JPH07259048A - Concrete block for revetment - Google Patents

Abstract

PURPOSE:To facilitate the position adjustment of concrete blocks in continuity, allow unhardened concrete to reach every corner through enlargement of the space to the underlay, and enhance the tight attachment of the concrete. CONSTITUTION:The arrangement includes a swell-out part 2 provided in a position eccentric downward from the center of one of the side faces of each concrete block 1 formed as a plate, connecting position adjusting members 3, 4 provided near each side of the swell-out part 2 at the same level as the undcrsurface of the swell-out part, and an engaging recess 6 which is provided at the other side face of concrete block 1 confronting the first named side face and where the swell-out part 2 is detained. Therein the arrangement should be such that the over-part of the recess 6 is detained by the oversurface of the swell-out part. The under-part is formed as an inclination limiting surface whereby the connecting angle is adjusted by the members 3, 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a revetment concrete block used for revetment work on the sea or rivers.

[0002]

2. Description of the Related Art Conventionally, large-scale concrete blocks, which are also called tension blocks, product blocks, or formwork panels, have been used for revetment work on the sea or rivers, on surfaces such as roads and residential land, on slopes or stairs. It is used.

The concrete block laying work using these concrete blocks has been carried out as follows. That is, after the foundation of the laying surface on which the concrete block is laid is finished, a certain space is provided between the concrete block and the ground to be the laying surface while being supported by the supporting members such as jacks and spacers. To do. Then, fresh concrete is poured between the concrete block and the base to cure it. The laying work is completed when the concrete hardens.

[0004]

However, the above-mentioned conventional laying method has the following problems. That is, when concrete revetments are usually formed, a plurality of concrete blocks are continuously provided in multiple stages, but alignment, especially height adjustment, at these connecting portions is difficult, and the work requires a lot of time and labor. ing.

Further, not only when the concrete blocks are continuously arranged in a straight line, but also each concrete block is continuously arranged with a certain inclination angle along the curved laying surface. In some cases, the adjustment of the laying angle of each concrete block had to rely on the skill of the operator. for that reason,
The construction period is long and the construction cost is high. Further, since the above-mentioned positioning work is a heavy labor and requires skill, it is difficult to secure workers, and the finished state of the work is often uneven.

In particular, in recent years, there has been a tendency to reduce the number of concrete blocks in response to the demand for shortening the construction period and reducing costs, and as a result, one concrete block is becoming larger and heavier. Has become even more prominent.

In view of the above problems, the present invention makes it easy to align the concrete blocks that are continuously laid, shortens the construction period, and makes the finished construction uniform. The purpose is to provide a concrete block for seawall protection that can be beautifully done.

[0008]

In order to achieve the above-mentioned object, a concrete revetment concrete block according to the present invention is provided at a position displaced from the center of one side surface of a concrete block formed in a plate shape to the lower end side. A bulging part, a connection position adjusting member provided on both sides of the bulging part at substantially the same height as the lower surface of the bulging part, and the bulging part on the other side of the concrete block facing the one side. An engaging concave portion with which the projecting portion is engaged is provided. The upper surface of the engaging recess is an engaging surface that engages with the upper surface of the bulging part, and the lower surface is an inclination regulating surface whose connection angle is adjusted by the connecting position adjusting member. It is a thing.

A plurality of the bulging portions may be arranged in a straight line along the longitudinal direction of one side surface so as to be spaced apart from each other. Further, the connection position adjusting member may be constituted by, for example, a nut member attached to one side surface of the concrete block, and a bolt member which is screwed to the nut member so as to be capable of screwing and being detachable.

Note that a plurality of reinforcing bars may be provided so as to project on the bottom surface side. Furthermore, a plurality of positioning recesses may be provided on the bottom surface side for positioning the support member that supports the concrete block.

[0011]

The concrete block for revetment is provided with a bulging portion and an engaging concave portion for position adjustment when continuously laying, and the bulging portion side allows position adjustment. Is provided with a connection position adjusting member whose length is adjustable.

Therefore, when laying the concrete block for seawall protection, first the temporary placement of the first concrete block is performed, and then the engaging concave portion of the second concrete block is projected to the bulging portion of the first concrete block. Aim it continuously and place it temporarily. At this time, by adjusting the protrusion amount of the bolt serving as the connection position adjustment member in advance, the engagement position of the inclination regulating surface of the engagement recess with respect to the connection position adjustment member is regulated, and the connection position adjustment member with respect to the first concrete block is regulated. The alignment of the second concrete block is automatically performed.

After that, by pouring fresh concrete into the space between the foundation to be the laying surface and the first and second concrete blocks and hardening it, the first and second concrete blocks are fixed and laid. Construction is complete. At this time, the connection position adjusting member and the engagement recess are engaged with each other, so that the second
It prevents the concrete block from rising.

If necessary, these operations may be performed on the plurality of first and second concrete blocks in the same manner, and then the pouring operation of the fresh concrete may be performed.

[0015]

EXAMPLE In this example, the shape of a concrete block for revetment according to the present invention will be described first with reference to the drawings, and then a method for laying the concrete block for revetment will be described.

First, a concrete block 1 for revetment according to this embodiment is formed in a rectangular plate shape as shown in FIGS.

As shown in FIG. 1, the bulging portion 2 is provided at a position deviated from the center of one side surface 1a in the longitudinal direction toward the lower end side. The bulging portion 2 is formed in the longitudinal direction of the concrete block 1 and has a trapezoidal cross section with a narrow width on the front end side. The bulging portion 2 is, in this embodiment, both side portions 2A and 2B and a central portion 2C.
A plurality of them are spaced apart from each other.

That is, by arranging a plurality of bulging portions 2 on one side surface 1a of the concrete block 1 in a straight line along the longitudinal direction, the connecting position adjusting member, which will be described later, engages the adjacent concrete blocks. The angle is adjustable. The bulging portion 2 may be provided in series along the longitudinal direction of the one side surface 1a.

Further, as shown in FIGS. 4, 6 and 7, in the vicinity of both sides of the bulging portion 2 provided on the one side surface 1a, the same height position as the lower surface side of the bulging portion 2 is provided. Is provided with a nut member 4. The nut member 4 is embedded and attached by a molding method such as insert molding when the concrete block 1 is molded.
The nut member 4 is for screwing the bolt member 3 serving as a connection position adjusting member. That is, the bolt member 3 is screwed into the nut member 4, and the length of the protruding amount of the bolt member 3 can be adjusted by adjusting the screwing amount.

As shown in FIGS. 8 and 9, when carrying the concrete block 1, a hook member 5 for suspending the concrete block is screwed into the nut member 4 instead of the bolt member 3. You may do it.

Next, on the other side surface 1b in the longitudinal direction of the concrete block 1, as shown in FIG. 2, an engaging concave portion 6 with which the bulging portion 2 is engaged is provided in the longitudinal direction. As shown in FIG. 10, the engaging recess 6 has an upper surface serving as an engaging surface 6a engaged with the upper surface 2a of the bulging portion 2, and a lower surface serving as a connecting angle by the connection position adjusting member. The tilt regulating surface 6b is adjusted. Further, the engagement recess 6 is configured such that, when engaged with the upper surface 2a of the bulging portion 2, the height position of the upper surface side 1c of the concrete block 1 becomes flush. On the other hand, the inclination regulating surface 6b of the engaging concave portion 6 is configured so that the engaging position is regulated by the tip 3a of the bolt member 3 which serves as the connecting position adjusting member. Therefore, as shown by the broken line in FIG. 10, the engagement angle θ between the engaging recess 6 and the bulging portion 2 is engaged with the upper surface 2 a of the bulging portion 2 by the amount of protrusion of the bolt member 3. It is designed to be variable around the upper surface of the fitting recess 6.

Further, as shown in FIG. 3, the upper surface side 1c of the concrete block 1 has an appearance as the concrete block 1 arranged along a river or a shore, and has various types of unevenness. Design is given. In this example, a circular concave portion 9 is further formed on the concave portion 8 formed in a substantially square shape.

On the other hand, in this concrete block 1, as shown in FIGS. 2, 4 and 5, a block support member 7 composed of a plurality of reinforcing bars is provided in a protruding manner on the bottom surface side 1d. In this embodiment, the four block support members 7 are arranged in two rows. This block support member 7
Is formed so as to project from the bottom surface side 1d of the concrete block 1 in a substantially U-shaped cross section, and is embedded and attached when the concrete block 1 is molded.

The block support member 7 is for forming a space g between the concrete block 1 and the base 11 which is the bottom surface and the laying surface of the concrete block 1. In addition, as shown in FIG. 9, the block support member 7 is provided when carrying the concrete block 1.
It serves as an engaging member with a block holder described later. The block support member 7 improves the adhesion when the concrete block 1 and the base 11 are joined and fixed with ready-mixed concrete or the like.

Next, spacer positioning recesses 18 are provided near the corners on the bottom surface side 1d of the concrete block 1, respectively. The spacer positioning recess 18 is formed by insert-molding a recessed mold 18a when the concrete block 1 is molded. The spacer positioning recess 18 is for attaching a spacer that serves as a support member used for positioning for height adjustment when the concrete block 1 is arranged.

Next, a method for laying the concrete block for revetment according to the present invention constructed as described above will be described. 11 to 19 are diagrams showing a method of laying a concrete block for seawall according to the present invention in order of seawall construction.

First, as shown in FIG. 11, after foundation work is carried out at the laying position of the concrete block 1 by installing the crushed foundation stone 10, the foundation block 20, etc., the foundation 11 to be the laying surface is formed. The base 11 is formed by driving in soil, crushed stone or concrete.

The basic block 20 may be a normal trapezoidal one as shown in FIG. 11, but a basic block 20A as shown in FIG. 12 may be used. The base block 20A has a step portion 21 at a position corresponding to the engaging recess 6 of the concrete block 1 and is for facilitating the connection of the concrete block 1. That is, according to the basic block 20A, the step portion 21 replaces the bulging portion 2, and the step portion 21 and the concrete block 1 are replaced.
By engaging with the engaging recesses 6 of, the concrete block 1 can be easily positioned and arranged. Also, FIG.
As shown in 3, the first concrete block 1A
It is possible to use the same as the second and subsequent concrete blocks 1B.

When the weight of the concrete block 1 to be laid is large, it is desirable that the above-mentioned base 11 is appropriately flattened by injecting concrete.

Next, as shown in FIGS. 9 and 14, one concrete block 1 (1A) among a large number of concrete blocks carried in the vicinity of the site is hung by a wire 12 or the like using a crane or the like. It is temporarily arranged at a predetermined position along the surface of the base 11. At this time, for hooking the wire on the concrete block 1, as shown in FIG. 8, a hook member 5 for hanging is screwed onto a nut member 4 provided on one side surface 1a of the concrete block 1, and the hook member 5 for hanging is hooked. The wire 12 may be hooked on the hook member 5 of the above.

When carrying the concrete block 1, the rod-shaped portion 13 as shown in FIGS. 9 and 14 is used.
If the block holder 13 having a is used, it becomes easier to carry this concrete block.

The block holder 13 includes a bar-shaped portion 13a on a block support member 7 which is arranged on the bottom surface side 1d of the concrete block 1 and is made of a reinforcing bar having a substantially U-shaped cross section.
The concrete block 1 is inserted into the concrete block 1 and the hook 13b is hooked on the hook member 5 for positioning.
Can be lifted. That is, the concrete block 1 is lifted by pulling up the block holder 13 via the wire 12 with a crane or the like, and the concrete block is easily carried. At this time, the hook 13b prevents the concrete block 1 from slipping off from the rod-shaped portion 13a, and even if the rod-shaped portion 13a is damaged, the concrete block 1 is prevented from dropping. .

Further, the block holder 13 is provided with a plurality of engaging holes 13c as hooking portions for the wires 12, and the position at which the wires 12 are connected is variable, so that it is suitable for the slope of the construction surface. The bar-shaped part 13a is set at an angle so that the concrete block 1 can be tilted and moved appropriately.

Since the concrete block itself is placed above the placement surface due to the block support member 7, the block holder is attached to the block support member 7 on the bottom side 1d of the concrete block 1. The rod-shaped part 13a of 13 can be easily attached.

Even when such a block holder 13 is not used, the hanging hook member 5 is used.
If the wire 12 is hooked on the wire 12 and the wire 12 is inserted into the block support member 7 and hung around, the wire 12 can be reliably prevented from being unhooked.
It is possible to carry the concrete block 1 reliably and easily.

Instead of the above-mentioned crane, other suitable machines, instruments or vehicles such as chain blocks may be used. Even in this case, the concrete block 1
Is made to float from the mounting surface by the block support member 7, so that the concrete block 1 can be easily transported.

In the temporary arrangement, the base 1
Positioning in the direction along the surface of 1 and height positioning are performed. At this time, the bottom side 1 of the concrete block 1
In the case where a plurality of block support members 7 are arranged in d, at least the concrete block 1 is arranged at a position which is lifted up by the height of the block support members 7 with respect to the base 11. Become. Therefore, the worker does not pinch his arm or leg between the block and the ground, and safe work is possible.

Further, fine adjustment of the alignment of the concrete block 1 is performed. For fine adjustment of the position of this concrete block 1,
At the corners of the corner, a manual hydraulic jack 14 is arranged between the base 11 and the concrete block 1, and after supporting the concrete block 1 with these hydraulic jacks 14, the wire 12 and the block holder 13 described above are attached. Remove. By adjusting the heights of the four hydraulic jacks, the height position and the inclination of the upper surface side 1c of the concrete block 1 are finely adjusted.

For this fine adjustment, for example, the upper surface side 1c or the edge of the concrete block 1 may be aligned with the water thread previously provided based on the design drawing. FIG. 15 shows a state in which this fine adjustment has been completed. The hydraulic jack 14 used here is a low-floor type equipped with a bracket for supporting a load at a position lower than the upper end of the plunger, and the bottom side 1d of the concrete block 1 after adjustment. The work design is performed so that the width g of the space g between the base 11 and the surface is about 8 to 12 cm.

Next, as shown in FIG. 16, a spacer 15 having an adjustable length is arranged between the concrete block 1 and the surface of the base 11 in the spacer positioning recess 18 provided on the bottom side 1d of the concrete block 1. To do. The spacer 15 serves as a support member for adjusting and supporting the laying position of the concrete block 1. That is, by raising the spacer 15, the spacer 15 temporarily receives a part of the weight of the concrete block 1. Then, the hydraulic jack 14 is loosened and the hydraulic jack 14 is removed from the temporarily received concrete block 1. Thereby, as shown in FIG. 17, the first concrete block 1A is arranged at the final position.

If the spacer 15 serving as a supporting member is attached to the recess 18 in advance when the concrete block 1 is installed, the spacer 15 need not be attached after jacking up, and the detachment after attachment can be avoided. . In addition,
In this case, the concrete block 1 is the spacer 15
The height position can be adjusted without using the hydraulic jack 14 as long as the weight can be raised and lowered by the jack function of itself.

Then, in order to adjust the position of the second concrete block 1B continuously arranged following the first concrete block 1A, the second concrete block 1B of the first concrete block 1A and the second concrete block 1B of the first concrete block 1A are adjusted. A bolt member 3 serving as a connection position adjusting member is screwed into a nut member 4 provided below a bulging portion 2 provided on one side surface adjacent to the nut member 4, and the amount of protrusion of the bolt member 3 from the nut member 4 is increased. Adjust the length of.

Next, the arrangement of the second concrete block 1B adjacent to the first concrete block 1A arranged as described above will be described.

First, the same steps as in the case of the first concrete block 1A are carried out, and the second concrete block is placed at a predetermined position along the surface of the foundation 11 adjacent to the first concrete block 1A. Temporarily arrange 1B. At this time, the engaging recessed portion 6 provided on the other side surface of the second concrete block 1B is abutted against the bulging portion 2 provided on one side surface in the longitudinal direction of the first concrete block 1A so as to be temporarily arranged adjacent thereto. .

Therefore, the second concrete block 1B is the second concrete block 1B depending on the projecting amount of the bolt member 3 attached to the first concrete block 1A whose length has been adjusted in advance.
The position of the tilt restricting surface 6b in the engaging recessed part 6 is restricted, so that the first concrete block 1A is automatically positioned and arranged as shown in FIG.

Furthermore, when fine adjustment of the alignment of the second concrete block 1B is required, fine adjustment is performed using the hydraulic jack 14 and the spacer 15 as in the case of the first concrete block 1A. Should be done. In this case, the joint portion of the second concrete block 1B with the first concrete block 1A is the first concrete block 1A.
Since it is supported by the bulging portion 2 of the hydraulic jack 1,
4 or the spacers 15 may be temporarily received at only two positions on the side facing the above-mentioned joint portion.

By repeating the above steps in the same manner, an appropriate number of continuous concrete blocks are arranged. Then, as shown in FIG. 19, ready-mixed concrete 16 is poured into a space g between the concrete block 1 and the foundation 11 which is a laying surface. After that, an appropriate number of concrete blocks 1 are constructed and arranged in the same manner as described above, and a space g between the concrete block 1 and the base 11 is arranged.
Pour fresh concrete 16 into. By repeating these, the concrete block 1 is arranged in the entire construction area, and the fresh concrete 16 is poured into the space g to be cured. Then, by hardening the green concrete 16, the concrete block 1 is fixed and the laying work is completed.

At this time, the bolt member 3 serving as the connection position adjusting member and the engagement recess 6 are engaged with each other to prevent floating of the second concrete block 1B at the connection portion when the fresh concrete 16 is poured. It

As described above, if the concrete block laying method according to the present embodiment is used and the concrete block laying method is used, the laying work is extremely easy and the construction can be performed in a short time. In addition, it is possible to form an accurately adjusted revetment. Therefore, the construction period of the concrete block laying construction can be shortened, and the cost required for the construction can be reduced accordingly. Further, since the height position of the upper surface side 1c of the laid concrete block can be aligned easily and with high accuracy, a uniform and beautiful finished state can be achieved without being influenced by the skill level of the operator. In particular, it can be suitably applied to the construction work of a large-scale concrete block having a weight of about 1 ton or more.

Further, the concrete block 1 and the base 1
Since the space g between 1 and 1 can be made large, the flow of the green concrete 16 in the space g becomes good, and the green concrete 16 can be sufficiently spread to every corner of the space g. Therefore, it is possible to obtain a robust structure having good adhesion between the concrete block 1 and the base 11. In particular, in the case where a plurality of block support members 7 made of reinforcing bars are arranged on the bottom surface side 1d, the adhesion can be further improved.

Further, it is not necessary to finish the surface of the base 11 to be flat as in the conventional case, and if the spacer 15 can be used for temporary receiving, there may be unevenness.

Since the spacer 15 is embedded in the ready-mixed concrete 16, an inexpensive spacer having a simple structure may be used.

FIG. 20 is a sectional view showing an example of the spacer 15A. The spacer 15A includes a first bolt 15b having a left-hand thread and a second bolt 15c having a right-hand thread, which are erected on the base 15a.
They are connected by d. Then, by rotating the hexagonal long nut 15d, the first, second
The amount of protrusion of both bolts 15b and 15c from the hexagonal nut 15d is variable. Therefore, the height can be adjusted according to the length of the nut.

As a spacer similar to this, for example, a screw type jack used as a foundation of a scaffold for construction work can be used. Further, the bulging portion 2 on the one side surface side of the concrete block instead of the bottom surface side may be supported by the hydraulic jack or spacer. In this case, the spacer can be removed and reused after the ready-mixed concrete has hardened.

In the above-mentioned embodiment, the green concrete 16 is poured into the space g, but mortar, cement, and various other things may be poured.

In the above embodiment, the bolt member 3 and the nut member 4 are used as the connection position adjusting member for connecting the first concrete block and the second concrete block. Other shafts, nails or the like may be used as long as the amount of protrusion from one side surface can be varied and has a certain level of strength.

Further, in the above embodiment, the hydraulic jack 14 is arranged after the concrete block 1 is temporarily arranged, but the hydraulic jack 14 may be arranged in advance before the concrete block 1 is arranged. At that time, the spacer 15 may also be arranged in advance. Further, the hydraulic jack 14 may be omitted if the height position can be adjusted by the spacer 15A as described above.

The hydraulic jack 14 may be operated by hydraulic pressure from a hydraulic unit driven by a dynamic electric machine or an internal combustion engine. Furthermore, hydraulic jack 1
Instead of 4, a hydraulic jack or a screw type jack may be used.

Next, in the above-mentioned embodiment, the reinforcing bar having a substantially U-shaped cross section as the block supporting member 7 is attached to the bottom surface side 1d of the concrete block 1. The shape of the reinforcing bar is the concrete block described above. Other shapes may be used as long as they can support the. Even if this block support member 7 is not provided, it is possible to lay a concrete block by adjusting the position such as the inclination angle between the first concrete block and the second concrete block. Is.

In this embodiment, the plate-shaped rectangular concrete block has been described. However, it may be used for a polygonal block having two opposite sides, and a revetment formed in a staircase as shown in FIG. It may also be used for the concrete block 25.

[0061]

According to the present invention, the height position of continuous concrete blocks can be easily adjusted, the construction period can be shortened, and the finished state of construction can be made uniform and beautiful. Since the fresh concrete can be sufficiently spread by enlarging it, it is possible to provide a concrete block for seawall improvement in adhesiveness with the foundation to be laid.

[Brief description of drawings]

FIG. 1 is a perspective view of a concrete block for seawall according to the present invention as seen from the upper surface side.

FIG. 2 is a perspective view of the revetment concrete block seen from the bottom side.

FIG. 3 is a top view of the revetment concrete block.

FIG. 4 is a side view of the concrete block for seawall protection.

FIG. 5 is another side view showing a part of the concrete block for revetment by cutting away.

FIG. 6 is a cross-sectional view of the concrete block for seawall protection.

FIG. 7 is an enlarged perspective view of an essential part showing a state in which a bolt member is about to be screwed into the nut member of the concrete block for seawall protection.

FIG. 8 is an enlarged perspective view of an essential part showing a state in which a hook member is about to be screwed onto the nut member of the concrete block for seawall protection.

FIG. 9 is a perspective view showing a suspended state of the concrete block for seawall protection.

FIG. 10 is a cross-sectional view of essential parts showing an engaged state of the concrete block for seawall protection.

FIG. 11 is a diagram showing a state of revetment work using the concrete block for revetment according to the present invention, and is a schematic cross-sectional view showing a base forming step.

FIG. 12 is a perspective view of a basic block.

13 is a schematic cross-sectional view showing an arrangement state of revetment concrete blocks when the foundation block shown in FIG. 12 is used.

FIG. 14 is a diagram showing a state of the revetment work and is a schematic cross-sectional view showing a temporary placement step of the concrete blocks.

FIG. 15 is a diagram showing a state of the revetment work, and is a schematic cross-sectional view showing a fine adjustment process of the concrete block.

FIG. 16 is a diagram showing a state of the above-mentioned revetment work, and is a schematic cross-sectional view showing a state where a spacer is put on the bottom surface of the concrete block.

FIG. 17 is a diagram showing a state of the revetment work and is a schematic cross-sectional view showing a state where fine adjustment of the concrete block is completed.

FIG. 18 is a diagram showing a state of the revetment work, and is a schematic cross-sectional view showing a state in which concrete blocks are continuously arranged.

FIG. 19 is a view showing a state of the above-mentioned revetment work, and is a cross-sectional view showing a state where ready-mixed concrete is poured into a space between the concrete block and the foundation.

FIG. 20 is a cross-sectional view showing an example of a spacer.

FIG. 21 is a schematic cross-sectional view showing an example of a revetment completed using the concrete block for revetment of the present invention.

[Explanation of symbols]

 1 Concrete Block 2 Swelling Part 3 Bolt Member 4 Nut Member 6 Engagement Recess 7 Block Support Member

Claims (5)

[Claims] 1. A bulging portion provided at a position displaced from a center of one side surface of a concrete block formed into a plate shape to a lower end side, and substantially the same as a lower surface of the bulging portion in the vicinity of both sides of the bulging portion. A connection position adjusting member provided at a height position, and an engaging concave portion with which the bulging portion engages are provided on the other side surface of the concrete block facing the one side surface. A concrete block for seawall protection, wherein the portion is an engaging surface which is engaged with the upper surface of the bulging portion, and the lower surface is an inclination regulating surface whose connection angle is adjusted by the connection position adjusting member. 2. The revetment concrete block according to claim 1, wherein a plurality of the bulging portions are arranged in a straight line along the longitudinal direction of one side surface with a space therebetween. 3. The connection position adjusting member comprises a nut member attached to one side surface of the concrete block, and a bolt member that is screwably and removably screwed into the nut member. Concrete block for seawall protection. 4. The revetment concrete block according to claim 1, wherein a plurality of reinforcing bars are provided so as to project from the bottom side. 5. The concrete block for revetment according to claim 1, wherein a plurality of positioning recesses are provided on the bottom surface side for positioning a support member for supporting the concrete block.