of a lowermost retaining wall block of the plurality of retaining wall blocks on the foundation block in a state in which the bottom surface is tilted backward at an angle θ, and the angle θ satisfies the above condition (1). The foundation block may include a first horizontal groove portion in the mounting portion, and the method may further include pouring concrete into the first horizontal groove portion through the lowermost retaining wall block. The foundation block may include a front foundation wall portion, a rear foundation wall portion, and an upper foundation portion that connects the upper sides of the front foundation wall portion, the rear foundation wall portion, and the upper foundation portion on which the mounting portion is provided, and the upper foundation portion may include an upper surface portion provided in front of the mounting portion, and at least one injection hole that penetrates at least a part of the upper surface portion and reaches a space between the front foundation wall portion and the rear foundation wall portion. The method may further include pouring concrete into a space between the front foundation wall and the rear foundation wall through the at least one pouring hole.

[0019] Each of the multiple retaining wall blocks used in the construction may be a retaining wall block for forming a retaining wall with a gradient of 3%, 4%, or 5% when the bottom surface portion is stacked horizontally. Also, if the block-built retaining wall has a gradient of 10.5%, each of the multiple retaining wall blocks may be a retaining wall block for forming a retaining wall with a gradient of 10% when the bottom surface portion is stacked horizontally.

[0020] The method may further include stacking a plurality of partition blocks on the foundation block at a predetermined interval to the left and right of the plurality of retaining wall blocks. Each of the plurality of partition blocks includes a rear surface portion and a bottom surface portion disposed at a right angle, and the bottom surface portion of the lowest partition block of the plurality of partition blocks may include a step or notch that engages with at least a portion of the mounting portion of the foundation block and at least a portion of the foundation rear surface portion rearward of the mounting portion. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram showing an overview of the retaining wall of the present invention. [Diagram 2] A diagram showing some examples of retaining wall blocks. [Diagram 3] A diagram showing the state in which retaining wall blocks are stacked on the foundation block of the retaining wall of the present invention. [Figure 4] FIG. 2 is a diagram showing a comparison between the foundation block of the retaining wall of the present invention and the foundation block of a conventional retaining wall. [Diagram 5] FIG. 1 shows an example of a foundation block. [Figure 6] 11A to 11C are diagrams showing different examples of foundation blocks. [Figure 7] A figure showing yet another example of a foundation block. [Figure 8] A figure showing yet another example of a foundation block. [Figure 9] A diagram showing an overview of constructing a retaining wall using foundation blocks. [Figure 10] A figure showing yet another example of a foundation block. [Figure 11] A figure showing yet another example of a foundation block. [Figure 12] A figure showing yet another example of a foundation block. [Figure 13] A figure showing yet another example of a foundation block. [Figure 14] FIG. 14 is a diagram showing details of the foundation block shown in FIG. 13. [Figure 15] FIG. 14 is a diagram showing an overview of the construction of a retaining wall using the foundation blocks shown in FIG. 13. [Figure 16] A figure showing yet another example of a foundation block. [Figure 17] A figure showing yet another example of a foundation block. [Figure 18] FIG. 18 is a diagram showing details of the foundation block shown in FIG. 17. [Figure 19] FIG. 18 is a diagram showing an overview of the construction of a retaining wall using the foundation blocks shown in FIG. 17. [Figure 20] A figure showing yet another example of a foundation block. [Figure 21] A figure showing yet another example of a foundation block. [Figure 22]A figure showing yet another example of a foundation block. [Diagram 23] FIG. 2 is a diagram showing an overview of constructing a partition wall using partition wall blocks. [Figure 24] FIG. 4 is a diagram showing details of a partition block. [Diagram 25] 11A and 11B are diagrams showing different examples of partition wall blocks. [Figure 26] A figure showing yet another example of a foundation block. [Figure 27] 13 is a perspective view showing yet another example of a foundation block. FIG. [Figure 28] A diagram showing an overview of constructing a retaining wall using the foundation blocks shown in Figure 27. [Figure 29] FIG. 1 is a diagram showing an example of a conventional retaining wall. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] FIG. 1 shows an example of a retaining wall 1 with a gradient of 10.5% (approximately 35.7 degrees) as an example of a block masonry retaining wall with a gradient of at least 10%. This retaining wall 1 has a foundation block 20 and a plurality of retaining wall blocks 10 stacked on the foundation block, and is constructed to reinforce a slope 5 of a river, road, etc. For example, the retaining wall 1 is constructed by installing the foundation block 20 and the retaining wall blocks 10 via crushed stones 6 on a slope 5 formed with a predetermined gradient, and fixing the blocks in place by pouring in mortar or concrete. Each of the plurality of retaining wall blocks 10 stacked on the foundation block 20 includes a front portion 11 and a bottom portion 13 that are provided to form an acute angle β, and the foundation block 20 includes a mounting portion 22 on which the bottom portion 13 of the lowest retaining wall block 10 of the plurality of retaining wall blocks 10 is mounted in a state inclined backward at an angle θ. In the retaining wall 1 of the present invention, even if the gradient is a gentle gradient of 10% (45 degrees) or more, construction is performed so that the rearward inclination (angle θ) of the mounting portion 22 of the foundation block 20 is 45 degrees or less.

[0023] FIG. 2 shows some examples of retaining wall blocks 10 in which the front portion 11 and the bottom portion 13 intersect at an acute angle β. The retaining wall block 10 in which the front portion 11 and the bottom portion 13 intersect at an acute angle β is a large concrete stacking block developed for constructing a retaining wall with a steep slope of 3 minutes, 4 minutes, or 5 minutes and a height of about several meters, for example, 5 m or less, as disclosed in JP 2019-127718 A (Patent Document 3). One example of the retaining wall block 10 has a rectangular front portion (front wall) 11 and a rear portion (rear wall) 12 with a vertical width of about 670 mm and a horizontal length of about 1500 mm, and has a side shape in which they are combined by a connecting wall 14 to form a parallelogram shape inclined at 5 minutes (about 63.4 degrees) with a distance (thickness, distance from outer surface to outer surface) B of about 350 mm. Therefore, the bottom surface portion 13 is formed by combining the lower end (bottom surface) 11a of the front surface portion (front wall) 11 and the lower end (bottom surface) 12a of the rear surface portion (rear wall) 12, and the distance in the front-to-rear direction of the bottom surface portion 13 (width, width in contact with the bottom, space between them) is the horizontal width A (dimension A) between the front surface portion 11 and the rear surface portion 12, which is approximately 391 mm. Also, the upper end (top surface) 11b of the front surface portion (front wall) 11 and the upper end (top surface) 12b of the rear surface portion (rear wall) 12 form the upper surface portion (top surface, top) 16, on which the next retaining wall block 10 is stacked.

[0024] In addition, even in the case of such retaining wall blocks 10 having a parallelogram cross section, as with conventional rectangular retaining wall blocks, the distance between the front portion 11 and the rear portion 12 (dimension B shown in Figure 2(c)), which becomes the thickness of the retaining wall 1 to be constructed (the thickness perpendicular to the slope), is often used as the standard or name of the retaining wall block 10.

[0025] This retaining wall block 10 has a rectangular front view with a height of about 600 mm and a width of 1500 mm, and the front part 11 may have various decorations 11f such as natural stone or tiles in front of it. The retaining wall block 10 may have projections and recesses to engage with the foundation block 20 or other retaining wall blocks 10 when stacked, and the retaining wall block 10 of this example has a projection 15 that protrudes downward from the lower side of the connecting wall 14, and when the bottom part 13 of the retaining wall block 10 is placed on the mounting part 220 of the foundation block 200, the projection 15 is combined with and engaged with the recess 230 of the foundation block. In addition, when the bottom surface 13 of the next (upper) tier of retaining wall block 10 is mounted on the upper surface 16 of the lowest tier of retaining wall block 10, the convex portion 15 enters into the space (recess) formed between the upper end 11b of the front wall 11 and the upper end 12b of the rear wall 12 that constitute the upper surface 16, so that the upper and lower retaining wall blocks 10 engage with each other.

[0026] As shown in Fig. 2, the angle β of the lower front corner where the front wall portion 11 and the bottom surface portion 13 intersect is an acute angle, and by mounting it on a foundation block 200 equipped with a horizontal mounting portion 220, it is possible to construct a 3-, 4-, or 5-minute retaining wall 99. As shown in Fig. 2(a), the angle β of the retaining wall block 10 for constructing a retaining wall 99 with a 3-minute slope is about 73.3 degrees, as shown in Fig. 2(b), the angle β of the retaining wall block 10 for constructing a retaining wall 99 with a 4-minute slope is about 68.2 degrees, and as shown in Fig. 2(c), the angle β of the retaining wall block 10 for constructing a retaining wall 99 with a 5-minute slope is about 63.4 degrees. In the following, we will explain an example of constructing a retaining wall 1 with a gentle slope of 10% or more using retaining wall blocks 10 for constructing a retaining wall 99 with a steep slope of 5 minutes, but it is also possible to construct a retaining wall 1 with a similar gentle slope using retaining wall blocks 10 for constructing a retaining wall 99 with a slope of 3 minutes or 4 minutes.

[0027] FIG. 3 shows an enlarged example of a foundation block 20 for a retaining wall 1 with a gentle slope shown in FIG. 1. FIG. 3(a) shows a foundation block 20 for a retaining wall 1 with a slope of 10%, and FIG. 3(b) shows a foundation block 20 for a retaining wall 1 with a slope of 1.5%. The foundation block 20 includes a mounting portion 22 on which the bottom portion 13 of the retaining wall block 10 is mounted in a state inclined backward (toward the slope) at an angle θ, and a rear portion (foundation rear portion, foundation rear portion) 23 rising from the rear 25a of the bottom portion (foundation bottom portion) 25 of the foundation block 20 toward the mounting portion 22. The foundation rear portion 23 of the foundation block 20 in this example has a shape in which the lower portion 23b rises almost vertically from the bottom portion 25, and the upper portion 23a is inclined backward (the upper end is shifted backward).

[0028] That is, the foundation block 20 of this example is a concrete block with a cross section of a nearly pentagon extending horizontally, and includes a front part (foundation front, foundation front part) 21 inclined backward (toward the slope 5), an upper part (foundation upper surface, foundation upper surface part) 26 extending almost horizontally, a mounting part (mounting surface) 22 inclined backward (inclined so that the rear is lower than the front), a rear part (foundation rear surface, foundation rear surface part) 23 extending downward from the rear end of the mounting part 22, and a bottom part (foundation bottom surface part, foundation surface) 25 in contact with the ground or basing concrete. The mounting part 22 is V-shaped in the center and has a groove-like shape extending horizontally (laterally), and the mounting part 22 inclined backward at an angle θ is formed by both ends 22a and 22b above (upper and lower) the recess (lateral groove part, first lateral groove part) 24. Mortar can be injected into this horizontal groove 24 through the internal space of the retaining wall block 10 stacked on the foundation block 20, thereby strengthening the bond between the foundation block 20 and the retaining wall block 10.

[0029] In order to align and connect (install) horizontally arranged foundation blocks 20 in the front-to-rear direction, depressions (recesses, vertical grooves) 28 into which mortar can be injected are provided in the side surfaces (both side surfaces) 27 of the foundation block 20, extending vertically. In the foundation block 20 of this example, the horizontal grooves (horizontal grooves) 24 extend in the longitudinal direction of the foundation block 20 to reach both side surfaces 27, and the vertical grooves (vertical grooves) 28 are connected to the horizontal grooves 24 and extend diagonally backward in the vertical direction (inclined so that the upper part of the groove is rearward relative to the lower part). Therefore, the foundation block 20 has a structure that allows mortar to be injected into the vertical grooves 28 via the horizontal grooves 24.

[0030] The vertical grooves 28 may widen downward. That is, the cross section (opening, cross-sectional area, opening area) of the lower part of the vertical grooves 28 may be wider than the cross section (opening, cross-sectional area, opening area) of the upper part. The concrete or mortar poured into the vertical grooves 28 can suppress the vertical movement of the foundation blocks 20 that are constructed side by side in the horizontal direction. The vertical grooves 28 reach the bottom surface portion 13, and the concrete or mortar poured into the vertical grooves 28 becomes one with the foundation concrete on which the foundation blocks 20 are installed, suppressing the phenomenon of the foundation blocks 20 moving or shifting.

[0031] In the present invention, by using retaining wall blocks 10 in which the angle β of the front lower corner where the front wall portion 11 and bottom portion 13 intersect is an acute angle, it is possible to construct a retaining wall 1 with an angle θ of the mounting portion 22 of 45 degrees or less and a gentle slope of 10% (45 degrees) or more. For this reason, the slope θ of the mounting portion 22 of the foundation block 20 only needs to satisfy the following condition (1). The lower limit of condition (1) may be even lower. It is also possible to construct a retaining wall with an even gentler slope by using retaining wall blocks with an adjusted angle β specifically for a gentle slope retaining wall.

[0032] On the other hand, for example, the inclination θ of the mounting portion 22 of the foundation block 20 for constructing (constructing) a retaining wall 1 with a gradient of 10% (45°) using a retaining wall block 10 with an acute angle β of 5 minutes (approximately 63.4°) is approximately 18.4°. The inclination θ of the mounting portion 22 of the foundation block 20 for constructing a retaining wall 1 with a gradient of 10% (1.5%, approximately 35.7°) using this retaining wall block 10 is approximately 29.7°. The inclination θ of the mounting portion 22 of the foundation block 20 for constructing a retaining wall 1 with a gradient of 20% (approximately 26.6°) is approximately 36.9°, and the inclination θ of the mounting portion 22 of the foundation block 20 for constructing a retaining wall 1 with a gradient of 20% (2.5%, approximately 21.8°) is approximately 41.6°. Therefore, by using foundation blocks 20 that satisfy condition (2) for the angle θ of mounting portion 22 to be 45 degrees or less, a retaining wall 1 with a gentle gradient of 10% to 2.5% can be constructed. Also, by using foundation blocks 20 that satisfy condition (3) for the angle θ of mounting portion 22 to be 40 degrees or less, a retaining wall 1 with a gentle gradient of 10% to 20% can be constructed. 10 degrees≦θ<45 degrees...(1) 15 degrees≦θ<45 degrees...(2) 18 degrees≦θ≦40 degrees...(3)

[0033] The inclination θ of the mounting portion 22 of the foundation block 20 for constructing a retaining wall 1 with a gradient of 10% (45°) using a retaining wall block 10 with an acute angle β of 4 minutes (approximately 68.2°) is approximately 23.2°, the inclination θ of the mounting portion 22 of the foundation block 20 for constructing a retaining wall 1 with a gradient of 10% and 50% (approximately 35.7°) is approximately 32.5°, and the inclination θ of the mounting portion 22 of the foundation block 20 for constructing a retaining wall 1 with a gradient of 20% (approximately 26.6°) is approximately 41.6°. Therefore, a retaining wall 1 with a gentle gradient of 10% to 20% can be constructed using a foundation block 20 in the range of condition (2). Also, a retaining wall 1 with a gentle gradient of 10% to 18% can be constructed using a foundation block 20 in the range of condition (3).

[0034] To construct a retaining wall 1 with a gradient of 10% (45 degrees) using retaining wall blocks 10 with an acute angle β of 3 minutes (approximately 73.3 degrees), the inclination θ of the mounting portion 22 of the foundation block 20 is approximately 28.3 degrees, and to construct a retaining wall 1 with a gradient of 15% (approximately 35.7 degrees), the inclination θ of the mounting portion 22 of the foundation block 20 is approximately 37.6 degrees. Therefore, a retaining wall 1 with a gentle gradient of about 10% to 18% can be constructed using foundation blocks 20 in the range of condition (2). Also, a retaining wall 1 with a gentle gradient of about 10% to 15% can be constructed using foundation blocks 20 in the range of condition (3).

[0035] The retaining wall 1 is constructed (constructed) by stacking (mounting) a number of retaining-wall blocks 10 on a foundation block 20. For this reason, the boundary between the stacked retaining-wall blocks 10, i.e., the gradient α of the top surface 16 of the lower retaining-wall block 10, can also be controlled in the same way. For example, by setting the gradient of the mounting portion 22 of the foundation block 20 to the above conditions (2) and (3), respectively, the gradient α of the boundary portion (top surface 16 and bottom surface 13) of the retaining-wall blocks 10 of the retaining wall 1 with a gentle gradient of 10% or more can be set to the following conditions (4) and (5). 15 degrees≦α<45 degrees...(4) 18 degrees≦α≦40 degrees...(5)

[0036] FIG. 4 shows a comparison between the retaining wall 1 according to the present invention and a retaining wall 90 according to the conventional construction method shown in FIG. 29. FIG. 4(a) shows the retaining walls 1 and 90 with a gradient of 10%, and FIG. 4(b) shows the retaining walls 1 and 90 with a gradient of 10.5%. The retaining wall 90 constructed using a conventional block 93 for a retaining wall, which is a rectangular parallelepiped with a rectangular side view and has a front surface 93a and a bottom surface 93b that are orthogonal (90 degrees), is shown by a broken line, and the retaining wall 1 constructed using a block 10 for a retaining wall, which is a parallelogram with a front surface 11 and a bottom surface 13 that are arranged to intersect at an acute angle β (5 degrees in this example) is shown by a solid line. As shown by the broken line, when the conventional block 93 for a retaining wall is used, the inclination of the mounting surface 91a of the foundation block 91 for constructing a retaining wall 90 with a gentle gradient of more than 10% is 45 degrees or more. Therefore, the angle of the engagement protrusion 92 provided on the mounting surface 91a changes to horizontal or downward, making it difficult to ensure that the foundation block 91 and the retaining wall block 93, or the retaining wall blocks 93 engage with each other. If the convex portion 92 protrudes at, for example, 45 degrees, the inclination of the convex portion 92 becomes horizontal at a gradient of 10%, and the convex portion 92 protrudes downward at a gradient of more than 10%. The same applies if a concave portion is provided instead of a convex portion as an engagement configuration. Furthermore, when the inclination is 45 degrees or more, the friction force between the retaining wall block 93 and the mounting surface 91a also decreases. Therefore, even if the foundation block 91 and the retaining wall block 93, or the retaining wall blocks 93 are stacked on top of each other at the site, they tend to fall, and it is not easy to maintain the stacked state.

[0037] On the other hand, the inclination θ of the mounting portion (mounting surface) 22 of the foundation block 20, which is used to build a gently sloping retaining wall 1 by stacking the retaining wall blocks 10, which are parallelograms in side view and have a front portion 11 and a bottom portion 13 that intersect at an acute angle β, is less than 45 degrees, or even less than 40 degrees. Therefore, if a convex portion 29 is provided on the mounting surface 22 as an engagement structure, the convex portion 29 will be maintained in an upwardly rising state without becoming horizontal. Therefore, the convex portion 29 of the mounting surface 22 will engage with the concave portion 19 provided on the bottom portion 13 of the retaining wall block 10, making it difficult for the retaining wall block 10 to slip relative to the foundation block 20, and it will be easy to maintain the retaining wall blocks 10 stacked on the foundation block 20 using a jig or the like.

[0038] Furthermore, the length (width) A in the front-to-rear direction where the retaining wall block 10, which is a parallelogram in side view and has the front surface 11 and bottom surface 13 intersecting at an acute angle β, contacts the mounting portion 22 of the foundation block 20 is larger (longer) than the thickness (distance between the front wall portion 11 and the rear wall portion 12) B of the retaining wall block 10. For this reason, the width (length, width) A of the area (contact area) 22c where the mounting portion 22 of the foundation block 20 contacts the bottom surface 13 of the retaining wall block 10 is larger than the width (thickness) B where the conventional foundation block 91 contacts the retaining wall block 93. For example, in a 5-minute retaining wall block 10, the width A in the front-to-rear direction of the bottom surface 13 is approximately 12% larger than the thickness B. Therefore, by combining retaining wall blocks 10 whose front surface 11 and bottom surface 13 intersect at an acute angle β with foundation blocks 20 whose mounting portions 22 have a small inclination angle θ to construct a gently sloping retaining wall 1, the contact area between the retaining wall blocks 10 and the foundation blocks 20 can be increased, making it easier to ensure friction. For this reason, when stacking the retaining wall blocks 10 on the foundation blocks 20, the retaining wall blocks 10 are less likely to slip against the foundation blocks 20, allowing the retaining wall 1 to be constructed more stably.

[0039] Furthermore, the width A of the contact area 22c included in the mounting portion 22 that contacts the retaining wall block 10 becomes larger than the thickness B of the retaining wall block 10, and the width of the mounting portion 22 also becomes larger. This results in a larger foundation block 20, and since the cross-sectional area can be secured, it is easy to ensure the strength of the foundation block 20. On the other hand, since the cross-sectional area becomes larger, the weight of the foundation block 20 increases, and the manufacturing cost tends to increase, and there is a possibility that weight reduction will be required to solve problems in transportation in factories and on-site and in construction on-site.

[0040] 5 to 7 show some examples of the foundation block 20. FIG. 5(a) shows the foundation block 20 for constructing the retaining wall 1 with a 10% gradient shown in FIG. 4(a), and FIG. 5(b) shows the foundation block 20 for constructing the retaining wall 1 with a 15% gradient shown in FIG. 4(b). As described above, compared to the conventional foundation block 91 shown by the dashed line, the angle θ of the mounting part 22 that contacts the retaining wall block 10 is gentler (smaller), while the mounting surface 22 is wider (longer) in width (front-to-back length) because it contacts the bottom surface part 13 of the retaining wall block 10. For this reason, the foundation block 20 becomes large in a design that ensures the top surface part 26 in the same manner as in the conventional one. The area of ​​the bottom surface (foundation bottom surface part) 25, which performs the main function as a foundation, is also larger, but the foundation area may be the same as that of the conventional foundation block 91 in terms of the design of the retaining wall. Therefore, the inventors of the present application have noted that the shaded portion 31 of the base block 20 shown in FIG. 5 is a portion that can be considered as redundant and can be deleted.

[0041] FIG. 6 shows examples of different foundation blocks 20. FIG. 6(a) shows a foundation block 20 for constructing a retaining wall 1 with a 10% gradient, and FIG. 6(b) shows a foundation block 20 for constructing a retaining wall 1 with a 15% gradient. These foundation blocks 20 include a rear surface portion (foundation rear surface, foundation rear surface portion) 23 that is inclined backward. That is, the foundation rear surface portion 23 connects the rear (rear end) 25a of the foundation bottom surface portion 25 and the rear (for example, the rear end of the contact area 22c) 22a of the mounting portion 22, and is configured so that the upper end 22a protrudes backward (toward the slope) relative to the lower end 25a. Therefore, in these foundation blocks 20, the area of ​​the foundation bottom surface portion 25 can be reduced to the same extent as that of the conventional foundation block 91 while ensuring the width A of the mounting portion 22. Therefore, the foundation block 20 for constructing a gently sloping retaining wall 1, in which the angle θ at which the mounting portion 22 is tilted backward is less than 45 degrees or 40 degrees or less, can be made lighter and supplied at low cost, and labor required at the site can be reduced. The front portion (foundation front portion) 21 of the foundation block 20 may be tilted backward, and the rear portion 23 may be tilted parallel to the front portion 21 or may be tilted non-parallel. In addition, the rear portion 23 may be tilted backward at a uniform angle as a whole, or may be partially tilted backward, or the tilt backward may vary between the upper and lower portions.

[0042] FIG. 7 shows another example of the foundation block 20. FIG. 7(a) shows a foundation block 20 for constructing a retaining wall 1 with a 10% gradient, and FIG. 7(b) shows a foundation block 20 for constructing a retaining wall 1 with a 10% gradient. These foundation blocks 20 include a rear surface portion (foundation rear surface portion) 23 rising from the rear surface 25a of the foundation bottom surface portion 25, and the rear surface portion 23 inclined backward during the rising. That is, the rear surface portion 23 of this foundation block 20 includes a rear surface portion lower portion 23b rising almost vertically from the bottom surface portion 25, and a rear surface portion upper portion 23a inclined backward. The rear surface portion 23 rising from the rear surface 25a of the foundation bottom surface portion 25 may have a different angle of backward inclination during the rising. In these foundation blocks 20, the area of ​​the foundation bottom surface portion 25 can be reduced to the same extent as that of the conventional foundation block 91 while ensuring the width A of the mounting portion 22. Therefore, the foundation block 20 for constructing a gently sloping retaining wall 1, in which the angle θ tilted toward the rear of the mounting part 22 is less than 45 degrees or 40 degrees or less, can be made lighter and supplied at low cost.

[0043] FIG. 8 shows the foundation block 20 described in FIG. 3. FIG. 8(a) is a perspective view from the rear (back direction), FIG. 8(b) is a right side view, FIG. 8(c) is a cc cross-sectional view perpendicular to the longitudinal direction, and FIG. 8(d) is a dd cross-sectional view parallel to the longitudinal direction. An example of the foundation block 20 is a factory-prefabricated concrete block (precast concrete block) with a longitudinal (horizontal) length of about 1495 mm, a front part 21 height of 700 mm, a rear part 23 height of 509 mm, and a front-to-rear width of the bottom part 25 of 670 mm. These dimensions are merely examples and are not limiting.

[0044] This foundation block 20 has a generally V-shaped recess (first horizontal groove) 24 in the center of the mounting portion 22, which engages with the protrusion 15 protruding downward from the bottom portion 13 of the retaining wall block 10 shown in Fig. 3, making the bottom portion 13 less slippery when the retaining wall blocks 10 are stacked. This foundation block 20 has a rear portion (back side) 23 in a V-shape or bow shape that is inclined backward (back side) to reduce the weight of the back side of the foundation block 20, and a V-shaped groove 24 is provided on the mounting surface 22 of the foundation block 20, further reducing the weight of the foundation block 20 and making it possible to provide it at low cost. In addition, a vertical groove (recess) 28 is provided in the center of both side surfaces 27, recessed in a V-shape and extending vertically. When a plurality of foundation blocks 20 are arranged horizontally (longitudinal direction) to form the foundation of the retaining wall 1, the grooves 28 between the sides of adjacent foundation blocks 20 are filled with mortar or the like to connect the foundation blocks 20 together, thereby constructing a strong foundation.

[0045] As shown in FIG. 9, the retaining wall block 10 is hollow, and during construction of the retaining wall 1, it is possible to pour concrete 7 into the horizontal groove 24 through the lowermost retaining wall block 10 mounted on the foundation block 20. The horizontal groove 24 extends to both side surfaces 27 in the horizontal direction (longitudinal direction, horizontal direction) and connects to vertical grooves 28 provided on both side surfaces 27. Therefore, during construction of the retaining wall 1, it is possible to pour concrete 7 into the vertical groove 28 through the horizontal groove 24. The opening portion of the bottom surface portion 13 of the retaining wall block 10 functions as a second horizontal groove facing (opposing) the first horizontal groove 24 of the foundation block 20, and by pouring concrete 7 between them, the retaining wall block 10 can be firmly connected to the foundation block 20 by the concrete (mortar) 7. Furthermore, the vertical grooves 28 of the foundation blocks 20 face the vertical grooves of the adjacent foundation blocks 20, and the foundation blocks 20 can be firmly connected to each other by pouring concrete 7 between them.

[0046] As shown in FIG. 8, the foundation block 20 includes two shallow grooves 38 and 39 extending in the front-rear direction at the upper and lower ends (contact surfaces, contact parts) 22b and 22a of the contact area 22c of the mounting part 22 that contacts the bottom surface part 13 of the retaining wall block 10. The depth of these grooves 38 and 39 may be several mm to about 1 cm, and one of the grooves 39 is a groove for inserting a jig such as a crowbar between the foundation block 20 and the retaining wall block 10 to fine-tune the front-rear and left-right positions when stacking the retaining wall block 10 on the foundation block 20 and to adjust the front-rear and left-right height variations. The other groove 38 is a groove for inserting a packing or the like between the foundation block 20 and the retaining wall block 10 to maintain the finely adjusted front-rear and left-right height. The left and right grooves 38 and 39 may be used for any purpose. The bottom surface part 13 of the retaining wall block 10 may have similar grooves at positions facing these grooves 38 and 39.

[0047] Fig. 10 shows a different example of the foundation block 20. This foundation block 20 has basically the same configuration as the foundation block 20 shown in Fig. 8, and includes a rear surface portion 23 in which a lower side 23b of the rear surface portion 23 extends vertically from a bottom surface portion 25 and an upper side 23a is inclined backward (toward the rear surface, toward the slope), and the rear surface portion 23 has an overall V-shaped or bow-shaped cross section. The side surface 27 may be flat as in this example, or may have a recess or groove, or may have a recess on one side surface and a protrusion on the other side surface, so that the side surfaces of the foundation blocks 20 arranged side by side mesh with each other.

[0048] FIG. 11 shows some examples of foundation blocks 20 in which the rear surface 23 is inclined backward (toward the rear surface) and has a bow shape. FIG. 11(a) shows a foundation block 20 having a substantially flat mounting portion (mounting surface) 22. The mounting surface 22 of the foundation block 20 may have a convex portion 32 extending in the longitudinal direction as shown in FIG. 11(b), a concave portion (groove) 33 extending in the longitudinal direction as shown in FIG. 11(c), discontinuous convex portions 32 may be provided at both ends as shown in FIG. 11(d), or a convex portion 32 may be provided in the center as shown in FIG. 11(e). Also, as shown in FIG. 11(d), the foundation block 20 has an opening 35 in the center, which may be used as an injection hole for injecting concrete during construction.

[0049] FIG. 12 shows some examples of the foundation block 20 in which the rear surface portion 23 is inclined almost uniformly backward (backward). FIG. 12(a) shows the foundation block 20 having a nearly flat mounting portion (mounting surface) 22. The mounting surface 22 of the foundation block 20 may have a convex portion 32 extending in the longitudinal direction as shown in FIG. 12(b), a concave portion (groove) 33 extending in the longitudinal direction as shown in FIG. 12(c), discontinuous convex portions 32 may be provided at both ends as shown in FIG. 12(d), or a concave portion 33 may be provided in the center as shown in FIG. 12(e). Also, as shown in FIG. 12(d), the foundation block 20 may have an opening 35 in the center.

[0050] 13 to 15 show further different examples of the foundation block 50. FIG. 13(a) is a perspective view of the foundation block 50, and FIG. 13(b) shows the state in which the bottom retaining wall block 10 is mounted on the foundation block 50. FIG. 14(a) is a plan view of the foundation block 50, FIG. 14(b) is a front view of the foundation block 50, FIG. 14(c) is a rear view of the foundation block 50, FIG. 14(d) is a bottom view of the foundation block 50, and FIG. 14(e) is a left side view of the foundation block 50. The right side view of the foundation block 50 is symmetrical to the left side view. FIG. 15 shows how the retaining wall blocks 10 are stacked to construct the retaining wall 1 using the cross section XV-XV of the foundation block 50.

[0051] An example of the size of the foundation block 50 is a relatively large foundation block 50 having a height of 1000 mm, a front-to-back width of 890 mm, and a left-to-right length of about 1500 mm. The size of the foundation block 50 is an example, and is not limited to this. The foundation block 50 is a foundation block including a foundation front wall portion (front wall) 51, a foundation rear wall portion (rear wall) 53, and a foundation upper portion (upper structure) 52 that connects the upper sides of these and has a mounting portion 22 provided thereon, and the lower area surrounded by these is a cavity (space) 54. The foundation upper portion 52 includes the mounting portion 22 inclined backward at an angle θ like the above-mentioned foundation block 20, and an upper surface portion 26 provided in front of it, and includes at least one injection hole 35 penetrating a part of the upper surface portion 26 for injecting concrete 7 into the space 54 between the foundation front wall portion 51 and the foundation rear wall portion 53.

[0052] Similarly to the above-described foundation block 20, the foundation block 50 includes a contact area 22c in the mounting portion 22 that contacts at least the front and rear of the bottom surface portion 13 of the retaining wall block 10 at the bottom, and the width A of the contact area 22c in the front-rear direction is longer (wider) than the thickness B of the retaining wall block 10 at the bottom. Similarly to the above-described foundation block 20, the foundation block 50 includes a foundation rear surface portion 23 that is at least partially inclined backward so as to satisfy condition (1), (2) or (3). In this example, the rear surface portion 23 rises from the rear of the foundation bottom surface portion 25 and has a shape that includes a portion where the angle of inclination backward changes midway through the rise, but similar to the above-described foundation block 20, various variations are possible. Other parts common to the foundation block 20 are given common reference numerals and detailed explanations are omitted (the same applies to the following embodiments), but the foundation block 50 is a foundation block suitable for constructing a gentle retaining wall 1 with the same functions as the foundation block 20. This foundation block 50 is made of concrete and, like foundation block 20, is prefabricated (precast) in a factory and then transported to the construction site for retaining wall 1 and installed there, allowing the foundation for retaining wall 1 to be constructed in a short period of time.

[0053] Although the foundation block 50 is relatively large, its main structure is made up of walls (wall portions) 51, 52, and 53, with an internal space 54. This allows for a reduction in weight, suppression of manufacturing costs, and a reduction in the labor required for transportation and on-site work. In addition, the foundation block 50 has haunches (haunch portions, inward protrusions) 59 at the connections (inner surfaces, inside) between the front and rear walls 51 and 53 and the superstructure 52, and is arch-shaped, thereby preventing an increase in weight and improving strength.

[0054] As shown in FIG. 13(b), the foundation block 50 includes an injection hole 35 provided on the upper surface 26 of the foundation upper portion 52, and concrete 7 can be injected through this injection hole 35 into the space 54 surrounded by the wall bodies 51, 52, and 53 when constructing the foundation 2 of the retaining wall 1, and the foundation block 50 can be fixed to the ground or foundation concrete 2a. The foundation block 50 of this example is configured so that the injection hole 35 has an upper opening 35a that appears on the upper surface 26, and the concrete 7 can be injected into the internal space 54 from the injection hole 35 independently of the retaining wall block 10, whether before or after the retaining wall block 10 is mounted. Therefore, the concrete 7 injected into the foundation block 50 may be of the same quality as the concrete injected into the retaining wall block 10, or may be of a different quality. In addition, the vertical grooves 28 on both side surfaces 27 of the foundation block 50 are also configured by cutting out the sides of the upper surface 26, and the concrete 7 can be injected from the upper surface 26.

[0055] As shown in the cross section of Figure 15, the injection hole 35 provided in the foundation block 50 is a tapered hole in which the width of the upper opening 35a in the front-to-rear direction is wider than the width of the lower opening 35b in the front-to-rear direction. This makes it easy to inject concrete 7 from above the injection hole 35, and also suppresses cross-sectional loss due to the injection hole 35 in the superstructure 52, thereby suppressing a decrease in strength of the foundation block 50 due to the injection hole 35. Figure 15 shows an example of a retaining wall 1 with a slope of 10.5%, but the slope may be 10%, or 10.5% or more.

[0056] As shown in Figure 14(d), the bottom surfaces of the front and rear wall sections 51 and 53 are provided with recesses (grooves) 37 suitable for inserting jigs such as a crowbar to facilitate fine adjustment of the position and height of the foundation block 50 when constructing the foundation 2 of the retaining wall 1. Four grooves 37 are provided, distributed in the front, back, left and right directions, but the number is not limited to this. These grooves 37 may be used to attach members or tools such as packings or wedges for maintaining the results of fine adjustments to the height and inclination of the foundation block 50.

[0057] Fig. 16 shows another example of a foundation block 50. Fig. 16(a) is a perspective view of the foundation block 50, and Fig. 16(b) shows the state in which the lowest retaining wall block 10 is mounted on the foundation block 50. This foundation block 50 has two injection holes 35 provided on the upper surface 26, and concrete 7 can be more easily injected into a cavity (space) 54 in the lower area surrounded by a foundation front wall portion (front wall) 51, a foundation rear wall portion (rear wall) 53, and a foundation upper portion (superstructure) 52 that connects the upper sides of these and has a mounting portion 22 provided thereon, when constructing the foundation 2.

[0058] In the foundation block 50 shown in Fig. 16, a plurality of injection holes 35 are arranged side by side in the longitudinal direction (horizontal direction, lateral direction) of the upper surface portion 26. An example of the longitudinal (horizontal direction, lateral direction) length of the foundation block 50 is 1500 mm, but it may be 1000 mm, 2000 mm, 3000 mm, 4000 mm (4 m) or more. When the horizontal length of the foundation block 50 is longer, two or more injection holes 35 may be arranged side by side in the horizontal direction accordingly.

[0059] 17 to 19 show further examples of different foundation blocks 50. FIG. 17(a) is a perspective view of the foundation block 50, and FIG. 17(b) shows the state in which the bottom retaining wall block 10 is mounted on the foundation block 50. FIG. 18(a) is a plan view of the foundation block 50, FIG. 18(b) is a front view of the foundation block 50, FIG. 18(c) is a rear view of the foundation block 50, FIG. 18(d) is a bottom view of the foundation block 50, and FIG. 18(e) is a left side view of the foundation block 50. The right side view of the foundation block 50 is symmetrical to the left side view. FIG. 19 shows how the retaining wall blocks 10 are stacked to construct a retaining wall 1 with a slope of 10.5% using the cross section XXI-XXI of the foundation block 50.

[0060] This foundation block 50 is also a relatively large foundation block 50, with an example of a size being about 1000 mm in height, and includes a foundation front wall portion (front wall) 51, a foundation rear wall portion (rear wall) 53, and a foundation upper portion (upper structure) 52 that connects the upper sides of these and is provided with a mounting portion 22, with the lower area surrounded by these forming a cavity (space) 54. The foundation upper portion 52 includes the mounting portion 22 that is inclined backward like the above-mentioned foundation block 20, and an upper surface portion 26 provided in front of it, and includes at least one injection hole 35 that penetrates a part of the upper surface portion 26 and the mounting portion 22 to inject concrete 7 into the space 54 between the foundation front wall portion 51 and the foundation rear wall portion 53. The injection hole 35 reaches the horizontal groove 24 provided on the mounting part 22, and as shown in Fig. 19, when constructing the retaining wall 1, the concrete 7 can be injected into the horizontal groove 24 through the inside of the retaining-wall blocks 10 stacked on the mounting part 22, and further, the concrete 7 can be injected into the space 54 inside the foundation block 50 through the injection hole 35. This allows the foundation block 50 and the retaining-wall block 10 to be connected even more firmly.

[0061] The foundation block 50 includes, on both side surfaces 27, vertical grooves 28 whose upper sides are inclined backward, and the upper portions of the vertical grooves 28 reach the V-shaped, U-shaped, or C-shaped horizontal grooves 24 provided on the mounting portion 22. Therefore, when constructing the retaining wall 1, the concrete 7 can be poured into the vertical grooves 28 by pouring the concrete 7 into the horizontal grooves 24 through the retaining wall blocks 10 stacked on the foundation block 50. Therefore, the multiple foundation blocks 50 arranged horizontally to form the foundation 2 of the retaining wall 1 can be more firmly connected by the concrete 7 poured into the vertical grooves 28. The injection hole 35 may be a tapered hole in which the upper opening 35a is larger (wider) than the lower opening 35b, as in the above example.

[0062] In addition, in this foundation block 50, an injection hole 35 is formed from the upper surface portion 26 to the mounting portion 22. Therefore, when the retaining wall block 10 is mounted on the foundation block 50, part of the injection hole 35 appears on the upper surface portion 26, as shown in Figures 17(b) and 19. Therefore, concrete 7 can be injected into the cavity (space) 54 in the lower half of the foundation block 50 directly from the top of the foundation block 50 (without going through the retaining wall block 10). Also, by injecting concrete 7 through the injection hole 35 before mounting the retaining wall block 10, it is possible to construct the foundation 2 in advance, independently of the retaining wall block 10.

[0063] Although this foundation block 50 is relatively large, the main structure is made up of walls (wall portions) 51, 52, and 53, and a space 54 is provided inside. This allows the weight to be reduced, manufacturing costs to be kept down, and the labor required for transportation and on-site work to be reduced. In addition, the foundation block 50 has haunches (haunch portions, inward protrusions) 59 on both the front and rear of the upper part of the space 54 at the connection portions (inner surfaces, inside) between the front and rear walls 51 and 53 and the superstructure 52, or is arched, thereby preventing an increase in weight and improving strength.

[0064] As shown in Fig. 9 and Fig. 19, etc., this specification discloses a construction method for a block masonry retaining wall 1 with a gradient of at least 10%. This construction method includes stacking a plurality of retaining wall blocks 10 on a foundation block 20 or 50, each of the plurality of retaining wall blocks 10 including a front portion 11 and a bottom portion 13 that are provided to form an acute angle β. The stacking includes mounting the bottom portion of the bottommost retaining wall block 10 on the foundation block 20 or 50 in a state in which the bottom portion of the bottommost retaining wall block is tilted backward at an angle θ. The foundation block 20 or 50 may include a first horizontal groove portion 24 in the mounting portion 22, and may further include pouring concrete 7 into the first horizontal groove portion 24 through the bottommost retaining wall block 10.

[0065] The foundation block 50 includes a front foundation wall portion 51, a rear foundation wall portion 53, and an upper foundation portion 52 connecting the upper sides thereof and having a mounting portion 22 provided thereon, and the upper foundation portion 52 may include an upper surface portion 26 provided in front of the mounting portion 22, and at least one injection hole 35 penetrating at least a portion of the upper surface portion 26 and reaching a space 54 between the front foundation wall portion 51 and the rear foundation wall portion 53, and may further include injecting concrete 7 into the space 54 between the front foundation wall portion 51 and the rear foundation wall portion 53 through the at least one injection hole 35 when constructing the retaining wall 1.

[0066] FIG. 20 shows another example of a foundation block 50. FIG. 20(a) is a perspective view of the foundation block 50, and FIG. 20(b) shows the state where the bottom retaining wall block 10 is mounted on the foundation block 50. This foundation block 50 has two injection holes 35 on the upper surface portion 26 and the mounting portion 22, and the concrete 7 can be more efficiently injected into the cavity (space) 54 in the lower area surrounded by the front wall 51, the rear wall 53, and the superstructure 52. An example of the length of the longitudinal direction (horizontal direction, lateral direction) of the foundation block 50 is 1.5 m, but it may be 2 m, 3 m, 4 m or more, and two or more injection holes 35 may be arranged horizontally according to the horizontal length of the foundation block 50.

[0067] FIG. 21 shows a side view of yet another example of a foundation block 50. This foundation block 50 is also a block for constructing a retaining wall 1 by stacking the retaining wall blocks 10 on top of it. The foundation block 50 includes a foundation front wall portion (front wall) 51, a foundation rear wall portion (rear wall) 53, and a foundation upper portion (upper structure) 52 that connects the upper sides of these and is provided with a mounting portion 22, and the lower area surrounded by these structures is a cavity (space) 54. This foundation block 50 includes an arch structure (arch portion) 58 in which the connection portion between the foundation front wall portion 51 and the foundation rear wall portion 53 and the foundation upper portion 52 is curved as a whole. Furthermore, the foundation block 50 includes a protruding portion 37 provided behind the mounting portion 22 so as to abut against the back surface (rear surface, rear wall portion) 12 of the lowest retaining wall block 10. The foundation block 50 includes a mounting portion 22 that is wide (long) from front to back so as to mount a parallelogram-shaped retaining wall block 10 whose front and bottom portions intersect at an acute angle, and a rear surface portion 23 whose upper portion is inclined or curved rearward so as to support the mounting portion 22. It is therefore possible to adjust the inclination of the rear surface portion 23 so as to further widen the rear of the mounting portion 22 and provide a convex portion 37, thereby making it possible to increase the front-to-rear width of the foundation upper portion 52 including the convex portion 37. By providing the convex portion 37 behind the mounting portion 22, the rear surface portion 12 of the retaining wall block 10 stacked on the mounting portion 22 is supported, allowing the retaining wall blocks 10 to be stacked more stably.

[0068] FIG. 22 shows a side view of another example of a foundation block 20. The foundation block 20 is a block whose side or cross section is generally pentagonal or close to pentagonal, including a front portion 21, an upper surface portion 26, a mounting portion 22, a rear surface portion 23, and a bottom surface portion 25. The foundation block 20 includes a mounting portion 22 that is wide (long) from front to back so as to mount a parallelogram-shaped retaining wall block 10 whose front surface and bottom surface intersect at an acute angle, and a rear surface portion 23 whose upper portion is inclined or curved backward to support the mounting portion 22. Furthermore, the mounting portion 22 includes a protruding portion 37 provided behind the mounting portion 22 so as to abut against the rear surface (rear surface, rear wall portion) 12 of the lowest retaining wall block 10. It is possible to adjust the inclination of the rear surface portion 23 so as to further widen the rear of the mounting portion 22 and provide the protruding portion 37. By providing a protrusion 37 on the rear of the mounting portion 22, the rear surface 12 of the retaining wall block 10 stacked on the mounting portion 22 is supported, thereby making it possible to stack the retaining wall blocks 10 more stably. Furthermore, the mounting portion 22 is provided with a protrusion 32, which is adapted to engage with a recess 19 provided on the bottom surface 13 of the retaining wall block 10 of this example.

[0069] 23 shows how partition blocks (banding blocks) 60 are mounted on foundation blocks 20. The partition blocks 60 are stacked on the foundation blocks 20 at a predetermined interval, for example, about 10 to 20 m, on the left and right of the multiple retaining wall blocks 10. Each of the multiple stacked partition blocks 60 may include a rear surface portion 63 and a bottom surface portion 64 arranged at a right angle, and the bottom surface portion 64 of the bottommost partition block 60 may include a step or notch 65 that engages with at least a part of the mounting portion 22 of the foundation block 20 and at least a part of the foundation rear surface portion 23 behind the mounting portion 22.

[0070] A process called bulkhead construction may be included as one of the processes when constructing (manufacturing) the retaining wall 1. In the case of a wide small-to-medium-sized river or a bank (block masonry, block laying) that continues for a considerable distance, construction of bulkheads 71 ​​(bulkhead construction) using bulkhead blocks 60 at one location every 10 to 20 m is considered. The bulkheads 71 ​​are constructed between the retaining wall blocks (bank blocks) and have a width of about 300 mm, a depth of about 550 to 1000 mm, and a length that is almost the same as the length of the slope of the block masonry. The depth of the bulkheads 71 ​​is greater than the thickness (dimension B) of the retaining wall blocks 10. For example, when the retaining wall (bank) 1 is constructed using the retaining wall blocks 10 with a commonly used thickness B of 350 mm, the depth of the retaining wall (band work) 71 is 550 mm or 650 mm. One of the purposes of the partition wall 71 is to prevent muddy water from entering the back side of the retaining wall blocks 10 constituting the retaining wall 1, thereby preventing the block-built retaining wall (bank revetment) 1 from being destroyed.

[0071] Traditionally, these partition walls were constructed on-site using formwork. However, in recent years, they are often constructed by stacking precast blocks (partition blocks) about 2m long on top of foundation blocks. In order to reach the top of the retaining wall 1 (top, upper surface, slope height), several partition blocks are often connected together, and the partition blocks may be provided with projections and recesses (male and female) on both longitudinal ends for fitting together.

[0072] Fig. 23 shows how a partition wall 71 is constructed using the partition wall block 60. Fig. 24 shows an overview of the partition wall block 60. Fig. 24(a) is a plan view, Fig. 24(b) is a front view, Fig. 24(c) is a bottom view, Fig. 24(d) is a left side view, Fig. 24(e) is a right side view, and the back view is symmetrical to the front view. This partition wall block (band construction block) 60 is a concrete block that is prefabricated (precast) in a factory and has an overall rectangular parallelepiped shape. An example of the size is a thickness of 300 mm, a height (depth) of 550 mm, and a length of 2000 mm, but is not limited to this size.

[0073] The partition block 60 includes a front surface 65a and a back surface 65b extending in the longitudinal direction, upper surfaces 61 and lower surfaces 63 above and below the front surface 65a and the back surface 65b, and end surfaces 62 and 64 on both sides, each of which is provided at a right angle. When constructing the partition 71, one end surface 64 is mounted on the foundation block 20 as a bottom surface (bottom surface portion), and the lower surface 63 provided at a right angle to the bottom surface portion 64 is installed on the slope 5 as a rear surface portion. Furthermore, another partition block 69 is stacked on the other end surface 62 to construct the partition 71. The other end surface 62 of the partition block 60 may be provided with a recess 68a that is combined with a protrusion of the other partition block 69. Also, an insert 68b for attaching a connection plate may be embedded in the front surface 65a and / or the back surface 65b near the other end surface 62.

[0074] The partition block 60 has a bottom surface 64 provided with a V-shaped recess 66a at approximately the center of the bottom surface 64. As shown in FIG. 23, this recess 66a is shaped to engage with the rear contact portion (end portion) 22a, which is part of the mounting portion 22 of the foundation block 20, and the rear surface portion upper portion 23a, which is part of the foundation rear surface portion 23 at the rear of the mounting portion 22 and inclines backward. The recess 66a is also provided at a position where the upper end 64a of the bottom surface 64 abuts (comes into contact with) the front contact portion (end portion) 22b of the mounting portion 22. Therefore, the bottom surface 64 of the partition block 60 can be mounted on the mounting portion 22 of the foundation block 20. Furthermore, because the rear end 22a of the mounting portion 22 fits into the notch 66a, the partition block 60, whose bottom surface 64 and rear surface 63 are perpendicular to each other, can be combined with the foundation block 20 at a gradient of 10%, 15% or more, regardless of the inclination of the mounting portion 22, making it possible to construct a partition wall 71 with a gradient of 10% or more. The same is true when constructing a retaining wall 1 with a gradient of 15%, and by constructing the partition wall 71 with the partition block 60 of this example as the lowest block, a partition wall 71 with a gradient of 15% can be constructed.

[0075] The partition block 69 to be stacked on the partition block 60 may be a conventional partition block that is rectangular with six perpendicular faces and does not include the notch 66a, and this can reduce the effort and cost required to develop a new partition block with an acute angle. Note that when the partition block 60 is combined with the foundation block 20, a small gap may be generated between the mounting portion 22 and the bottom portion 64, but this can be filled by pouring concrete during construction.

[0076] Furthermore, the partition block 60 of this example has a notch 66a formed in the bottom surface 64, and by combining it with the rear of the mounting portion 22 of the foundation block 20, a portion 67 can be formed that extends in contact with the upper rear surface 23a of the foundation block 20. This makes it possible to impede the flow of water or soil behind the retaining wall blocks 10 that constitute the retaining wall 1, and to construct a partition wall 71 that can more efficiently prevent muddy water from entering behind the retaining wall 1, which is one of the purposes of the partition wall 71, and to prevent the block-built retaining wall (revetment) 1 from being destroyed.

[0077] Fig. 23(a) shows how partition wall blocks 60 are combined with foundation blocks 20, and Fig. 23(b) shows a partition wall 71 constructed using the partition wall blocks 60. After constructing the partition wall 71 using the partition wall blocks 60 and 69 along the slope 5, crushed stone 6 or the like is added as shown in Fig. 23(c) to construct a foundation (slope) with a predetermined thickness and gradient for stacking the retaining wall blocks 10 on the foundation blocks 20. Thereafter, as shown in Fig. 3 etc., the retaining wall 1 can be constructed by stacking the retaining wall blocks 10 on top of the foundation blocks 20.

[0078] It is also possible to make the partition wall block into an approximately parallelogram shape with acute angles, like the retaining wall block. However, in that case, it is not possible to provide a portion 67 that wraps around to the rear surface of the foundation block 20, and there is a possibility that the missing part will require the effort of pouring concrete on-site. In addition, it is not possible to construct a partition wall by combining it with an existing approximately rectangular (cuboid) partition wall block, which is not economical. By using this partition wall block 60 as the bottommost block (first block) to be combined with the foundation block 20, the remaining 18 partition wall blocks can be blocks manufactured using existing formwork, for example, when the length of the slope 5 is 20 m.

[0079] FIG. 25(a) shows another example of a partition block 60. This partition block 60 is an example to be combined with a foundation block 20 that does not have a V-shaped horizontal groove portion 24, and the bottom surface portion 64 of the partition block 60 includes a step (notch) 66a cut obliquely so as to contact the mounting portion 22. When the mounting portion 22 of the foundation block 20 includes a convex portion (projection) 32, the step 66a of the bottom surface portion 64 may be provided with a recess 19 to be combined with the convex portion 32. As shown in FIG. 25(b), by using this partition block 60 at the lowest stage, the partition wall 71 can be constructed using an existing rectangular parallelepiped partition block 69, similar to the above-mentioned partition wall 71.

[0080] FIG. 26(a) shows a different example of a foundation block 80. This foundation block 80 is a foundation block for constructing a block-laid retaining wall 1 with a gradient of 10.5% into a retaining wall block 89 for constructing a retaining wall 1 with a gradient of 10% when stacked horizontally as shown in FIG. 26(b). This foundation block 80 is a block whose side or cross section is generally pentagonal or nearly so, including a front portion 21, an upper surface portion 26, a mounting portion 22, a rear surface portion 23, and a bottom surface portion 25. The foundation block 80 includes a mounting portion 22 that is wide (long) from front to back and inclined backward at an angle θ (11 degrees in this example) so as to mount a retaining wall block 10 in the form of a parallelogram whose front surface portion and bottom surface portion intersect at an acute angle, and a rear surface portion 23 whose upper portion is inclined or curved backward to support the mounting portion 22.

[0081] In the foundation block 80 of this example, the rear surface portion 23 rises from the rear of the foundation bottom surface portion 25, and has a shape including a portion where the angle of inclination to the rear changes midway up, but similar to the foundation block 20 described above, various variations are possible. Other parts common to the foundation block 20 are given common reference numerals and detailed explanations are omitted, but this foundation block 80 is a foundation block suitable for constructing a loose retaining wall 1 with the same functions as the foundation block 20. This foundation block 80 is made of concrete, and like the foundation block 20, it is prefabricated (precast) in a factory and then transported to the construction site of the retaining wall 1 and installed there, allowing the foundation of the retaining wall 1 to be constructed in a short period of time.

[0082] 27 and 28 show further different examples of the foundation block 20. FIG. 27(a) is a perspective view of the foundation block 20 seen from below, and FIG. 27(b) is a perspective view of the foundation block 20 seen from above. FIG. 28 shows the side of the foundation block 20, showing how the retaining wall block 10 is mounted and the retaining wall 1 is constructed. The foundation block 20 is a block whose side or cross section is generally pentagonal or nearly so, including a front portion 21, an upper surface portion 26, a mounting portion 22, a rear surface portion 23, and a bottom surface portion 25. The foundation block 20 includes a mounting portion 22 that is wide (long) from front to back so as to mount the retaining wall block 10, which is a parallelogram whose front surface portion and bottom surface portion intersect at an acute angle, and is provided with a rear surface portion 23 whose upper portion 23a is inclined or curved backward to support the mounting portion 22. The lower portion 23b of the rear surface portion 23 is inclined backward so that the lower side is wider, and a wide bottom surface portion 25 is formed.

[0083] The foundation block 20 includes a vertical groove portion 28 extending vertically (up and down) on both side surfaces 27. The vertical groove portion 28 widens from an upper opening 28a toward a lower opening 28b, and the lower cross section (opening, cross-sectional area, opening area) 28b is wider (larger) than the upper cross section (opening, cross-sectional area, opening area) 28a. The concrete or mortar poured into the vertical groove portion 28 can suppress the vertical movement of the foundation blocks 20 that are constructed side by side in the horizontal direction. The vertical groove portion 28 reaches the bottom surface portion 13, and the concrete or mortar poured into the vertical groove portion 28 becomes one with the foundation concrete on which the foundation block 20 is installed, suppressing the phenomenon of the foundation block 20 moving or shifting. Furthermore, a fold 28c is provided on the inner wall of the vertical groove portion 28, so that the upper opening 28a and the lower opening 28b, which have a difference in opening angle, can be smoothly connected at the surface sandwiching the fold line 28c.

[0084] As explained above, retaining walls for small and medium-sized rivers and roads with a gradient of 3 to 5 minutes and a block masonry height of 5m or less are constructed by stacking retaining wall blocks on a flat foundation, with acute angles between the front wall and the bottom so that the gradient is 5 minutes, in accordance with the gradient of the slope of the retaining wall. When attempting to use these retaining wall blocks to construct a retaining wall for a large river with a gradient of 10% or more, for example a gentle gradient of 1.5%, it is necessary to adjust the gradient during construction, for example by placing stoppers between the retaining wall slope and the blocks to position them. Constructing a retaining wall with a gentle gradient in this way is more efficient than construction using conventional mortar blocks, but accurate construction is likely to require the skills of a contractor.

[0085] In the present invention, a foundation block is provided that is used in the lowest stage when constructing a block-built retaining wall with a gentle slope such as 10% or 1.5% slope, and that is configured so that when a retaining wall block with an acute angle between its lower end (bottom surface, bottom surface part) and its front surface (front surface part) when installed on a flat surface, for example, a 5% slope, is installed on its upper surface (mounting part, mounting surface), the slope of the front surface of the retaining wall block is gentle, for example, 10%, 1.5% or more. Therefore, by stacking the retaining wall blocks with a 5% slope on the foundation block, a retaining wall with a gentle slope such as 10% or 1.5% can be constructed. In addition, the angle of the back surface (foundation rear surface part) of this foundation block that rises from the lower end (rear end of the foundation bottom surface part) can be tilted (inclined) toward the back side (rear), and this can prevent the foundation block from becoming large, increasing in weight, and increasing costs. The rear portion may be such that the angle of the rear surface rising from the lower end of the foundation block is vertical and then tilts toward the rear surface halfway up.

[0086] This foundation block is used to construct a retaining wall with a gentle slope of 10% or 1.5%, but it is possible to suppress the angle of the mounting part (mounting surface) to less than 45 degrees. Therefore, in order to prevent the retaining wall block placed on the foundation block from slipping down to the back and becoming displaced during construction, the upper surface (mounting surface) that comes into contact with the retaining wall block may be provided with an uneven shape, a concave shape, or a convex shape, so that the retaining wall block and the foundation block can be fitted (engaged). Positioning by uneven engagement may be performed on the back side of the retaining wall block at the position where it comes into contact with the foundation block. The foundation front part of the foundation block may be shaped to widen as it goes downward. By using this foundation block, a block-built retaining wall with a gentle slope of 10% or more can be constructed simply by placing a retaining wall block with an acute front angle, for example a 5-minute slope, on the foundation block. This makes it possible to shorten the construction period and reduce the need for and effort required for adjusting the slope each time the retaining wall block is stacked. Furthermore, the connection between the foundation blocks and the retaining wall blocks is also strengthened, making it possible to construct a retaining wall that is highly durable against horizontal loads. [Explanation of symbols]

[0087] 1 retaining wall, 10 retaining wall blocks, 20, 50, 80 foundation blocks

Claims

1. A block wall with a slope of at least 10%, A foundation block and a plurality of retaining wall blocks stacked on the foundation block, Each of the plurality of retaining wall blocks includes a front surface and a bottom surface that are provided to form an acute angle, A retaining wall, wherein the foundation block includes a mounting portion on which the bottom portion of the lowest retaining wall block of the plurality of retaining wall blocks is mounted with the bottom portion tilted backward at an angle θ, and the angle θ satisfies the following condition. 10 degrees≦θ<45 degrees

2. In claim 1, The foundation block includes a contact area at the mounting portion that contacts at least the front and rear of the bottom surface portion of the bottom retaining wall block, A retaining wall, wherein the front-to-rear width of the contact area is longer than the front-to-rear thickness of the lowermost retaining wall block.

3. In claim 2, A retaining wall, wherein the foundation block includes a rear foundation portion at least a portion of which is tilted rearward.

4. In claim 3, A retaining wall, wherein the rear portion of the foundation includes at least a portion that is non-parallel to the front portion of the foundation and inclined rearward.

5. In claim 3, The rear surface portion of the foundation of the retaining wall rises from the rear of the bottom surface portion of the foundation and includes a portion that slopes backward halfway along the rise.

6. In claim 3, The rear surface portion of the foundation of the retaining wall rises from the rear of the bottom surface portion of the foundation and includes a portion at which the angle of inclination toward the rear changes midway along the rise.

7. In claim 3, A retaining wall having a convex portion behind the mounting portion, the convex portion being adapted to abut against the rear surface of the lowest retaining wall block.

8. In claim 1, A retaining wall, wherein the foundation block includes a mounting portion that engages with at least a portion of the bottom surface of the lowest retaining wall block.

9. In claim 8, A retaining wall, wherein the engaging portion includes at least one of an uneven portion, a convex portion, and a concave portion.

10. In claim 1, A retaining wall, wherein the foundation block includes a first horizontal groove portion in the mounting portion into which concrete flows via the lowest retaining wall block.

11. In claim 10, A retaining wall, wherein a second horizontal groove portion is provided on the bottom surface portion of the lowermost retaining wall block so as to face the first horizontal groove portion.

12. In claim 1, A retaining wall, wherein the foundation block includes longitudinally extending vertical grooves on both sides.

13. In claim 12, A retaining wall, wherein the vertical groove has an upper portion that slopes rearward.

14. In claim 12, The vertical grooves widen downwardly.

15. In claim 12, A retaining wall, wherein the vertical groove has a cross section wider at the lower part than at the upper part.

16. In claim 1, A retaining wall, wherein the foundation block includes a foundation front portion that is at least partially tilted backward.

17. In claim 1, The foundation block has a foundation front wall portion, a foundation rear wall portion, and a foundation upper portion that connects the upper sides of the foundation front wall portion, and is provided with the mounting portion; The upper part of the base has an upper surface provided in front of the mounting part, a retaining wall including at least one injection hole extending through at least a portion of the upper surface portion for injecting concrete into a space between the front foundation wall portion and the rear foundation wall portion.

18. In claim 17, A retaining wall, wherein an upper opening of the at least one injection hole reaches at least a portion of the mounting portion.

19. In claim 17, A retaining wall, wherein the at least one injection hole is a tapered hole in which the width of an upper opening in the front-to-rear direction is wider than the width of a lower opening in the front-to-rear direction.

20. In claim 17, A retaining wall having a plurality of injection holes provided in the longitudinal direction of the upper surface portion.

21. In claim 17, A retaining wall, wherein a haunch or arch portion is provided at the connection portion between the front wall portion of the foundation and the rear wall portion of the foundation and the upper portion of the foundation.

22. In claim 1, The method further includes stacking a plurality of partition wall blocks on the foundation block at a predetermined interval to the left and right of the plurality of retaining wall blocks, Each of the plurality of bulkhead blocks includes a rear surface portion and a bottom surface portion that are disposed at a right angle to each other, A retaining wall, wherein the bottom surface of the lowest partition block of the plurality of partition blocks includes a step or notch that engages with at least a portion of the mounting portion of the foundation block and at least a portion of the foundation rear surface rear of the mounting portion.

23. In any one of claims 1 to 22, A retaining wall, wherein each of the plurality of retaining wall blocks is a retaining wall block for forming a retaining wall with a 3 / 4 or 5 / 8 slope when the bottom portion is stacked horizontally.

24. In any one of claims 1 to 22, The block wall in question has a slope of 15%. A retaining wall, wherein each of the plurality of retaining wall blocks is a retaining wall block for forming a retaining wall with a 10% slope when the bottom portions are stacked horizontally.

25. A foundation block according to any one of claims 1 to 21.

26. A foundation block for building a retaining wall by stacking retaining wall blocks, the front surface and the bottom surface of which are provided so as to form an acute angle, The retaining wall block has a mounting portion on which the bottom surface of the retaining wall block is mounted in a state inclined backward, The mounting portion is a contact area that contacts the bottom surface of the retaining wall block at least at the front and rear, and includes a contact area that is longer in the front-to-rear direction than the front-to-rear thickness of the retaining wall block.

27. 27. In claim 26, A foundation block having a rear foundation surface that is at least partially inclined rearward.

28. 27. In claim 26, A foundation block having a foundation front surface and a foundation upper surface provided between the foundation front surface and the mounting portion.

29. 27. In claim 26, A foundation block having a convex portion behind the mounting portion that is adapted to abut against the rear surface of the retaining wall block.

30. 27. In claim 26, A foundation block, wherein the mounting portion includes a portion that engages with at least a portion of the bottom surface of the retaining wall block.

31. 27. In claim 26, A foundation block further having a first horizontal groove portion provided in the mounting portion so that concrete can flow through the retaining wall block.

32. In claim 26, The foundation block further has longitudinal grooves on both sides.

33. 27. In claim 26, A foundation block further having a groove extending in the front-to-back direction, the groove being provided at the position where the mounting part contacts the retaining wall block, for attaching a gasket that adjusts the height of the retaining wall blocks when stacked.

34. 27. In claim 26, A foundation block further having a groove extending in the front-to-back direction, the groove being provided at the position where the mounting part contacts the retaining wall block, for inserting a jig for adjusting the position of the retaining wall blocks when stacked.

35. 27. In claim 26, A foundation block including a front portion of the foundation that is tilted backward at least in part.

36. 27. In claim 26, The base includes a front wall portion, a rear wall portion, and an upper portion of the base that connects the upper sides of the front wall portion and the rear wall portion and is provided with the mounting portion; The upper part of the base has an upper surface provided in front of the mounting part, and at least one injection hole extending through at least a portion of the upper surface for injecting concrete into a space between the front foundation wall and the rear foundation wall.

37. 37. In claim 36, A foundation block comprising a plurality of injection holes arranged in a line in the longitudinal direction of the upper surface portion.

38. A foundation block according to any one of claims 26 to 37; A retaining wall having a plurality of retaining wall blocks stacked on top of the foundation blocks.

39. A method for constructing a block masonry retaining wall with a slope of at least 10%, comprising the steps of: Stacking a plurality of retaining wall blocks on a foundation block; Each of the plurality of retaining wall blocks includes a front surface and a bottom surface that are provided to form an acute angle, A construction method in which the stacking step includes mounting the bottom portion of the lowest retaining wall block of the plurality of retaining wall blocks on the foundation block with the bottom portion tilted backward at an angle θ, wherein the angle θ satisfies the following condition. 10 degrees≦θ<45 degrees

40. 40. In claim 39, The foundation block includes a first lateral groove portion in the mounting portion, The construction method further comprises pouring concrete into the first horizontal groove portion through the lowest retaining wall block.

41. 40. In claim 39, The foundation block includes a front wall portion, a rear wall portion, and an upper portion of the foundation that connects the upper sides of the front wall portion, the rear wall portion, and the mounting portion. The upper portion of the foundation includes an upper surface portion provided in front of the mounting portion, and at least one injection hole that penetrates at least a part of the upper surface portion and reaches a space between the front wall portion and the rear wall portion of the foundation. The construction method further comprises injecting concrete into a space between the foundation front wall and the foundation rear wall through the at least one injection hole.

42. 40. In claim 39, A construction method in which each of the plurality of retaining wall blocks is a retaining wall block for forming a retaining wall with a 3 / 4 or 5 / 10 slope when the bottom portions are stacked horizontally.

43. 40. In claim 39, The block wall has a slope of 10.5%. A construction method in which each of the plurality of retaining wall blocks is a retaining wall block for forming a retaining wall with a 10% slope when the bottom portion is stacked horizontally.

44. In any one of claims 39 to 43, The method further comprises stacking a plurality of partition wall blocks on the foundation blocks at a predetermined interval on the left and right of the plurality of retaining wall blocks; Each of the plurality of bulkhead blocks includes a rear surface portion and a bottom surface portion that are disposed at a right angle to each other, A construction method in which the bottom surface of the lowest partition wall block of the plurality of partition wall blocks includes a step or notch that engages with at least a portion of the mounting portion of the foundation block and at least a portion of the foundation rear surface portion rear of the mounting portion.

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