US2677240A - Sea wall - Google Patents

Description

P. F. DANEL May 4, 1954 SEA WALL Filed Jan. 29, 1952 INVENTOR. BY Harm 17m! mmR/vEY Patented May 4, 1954 UNITED STATES PATENT OFFICE SEA WALL corporation of France Application January 29, 1952, Serial No. 268,727

Claims priority, application France February 2, 1951 10 Claims.

The present invention relates to structures such as sea walls, jetties or the like which are exposed on one side to the action of the sea.

Such sea walls have sometimes been constructed from large blocks, for example, concrete blocks, disposed side by side and in superposed layers to form structures having substantially vertical walls on the seaward side.

The blocks commonly used in such structures are large and heavy, so that they may better resist the action of the waves. They are commonly laid one on the other without the use of mortar or the like. Because of their large size, such blocks, as commonly constructed, have more or less rough or irregular surfaces. Such roughness and irregularities could be eliminated by a finishing operation or by more careful fabrication, but either of those smoothing operations would greatly increase the cost of the blocks.

Such roughness and irregularities in the surfaces of the blocks have heretofore been regarded as inconsequential. It has now been discovered that these surface irregularities produce a serious structural weakness in the wall which may lead to its eventual destruction by the waves. roughness of the surfaces results in the existence of interstices between the blocks. As the waves impinge on the structure, the kinetic energy of the moving water is converted suddenly into pressure energy, with resulting local high pressures which force the water into these interstices. The pressures created in the interstices between and under the blocks may become great enough to lift and twist the blocks and thereby tear the wall apart. Although the blocks may be tilted only slightly toward the rear or one against the other, the Water in the interstices is under such a great pressure that it tends to shift the blocks so that they pivot about their zone of best contact with the other blocks. The destruction of the wall, once begun in this manner, may proceed to completion.

An object of the present invention is to improve sea walls so as to eliminate these defects.

This and other objects of the invention are attained by providing blocks for the construction of sea walls including pressure relieving conduits extending from the sheltered face of the blocks toward the exposed face and communicating with the interstices between the blocks so as to relieve any high pressure which may exist therein due to the action of the Waves. The seaward sides of the blocks are formed without such conduits. On the contrary, the abutting surfaces of the blocks adjacent the seaward side are formed to fit each other as closely as possible.

The

In a preferred embodiment of the invention, a, lateral surface of the block is provided with a channel extending parallel to the exposed face and closely spaced therefrom. This channel col- 6 lects any water which may filter through the interstices between the abutting surfaces of the blocks. Water pressures greater than atmospheric may exist between the blocks only in that portion of those interstices that is defined by the 50 small marginal areas of the abutting surfaces which lie between the channel and the exposed face. Those marginal areas must be made wide enough so as to make the Wall substantially water-tight and prevent the channels from being opened through to the seaward face in the course of normal wear. On the other hand, the marginal areas must be limited in Width in order to limit the force produced by the pressure which may exist in the interstices between the blocks adjacent such marginal areas. It has been found that the width of the marginal area should be no greater than one-fifth of the total width of the block, but should always be at least ten centimeters (3.94 inches).

Several embodiments of the invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a vertical cross-sectional view of a sea wall including a. block constructed in accordance with the invention, taken on the line II of Fig. 2.

Fig. 2 is a plan view of the wall of Fig. 1.

Fig. 3 is a cross-sectional view similar to Fig. 1, showing a modified form of block, taken on the line III-III of Fig. 4.

Fig. 4 is a plan View of the block of Fig. 4.

Figs. 5 and 6 are plan views of modified forms of sea walls employing multiple rows of blocks.

Referring to Figs. 1 to 3, there is shown a wall comprising a series of blocks l, resting on a bench or seat 2. The blocks 2 are generally in the form of a parallelepiped having a seaward face la and an opposite sheltered face lb, connected by lateral surfaces to. The term lateral surface is here applied to the upper, lower and end surfaces of the blocks. The lower lateral surface lc is provided adjacent the face la with a margin 3 which fits closely against the seat 2. The inner edge of the margin 3 is defined by a channel 4 formed in the bottom of the block i and extending parallel 0 to the seaward face la. The channel 4 communicates with the sheltered face ib of the block through a conduit 5. Although the channel 4 is shown in the lower lateral surface of block I, such channels may be provided in any or all of the lateral surfaces,

As shown in Fig. 2, the blocks l are aligned so 3 that the ends of the channels 4 in adjacent blocks communicate with one another.

When a wave strikes the wall, much of its kinetic energy is converted into pressure energy. As is well known, this pressure energy may be sufficient to lift a large quantity of water as high as the wall or even higher. This high pressure may force water into the interstices, such as the one between the margin 3 and the seat 2. Any water passing between those parts will flow into the channel 4 and the conduit 5. The channel 4 and the conduit 5 have cross-sectional areas which are much greater than that of the path of water flow between the margin 3 and the seat 2. It is preferable to reduce the crosssectional area of that path to a minimum, and it is therefore permissible to make the margin water-tight through the use of mortar or the like. The possibility of excessive pressure between the blocks I and the seat 2 is further reduced by the reduction in the dimensions of the interstice between the channel 4 and the exposed face la of the block. The stability of the block and of the complete wall are thereby greatly improved as compared to conventional blocks.

As pointed out above, the margin should be at least 10 centimeters in width, but not more than one-fifth of the width of the block. Any water under high pressure in the interstice between margin 3 and seat 2 is then not likely to lift or move the block, because the area on which it acts is small compared to the total block surface. Since the conduits 4, 5 are in communication with the atmosphere, they are effective to relieve any pressure.

In the embodiment shown in Figs. 3 and 4, the conduits have the form of grooves l in the bottoms of the blocks 6. The lower surface of the block 6 has at its forward edge a margin 3 corresponding to the margin 3 of Fig. 1 and defined by the ends of the grooves 1. Each block 6 has a seaward face 6a, a sheltered face 61), and lateral surfaces 50. The operation of this structure is similar to that of Figs. 1 to 3. Any water infiltrating past the margin 8 flows out through the conduits 1.

As in the case of the channels 4 of Figs. 1 and 2, the grooves I may be in any other lateral face of the block instead of the bottom face. Grooves on channels in the upper face are of utility only where another layer of blocks is laid on top of that upper face, as is done in many cases. In the case of the lower layer of blocks, grooves or channels may be formed in the underlying bench or seat instead of being formed in the lower face of the block.

Figs. 5 and 6 illustrate modified forms of wall construction in which each layer of blocks in the wall consists of two or more rows of blocks disposed one behind the other- 1 In Fig. 6 the blocks on the seaward side of the wall are identical with the blocks of Figs. 1 and 3. The blocks 9 in the row behind the blocks l are of similar external shape, but have only a single straight passage l formed therein. The passages 10 in the respective blocks are aligned with the passages in the blocks of the seaward row. The passages [0 provide communication between the passages 5 and the sheltered side of the wall.

Fig. 6 shows a modified form of wall construction wherein the blocks H of the seaward row are staggered with respect to the blocks l2 of the row behind. The construction of the blocks H is generally similar to that of the blocks I,

except that the central conduits 5 of Fig. 1 are replaced by laterally offset conduits l3. Similarly, the central conduits ID of the blocks 9 of Fig. 5 are replaced in the blocks 12 by offset conduits I4 which are aligned with the conduits I 3 in the blocks H.

Blocks constructed in accordance with the present invention may be produced at a cost not substantially greater than that of conventional blocks. The margins 3 or 8 along the seaward edge of the lateral faces of the block may receive a finishing treatment, while the other parts of the block surface need not be finished. If the blocks are made of concrete the channels 4 and the conduits 5 may be formed by inserts in the mold. In the case of the channels 4, these inserts may rest on the bottom of the mold. For the conduits 5, prefabricated pipes may be used. These may or may not be spaced from the bottom of the mold and in effect form a reinforcing frame for the concrete block.

It should be understood that the invention is not limited to the specific embodiments shown and described, but includes all mechanical equivalents thereof. For example, structures may be provided having conduits extending along other lateral faces of the blocks, and other arrangements of the blocks may be used. Conventional means for producing a more stable structure such as interlocking surfaces, mortises and tenons and the like, may be used.

I claim:

1. A wall exposed on one side to the action of the sea, comprising a plurality of abutting blocks, said blocks having the marginal areas of their abutting surfaces adjacent their seaward sides closely fitting to restrict the flow of water between the blocks, said blocks having conduits formed therein and providing liquid communication between the sheltered sides of the blocks and said abutting surfaces at points spaced from said seaward sides by said marginal areas, said conduits being effective to relieve water pressures built up between said blocks by the action of the waves.

2. A wall as defined in claim 1, in which said conduits include straight parallel passages extending between said points and said sheltered sides.

3. A wall as defined in claim 1, in which said conduits are straight parallel passages extending along said abutting surfaces between said points and said sheltered sides.

4. A wall as defined in claim 1, in which said blocks have formed therein transverse channels extending parallel to said seaward sides along said abutting surfaces.

5. A wall exposed onone side to the action of the sea, comprising a first row of blocks on the seaward side-of the wall, at least a second row of blocks between said first row and the sheltered side of the wall, said first row of blocks having the marginal areas of their abutting surfaces adjacent their seaward sides closely fitting to restrict the flow of water between the blocks and having conduits formed therein to provide liquid communication between the sheltered sides thereof and said abutting surfaces at points adjacent but spaced from said seaward sides, said second row of blocks having conduits formed therein to provide communication between the sheltered side of the wall and the conduits in said first row of blocks, said communicating conduits cooperating to' relieve pressures built up between the blocks by the action of the waves.

6. A block for forming a wall exposed on one side to the action of the sea, comprising a body having a face to be exposed to the sea, an opposite face to be sheltered from the sea and lateral surfaces connecting said faces, said lateral surfaces having a substantially smooth marginal area adjacent said exposed face, said body having formed therein at least one conduit providing liquid communication between the sheltered face of the block and at least one of said lateral surfaces adjacent the inner edge of said marginal area, said conduit being effective to relieve any superatmospheric pressure existing at said one lateral surface.

7. A block as defined in claim 6, in which each said marginal area is at least ten centimeters wide and not more than one-fifth of the Width of the lateral surface.

8. A block as defined in claim 6, in which said body has the form of a parallelepiped, and said marginal area is defined on at least one of said lateral surfaces by a channel formed in said lateral surface and extending parallel to said exposed face.

9. A block as defined in claim 6, in which said body has the form of a parallelepiped, and said marginal area is defined on at least one of said lateral surfaces by the ends of a plurality of parallel channels formed in said lateral surface and extending from said marginal area to said sheltered face.

10. In a wall exposed on one side to the action of the sea and having interstices therein, means defining conduits of substantially greater volumetric capacity than said interstices and providing fluid communication between the sheltered side of the wall and said interstices at points adjacent but spaced from the seaward sides, said conduits being effective to relieve water pressure built up in said interstices by the action of the water.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Church July 12, 1904 OTHER REFERENCES Number

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