EP0134296A1

EP0134296A1 - Engaging block for revetment

Info

Publication number: EP0134296A1
Application number: EP83108965A
Authority: EP
Inventors: Akira Kobayashi
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-09-10
Filing date: 1983-09-10
Publication date: 1985-03-20

Abstract

An engaging block for revetment wherein narrow abutting surfaces are frontwardly formed in four sides of a side portion, projected portions (2) are formed in a set of adjacent two sides, and recessed portion(3) are formed in a set of other adjacent two sides. When blocks are brought into engagement with each other, a clearance (4) formed as a result of fitting between the projected portion(2) and the recessed portion(3) is enlarged towards the rearward. Whereby a bending property is imparted to mutual blocks and seeping water in a levee body is scattered and drained from four sides of the blocks.

Description

This invention relates to blocks, so-called reveting blocks for use in a reveting construction in rivers or reservoirs, and more specifically, to an improvement in an engaging block for revetment which provides a unification of blocks by engagement with one another.
In conventional engaging blocks for revetment as shown in Fig. 1, an L-shaped projected portion B is formed in a set of adjacent side portions of a rectangular parallelepiped body A and an inverted L-shaped recessed portion C formed in the other set of side portions, whereby these projected portion B and recessed portion C are fitted and engaged with each other to unify blocks each other. This engaging block is easy in execution because there needs no filling with cement in a joint of a united portion as in prior art plain lined blocks, and said engaging block is being used as a process which is particularly suitable for a block levee protection in a slope of a gently inclined levee body.
However, in the aforementioned engaging blocks, the unifying portions are closely fitted each other and therefore, there is a water tightness and in addition, there is no bending property between the blocks. Therefore, in the event that a variation should occur in the ground of the levee body, the block levee protection is impossible to follow said variation to create a clearance between the ground of the levee body and the block levee protection, which leads to destruction therefrom.
In addition, since said block levee protection is water-tight, seeping water in the levee body resulting from displacement of water level stays as back-water in the back of the block levee protection, and said back is subjected to water pressure therefrom, resulting in a failure of revetment.
In order to discharge the back-water, attmpts are made in which notches D are formed in corners of the block or in which water removing holes are formed in the body of the block. In these proposals, however, water is concentrically removed through these notches D or holes, and therefore, aggregates such as gravel, sand, etc. flow out, which rather causes facilitation of damages to the revetment. Moreover, roots of plants enter into the revetment through these holes, disadvantageously damaging the revetment.
It is an object of the present invention to impart the engaging block an adequate degree of bending property and a good water permeability (not a concentrated drainage). In view of the fact that presently available blocks are made of concrete, the present invention has been achieved from a viewpoint of construction and shape of a unified portion of the blocks.
An engaging block for revetment in accordance with the present invention employs the following structures to achieve the aforesaid object That is, the block of the invention comprises (1) a block body in the form of a rectangular parallelepiped composed of a front, portion, a back portion and side portions, characterized in that (2) said side portion is formed with a narrow abutting surface leading to and along four sides of said front portion, a set of adjacent two sides being continuously formed with projected portions, a set of other adjacent two sides being continuously formed with recessed portions loosely fitted into said projected portions, and (3) a clearance formed as a result of fitting between said projected portion and said recessed portion is substantially gradually enlarged from the front portion towards the back portion.
The engaging block for revetment in accordance with the present invention has the following effects:

(1) Since the clearance formed in four sides of the side portion of the block is gradually enlarged towards the rear portion, the bending property is imparted to mutual blocks, whereby a block levee protection capable of following the deformation of a levee body can be formed. With the provision of said clearance, it is possible to freely execute the levee protection while being adjusted to a slope and a curvature of a levee body during the execution of the levee protection.
(2) Since the engagement of blocks each other is accomplished by engagement of abutting surfaces each other and by engagement of corner portions each other of said abutting surfaces and projected portions and recessed portions, blocks are accurately arranged each other, and said arranging operation is readily accomplished.
(3) Since seeping water of the levee body is dispersedly discharged from four sides of individual blocks, the drainage is not concentrated and therefore the aggregate is not stirred and the drainage speed is high. Further, since the clearance between the blocks is reduced towards the front portion, water pressure of the back-water is concentrated to further increase the drainage effect from the abutting surface. In additiona, the entry of outside water (river water and storage water) into the levee body is reduced by the close unification of the abutting surfaces each other.
(4) With the exception of water permeability, the abutting surfaces are closely unified to restrain entry of foreign matter such as sand, and therefore, the aggregate is moved out and roots of plants do not enter. Tnus, the levee protection is positively secured.

One way of carrying out the invention is described in detail below with reference to drawing which illustrate preferred embodiments, in which:

Figs. l(a), (b) are a partial plan view and a vertical sectional view, respectively, showing structure of a conventional engaging block;
Fig. 2 is a plan view of one embodiment of an engaging block in accordance with the present invention;
Fig. 3 is a side view of Fig. 2 as viewed from the right hand;
Fig. 4 is a sectional view taken on line X -X of Fig. 3;
Fig. 5 is an enlarged sectional view of an united portion;
Figs. 6(a), (b) are sectional views showing united portions in accordance with alternative embodiments of the present invention;
Fig. 7 is a sectional view showing the using mode of the block in accordance with the present invention; and
Fig. 8 is a plan view showing the using mode of the block in accordance with the present invention.

Figs. 2 to 5 show a preferred embodiment of an engaging block in accordance with the present invention.
In the figures, reference character H designates a block in accordance with the present invention, and 1 denotes a body of the block H. The block body 1 is substantially formed into a rectangular parallelepiped. Reference numeral 11 designates a front portion of the block, 12 a back portion(or a rear portion) and 13 a side portion.
The front portion 11 has a bulged stilling portion 11A. The stilling portion 11A has a function to scatter energy and still a stream of water by impingement of the stream of water(including waves) upon recessed and projected portions formed thereon and also has a function as a moderate anti-skid means for a person who walks on the face of slope of the block construction. Accordingly, the stilling portion 11A is not limited to the mode illustrated in the present embodiment but an alternative mode can be employed in which a suitable number of projections are provided on the front portion 11. Conversely, depressed portions can be provided in the front portion to form a stilling portion.
Reference numeral 13A designates abutting surfaces formed in a side portion 13, which abutting surfaces lead to the front portion 11 and are narrowly formed about four sides of the side portion 13. The abutting surface 13A has a function to maintain mutual positions of the blocks H which come into close abutment with each other when the blocks H are combined, and also has a function to maintain a water permeability (air permeability) due to the close unification therebetween to prevent entry of foreign matter such as sand and others. The width and shape of the abutting surface 13A are suitably determined in consideration of material and moldability of the block H within the range which satisfies with the aforementioned functions, that is, (1) loading property, (2) water (air) permeability, and (3) prevention of entry of foreign matter.
Reference numeral 13B designates a chamfered portion formed in the edge of the front poriton 11 of the block body, but this chamfered portion can be omitted if so desired. Reference numeral 13C designates a rear side portion at the rear of the side portion 13. This rear portion 13C can be also omitted if so desired depending on the shape of projected portion and recessed portion which will be described later.
Reference numeral 2 designates a projected portion formed in the set of the side portions 13 adjacent to each other. The projected portion 2 has a section in the form of a trapezoid and is formed leaving the abutting surface 13A frontwardly thereof and is formed along and continuous to the side of the side portion 13.
Reference numeral 3 designates a recessed portion formed in the set of the side portions 13 adjacent to each other. The recessed portion 3 has its shape so that it is loosely fitted into the projected portion 2, in other words, the recessed portion is fitted into the projected portion with a required clearance left therebetween. The recessed portion is likewise formed leaving the abutting surface 13A frontwardly thereof and is formed along and continuous to the side of the side portion 13.
Reference numeral 4 designates a clearance formed, in the side portion 13 of the block, between the projected portion 2 and recessed portion 3 opposed to each other and between rear side portions 13C, when the blocks are combined each other. The clearance 4 gradually enlarges towards the rearward(that is, in the direction from the front portion 11 to the back portion 12 of the block). That is, the following proportional relation is given,
wherein x represents the distance from the abutting surface 13A as a starting point to the reaxward, and ℓ represents the distance of the clearance between the opposed surfaces. Actually, however, it is often that in terms of moldability,the upper side of the projected portion 2 is. formed parallel to the bottom side of the recessed portion 3 and the rear side portions 13C are formed parallel to each other.
As one example, the block H of the present embodiment has the following particulars That is, in Figs- 2 and 3, the width I is 450 cm, the height J is 300 cm and the thickness K is 180 cm When this is made of concrete, the weight is approximately 50 kg, which is an allowable limit for one person who carries a block.
Figs- 6 (a) and (b) show further embodiments of a projected portion and a recessed portion. Fig. 6(a) shows a combination of a circular arc-like projected portion 2' and a circular arc-like recessed portion 3'. Fig. 6(b) shows a combination of an L-shaped projected portion 2" and recessed portion 3". In these embodiments, the rear side portion 13C is omitted.
Even in the embodiments shown in Figs- 6 (a) and (b), the technical matter with respect to the presence of the abutting surface 13A in the side portion 13 and the enlargement of the- clearance 4- continuous to the abutting surface 13A towards the rearwarded is the same as that of the embodiment previously illustrated.
Figs. 7 and 8 show the using mode of the- aforesaid blocks H- Fig- T is a longitudinal sectional view of a block levee protection, and. Fig. 8 is a plan view showing the arrangement of the blocks. A natural ground(that is, a body of a levee body) 5 has an inclined surface shaped as flat as possible, and a gravel layer composed of sand, broken stones or crushed stones is laid on the natural ground 5. The gravel layer 6 has functions (1) to substantially prevent the outflow of earth and sand in the natural ground resulting from the outflow of seeping water in the levee body, (2) to buffer the local sinking of the natural ground 5, and (3) to secure the workability of execution when the natural ground 5 is soft. A draft resisting material 7 formed of mat-like vegetable fibers of synthetic resin fibers and having a filtering property relative to water is laid on the gravel layer 6. The draft resisting matetial 7 has a function to prevent the outflow of earth and sand from the gravel layer 6 and the natural ground 5 resulting from the outflow of seeping water of the natural ground and also has a function to provide a flat execution surface so that the blocks may be readily laid. Blocks H are laid on the draft resisting material 7 while the projected portions 2 and recessed portions 3 thereof are placed in engagement with one another. It should be appreciated that in case the nature of the soil of the natural ground 5 is fine viscous, the draft resisting material 7 is directly laid on the natural ground 5, on which the gravel layer 6 is laid to place the blocks thereon.
The laying of the blocks H is accomplished in the following. Pits are formed while being divided by the bed sill of a longitudinal sill 81 and a lateral sill 82 which divide an execution area of the levee protection longitudinally (parallel to the water surface) and laterally (perpendicularly to the water surface). Blocks H are laid in the pits one by one successively in a zig-zag fashion from one side of the execution area, and a semi-block H' is placed in a fragmentary end present adjacent the bed sill, thus laying the blocks over the whole surface of the pits.
Without further elaboration, the foregoing will so fully illustrate the invention that others may, by applying the current or future knowledge, readily adapt the same for use under various conditions of service.
For example, although arrangement of the rectangular blocks H is shown in Fig. 8, any other shape of the blocks, such as hexagon, octagon and other polygons in cross-section, may be employed in accordance with the invention so far as the projected portions and recessed portions are placed in engagement with one another.

Claims

1. An engaging block for revetment comprising a block body(l) in the form of a rectangular parallelepiped composed of a front portion(ll), a back portion(12) and side portions(13), characterized in that said side portion(13) is formed with a narrow abutting surface(13A) leading to and along four sides of said front portion(11), a set of adjacent two sides being continuously formed with projected portions(2), a set of other adjacent two sides being continuously formed with recessed portions(3) loosely fitted into said projected portions(2), and a clearance(4) formed as a result of fitting between said projected portion(2) and said recessed portion(3) is substantially gradually enlarged from the front portion(11) towards the back portion(12).

2. An engaging block for revetment according to Claim 1, wherein the projected portion(2) and recessed portion(3) are in the form of a trapezoid.

3. An engaging block for revetment according to Claim l, wherein the projected portion(2) and recessed portion(3) are in the form of a circular arc.

4. An engaging block for revetment according to Claim 1, wherein the projected portion(2) and recessed portion(3) are in the form of an L-shape.

5. An engaging block for revetment according to Claim 1, wherein the front portion(ll) is provided with stilling portion (11A).