US 2008866 A
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Description (OCR text may contain errors)
July 23, 1935.
H. o.l HOFFARD REVETMENT Filed June 29, 19154 Mw/ ///l./
955x? mwwwwww N w Hro/dflorngd @3M M I Patented July 23, 1935 PATENT "OFFICE REVETMENT Harold Hoiard, Tacoma,` Wash., assigner of Y one-fourth to Myrle M."'Williams and onefourth to Alfred Cavanaugh,l both of Snohomish County, nearArlington, Wash.V
'pplicatiqnimne 29,1934, serial No. 733,074
' 6 claims.`
, My invention relates to. revetments, and to a method.V of revetting banks against erosion.
y ,A greatdeal of revetment work is being under-v taken in connection with iiood control operations,
Because `there are numerous `streams to guard againstand manyfpoints in each stream where the danger of erosion arises,q'whether. from the banks orfrom dikes, -it is necessary that any revetmentbe simple and inexpensive, It is further ldesirable that itbe of;such character that in the event itbe-broken or damaged it will be possible to repair and, replacedamaged partsl without undueexpense, loss of time, or ,special equipment. My invention incorporates allthese advantages, and in: addition provides a simple and inexpensive., method ofplacement, especially to protect the under-,water portions of-banks.
It is; therefore a general object of :theinvention to provide a'revetmentand a method of revettingv which has-the'various advantages specified and others. Among further advantages are v'that the action of stream ,flowon the revetment is not permitted by the structure of the revetment to gain access to the banks beneath the revetment. Another object is to provide a revetment which can be formed from elements which are readilyy made, usually locally, and which can be placed by hand labor.
With these and other advantages in mind, as will appear hereafter, my invention comprises the novel revetment as a whole and the novel method of revetting banks, as shown in the accompanying drawing, described in this specification,` and as will be more particularly defined by the claims which terminate the same.
In the accompanying drawing I have shown my revetment and the method of placing the same in an illustrative form, thereby illustrating the principles of my invention.
Figure 1 is a cross section through a stream and bank, showing the method of placing the revetment. l
Figure 2 is a plan view of the same.
Figure 3 is a detail plan view of adjacent elements of the revetment, showing the manner of securing the same together. Y
Generally speaking, my invention contemplates the employment of a series of blocks, preferably of concrete or like material, of a size permitting them to be handled by a man. These blocks may vary in shape, though preferably, because of the I'functional characteristics and because of the cheapness and ease with which they can bey prepared, they are square in shape. Each block is provided with devices whereby it can be secured to adjacent blocks, so that the whole forms a mat,
' and inthis-mat, and constituting one of the distinguishing features of my invention, the blocks are arranged in lines and rows which are placed ldiagonally,-that is tosay, at an angle to the direction ofk stream flow, so that when the mat is in place there will not be presented any continuous line or space in the mat running in the direction lof, stream iiow. As a result the stream fiow is broken upby small eddys, and the stream tends to silt'in the spaces between blocks rather than'to wash `out material from between them, so that in the course of a comparatively short time the mat becomes in effect a smooth surface consisting of connected diagonally arranged blocks with the interstices silted in.
It'is valso a distinctivefeatureof myinvention. that a method is provided whereby the under- Waterfportion of the banks `may be properly pro-` tected by sucha matV forming an integral extension of-,the abovef-waterportion, and thefWhole mat can be constructed conveniently-above thewater, and-,thentneunderfwater portion sunk into place.
Referring to the drawing, it will be observed that a number of blocks I are provided, which, as indicated, are preferably square in shape. Each of these is provided with securing means, and in this instance each block is provided with a pair of crossed rods 2 terminating at one side of the block in an eye 3, and at the opposite side of the block in a. hook 4. When laid in the mat the eyes on two sides of a block are engaged with the hooks at the adjacent sides of the adjoining blocks, and by bending these hooks over the eyes the blocks are secured together. Nevertheless, if a block is broken it can be removed and the hooks bent back suiciently to allow reengagement of new blocks, thus accomplishing the repair of any broken section of the revetment.
The blocks are placed diagonally, as shown best in Figure 2. They are laid on the above-water portion of the bank of the stream, as high as may be necessary to protect the bank, and when a number of these blocks have been thus laid, they will resist any tendency to pull them along the bank, although guy ropes or cables may be connected to the hooks or eyes as may be necessary to anchor the mat preliminary. Now a raft 5, or lany suitable float, kmay be moored alongside the bank where the mat has been laid, and this will serve to support an integral extension of the mat out over the surface of the water. The outward extension from the margin of the stream will be suicient that when the mat isr permitted to sink it will sink to such extent and extend downward and outward as is necessary to protect the underwater portion oi the bank. 'I'hus if the underwater portion be comparatively shallow at one point, the extension of the mat need not be so great as Where the bank extends to a deeper portion of the bottom of the stream. 1 l
When the extension mat has been laid ongthe raft to an extent suiiicient to protect the underwater portion of the bank the raft is pulled, preff erably in a down-stream direction, from under the mat, and this portion of the mat, consisting of blocks all secured together, sinks as a vrunit and lies along the under-waterlpart of the bank.
This may be continued, the mat being laid'alongy the bank above water, and the extension, being formed integrally therewith and connected tothe sunken portion, is laid on the raft, and the raft is progressively pulled along, sinking the underwater portion of the mat as the work progresses.
What I claim as my invention isf l g f l 1. A revetrnent comprising a pluralityjof slightly spaced blocks and means securing eachY one to all adjoining blocks, to form a ilexible mat, said blocks being so disposed, relative to theY direction of stream ow, that no continuous line between adjacent blocks is presented parallel to Vthe stream flow.
2. A revetment comprising a plurality ofv substantially square blocks and means securing each block to but slightly spaced from each adjoining block, to form a mat, said blocks being disposed in lines and rows arranged each at an angle to the direction of stream flow. f Y
3. A flexible revetment mat comprising a plu'-` rality of slightly spaced blocks arranged in rows disposed angularly with respect to the stream now, whereby the intervening spacesI between the blocks will form no continuous line parallel to the stream flow, and thus no erosion will occur in such spaces, and means on each block directlyinterengaged with similar means on eachadjacent surrounding block to positively interconnect to anchor each block in spaced relation directly to all the adjacent surrounding blocks, thus forming .af flexible, integrate mat extending continuously-.over any desired area, and conforming closely'to the stream bed contour.
-- jThegcornbination of claim 4, in which the blocks are disposedin rows with their diagonals substantially parallelto the stream flow, the spacing lines running angularly to the stream now, so that no such line is presented parallel to the stream iiow, whereby the stream action will deposit silt toI iill the spaces between the blocks,
binding them Y all together into a continuous blanket molded to therprole of the stream bank and bed. Y- I 6. A method of revetting stream banks against erosion which comprises providing elemental concrete blocks each having a connecting member at each extremity, progressively assembling the mat bymutually interconnecting each lblock in? spaced' 'relation to each adjacentY surrounding block by interengagement of the connecting members, progressively laying the mat as rapidly asv formed upon the stream bank; the rows of blocks being disposed so that no continuous line between adjacent rows is parallel to thestream ow, and continuing the assembling and laying vstepsindefinitely to form a single integrate mat of anyv desired extent transversely of or parallel tothe stream flow, flexing as necessary to conform to irregularities in contour and depth of the stream bankandbed. A l lHAROLD O. HOFFARD.