US2435568A - Method of and means for protecting river banks - Google Patents

Description

Feb. 10, I948 H. N. ANDERSON 2,435,563

METHOD OF AND MEANS FOR PROTECTING RIVER BANKS Filed Dec. 19, 1945 s Sheets-Sheet 1 v I mmvrox. EMAnderaan BY I Feb. 10, 1948; H. N.1IANDEIRS ON 2,435,563

uETnob OF AN!) M ANS FOR PROTECTING RIVER Bums 3 Sheets-Sheet 2 Fiied Dec. 19, 1945 Fel 10, 1948. H. N.YANDERSON v I 23 5 IETHODOF mnxMus FoR' PROTECTING RIVER BANKS Fild 0 0,19, 1945' smuwsmem flTTOR/VEY Patented Feb. 10, 1948 METHOD OF AND MEANS F: PROTECTING RIVER BANK I Her-shell N. Anderson, Washington, D. 0. Application December 19, 1945, Serial No. 636,043

. 9 Claims. (Cl. 61-37) A (Granted under the act of March 3, 1883, as

This invention relates to a method of and a means for protecting the banks of rivers and the waters line or below to a desired point outward, divide themselves into .two major parts- (1) construction of the structure, and (2) placing of that structure over the area where protection is desired. By far the most diflicult and hazardous of these two problems, and which has been no small contributing factor to the failure of the revetments, is the absence of satisfactory plant and methods of sinking.

The amount of ballast which it has been possible in the past to place on mattresses constructed of timber or lighter than water materials has been governed by the buoyancy limitations or capacity of the structure to uniformly float the ballast load. Usually the per foot load placed never exceeded 12 to 16 pounds. This amount is inadequate and in many cases has failed to force the mattress down and hold-it on the bottom. None of the present methods of sinking have proven successful.

In the case of willow or timber mattresses used in the past, there is little reason to believe that the inadequate amount of ballast which could be placed on them before sinking long remained even fairly well distributed. A fair conclusion is that the .ballast usually rolled to low spots in the mattress while it was sinking and in some instances rolled completely off either before or after the structure reached the bottom. There is no reason to believe that casting ballast on after the mattress reached the bottom amounts to more than a wild guess as to where it would land. The failure to retain an evenly distributed ballast load on the outside edge of wooden mattresses has been one of the outstanding contributory causes of failure at that point. This under ballasting unquestionably allows the mattress either to leave the bottom or cling so lightly as to be ineffective in preventing scour. Coupled with this condition the type of wood structures heretofore placed had only limited qualities to aid them in catching and retaining sufllcient silt to force and hold a secure landing until waterlogging reached a point making superimposed weights less necessary.

amended April 30, 1928; 370 O. G. 757) 2 Most types of mattresses previously placed in the Mississippi River have lacked strength, and disintegration and failures have been on a wholesale scale.

The almost prohibitory cost of revetments has not come about from initial unit cost of placement, but rather from failure of the structure to remain in place after sinking and serve the purpose for which placed, thereby necessitating extensive repairs and in many instances complete renewal at intervals of only a few years.

Concrete mattresses have failed chiefly from (a) inability to properly place them, (b) failure to adequately cover the area to be protected, (0) lack of strength in reinforcement, (d) corroding away of reinforcement, (e) damage from sinking operations, (I) poor concrete, and (g) high unit cost. Other mattresses constructed from processed materials have failed from reasons closely related to those causing failure in concrete revetments.

Some of the pointswhich must be recognized are that in the past the time and eflorts of the organization employed in turning out mattresses constructed from processed aggregates and materials, was consumed chiefly in plant and equipment handling, preparatory work, and plant towing and mobilization, leaving only about of the working time for actual mattress production. Couple these non-productive factors with the ne j cessity for maintaining an extremely large staff of highly skilled operators and technicians along with a large labor force, which often cannot be efliciently utilized while under pay, and it is clear that the cost of these revetments will not long let them endure.

As far as I am aware, there has been no satisfactory type of upper bank protection, both from a cost and a material viewpoint. This portion of the revetment usually fails from under scour at or near the upper limits, or from breaks which nsually originate near or at the low water conour.

It has been found that a combination of types of mattress or revetment is necessary to meet the dual requirements peculiar to the underwater portion of the'bank and to those existing above the low water line or upper bank. These requirements, it is believed, can best be met by (a) the use of a wood or timber structure for the underwater portion of the bank, since such materials are readily available in almost limitless quantities, particularly along the lower Mississippi River, at or reasonably near most locations where revetment protection i planned; (11) a specially designed concrete section having its reinforcement welded to similar reinforcement contained in the-underwater wood or timber structure and extending from the underwater structure up the bank to a point where dry working conditions exist, and (c) a special preparation of the remaining portion of the upper bank with reinforcement contained in the underwater and concrete sections running under or through the prepared bank and secured to fastenings, usually large piling driven at the top of the bank,

Recognizing the major problems involved in effecting a satisfactory revetment, the present invention has for its object the provision of a new and novel mattress construction composed of superposed layers of poles or timbers properly tied together and cooperating to form pockets designed to hold ballast. v

It is'a further object to provide a mattress, the materials of which can largely be, obtained in the vicinity of the point of construction, it having been found in practice that various types of available ballast, such as moss, straw, river clay, and similar materials usually obtainable in the vi- "cinity of the project, can be used successfully, thereby efiecting a great reduction in costs of materials, labor and transportation.

It is a further object of the invention to provide a mattress formed of relatively movable sections so connected as to adjust themselves automatically to the contours of the river bed and thereby compensate for and ultimately eliminate the under scouring which has been a frequent objection to mattresses heretofore employed.

A still further object of the invention is to combine with fabricated mattress sections, a new and novel form of concrete section made up of prefabricated slabs and positioned to protect the I bank between the mattresses and points above the normal water level, that portion of the bank above the concrete section being reinforced by an upper bank protector which can be formed of a heavy layer of clay layed directly upon the bank.

A still further object of the invention is to provide a means by which the mattress section, wlnle being constructed, can be mounted on barges or pontoons provided for that purpose and which are employed for the purpose of conveying the formed mattresses to the points where they are to be submerged, and thereafter withdrawn from beneath the properly located mattresses so as to allow them to sink under the weight of their ballast, to the bed of the body of water. I

A still further object is to provide a new and novel method by which the pre-cast sections of the revetment, can be assembled between the bank and the floating mattress section and subsequently partly or entirely submerged by the removal of the pontoon or other floating supports from beneath the mattress sections.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in certain novel details in construction andcombinations of parts and in certain new and novel steps in the method hereinafter more fully described, it being under-stood that changes may be made in the construction of the revetment and in the method oflacing the same and constructing the parts thereof, without departing from the spirit of the invention as claimed.

' In the accompanying drawings, the preferred form of the invention has been shown.

In said drawings,

Figure l is a plan view more or less in diagram of a revetment section properly positioned prior to being submerged.

Figure 2 is a side elevation of said section while still mounted on its supporting pontoons or other buoyant supports. V

Figure 3 is a view similar to Figure 2 with a portion broken away and showing the revetment section after it has been submerged.

Figure 4 isa plan view of a portion vof one of the revetment sections, different parts thereof being shown in different stages of completion.

Figure 5 is an enlarged section taken longitudinally through a portion of one of the mattress units of the revetment sections.

Figure 6 is a side elevation of a portion of one of the mattress units and showing an anchoring leg joined thereto.

Figure '7 is an enlarged side elevation of the connected end-portions of two units of a revetment section and showing them in one of the positions assumed thereby when supported at different angles on the bed of a body of water.

In carrying out the invention, one or more barges l equipped with suitable power winches 2 are moored in any suitable manner to the bank although that is not essential inasmuch as they are securely held in position by the mooring cables 3 or the like.

After these barges have been correctly positioned along lines substantially parallel with the positions to which the revetment sections are to be submerged, a desired number of pontoons 4 are assembled at the downstream side of the barges and joined thereto by pontoon mooring cables 5 connected to and adapted to be actuated by certain of the drums of the power winches 2.

The pontoons are of a length slightly greater than the width of the unit comprising a revetment section and after these pontoons have been drawn up to the moored barges which cooperate to form a pier or platform from which the workmen can operate, a series of foundation poles 6 is laid across one or more of the pontoons separably at intervals of ten feet although obviously these distances can be changed to meet the requirements. These poles are all of the same length and parallel and are placed with their corresponding ends in transverse alignment.

Closely assembled floor poles 1 are then placed on the foundation poles and are fastened thereto by nails or spikes so that a platform structure of predetermined proportions thus is provided.

Where several units are erected on the pontoons, they are positioned with the ends of the foundation poles of each unit abutting the ends ofthe corresponding foundation poles of the next adjoining unit or units.

After the floor poles have been laid and secured, spacer poles 8 are positioned on the floor poles, these being spaced apart preferably'about ten feet and being extended at right angles to the foundation poles. The spacer poles can be held to the floor in any'suitable manner although it is preferred, as shown in Figure 7, to tie them to the floor and foundation poles by-looping the ends of tie rods 9, the loops in at the ends of these rods being extended under the floor and foundation poles and over the adjacent spacer poles. The tie rods are also extended over the floor poles from one unit to the other, thereby to constitute a flexible hinge connection between two units whereby one unit is free to swing upwardly and downwardly relativeto the unit to which it is joined. This will be obvious by referring to Figure 7 of the drawing.

' After the spacer poles have been secured in position, anchor legs I I are fastened tothe foundation poles as indicated at i2 by spikes and by tie rods l3. Drift pins l4 and tie rods l5 or the suitably anchored. as by means of downstream toggle cables 2 I.

like can be used for tying the upper ends of the anchor legs to the spacer poles.

After the foregoing parts have been properly assembledo and secured, filler timbers l6 are placed between and abut against the spacer poles, it being preferred to place them approximately ten feet apart so that the flooring timbers, spacing poles and filler timbers thus cooperate to form rectangular cells or pockets, each of which is approximately ten feet square.

- tween.

After the required number of units have been built and assembled as explained, they will form a mattress of the required length extending the desired distance over the water with its inner or shore end located at a predetermined distance from the shore line.

As heretofore pointed out, the provision of ballast sufficient to cause the mattress to submerge and at the same time so assembled with the timbers as to remain in position thereon indefinitely after the mattress has been submerged, has been a serious problem encountered by persons engaged in constructing and placing revetments. In the present case, however, it is intended to utilize ballasting means which generally is close at hand. It can consist of alternate layers of a mixture of river clay and fibrous materials such as straw, excelsior, or, in fact, anyvegetation which might serve as a binder. Alternate layers of this material and the clay can be deposited in each cell or the ingredients can be thoroughly mixed before being deposited. Under some conditions, it might, be desirable to use other materials for filling the cells. Thereafter the cells are covered with closely assembled cover poles to form a, top deck or floor for each unit. In the drawa series of parallel regularly spaced control timbersl9 is attached to each end portion of each unit so as to be fixed relative thereto. The timbers of each series are extended well beyond the end of the unit to which they are attached and they are so located that when the units are assembled as heretofore described, the control timbers of each unit will extend between the control timbers of the next adjoining unit. See Fignres 3 and 7.

With the various units of each section of the revetment constructed and assembled as described alongside of the working barges l, toggle cables 20 are attached to the upstream sides of the units and extended to certain drums of the power winches 2. Thereafter the pontoons and the connected units mounted thereon are permitted to drift away from the barges l or they are forcibly pulled from the barges until they are The next step in the construction and placement of the section involves the placement of parallel timbers with one end supported by that unit nearest the shore line and the other end bearing upon the bank at a stable portion thereof. These timbers constitute, supports for preformed slabs ofconcrete 23 which hear at their ends on the timbers 22 and bridge the spaces therebe- The shore ends of the timbers 22 can be equipped with loops 22' or the like to which pulling cables or the like (not shown) can be attached at such time as it might be found desirable to withdraw the timbers 22 from beneath the slabs supported thereby.

With the parts assembled and located as explained. the revetment section is ready to be submerged. This is done by taking-up the mooring cables 5 by operation of the winch drums to which they are connected and as a result the pontoons will be successively or simultaneously withdrawn from under the revetment section which, due to its ballast, will settle to the bottom of the body of water. At the same time, the prefabricated section formed o'fthe concrete slabs will swing downwardly so that the upper portion extends upwardly on the bank to a stable portion thereof while the lower portion is submerged and extends to the shore end of the submerged mattress unit.

After said section has been properly placed below the water level as explained, the pontoons,- having been returned to the downstream side of the barges l, are again utilized as supports on which another section can be erected as heretofore explained and after this second section has been produced, the barges are again floated down into position so that said second section can be submerged and lapped on the previously laid section. This operation is continued until a desired number of sections have been placed in position beneath the surface of the body of water.

prefabricated sections of the revetment can be protected further by means of needle piling forced into the bank close to but above the prefabricated section of concrete slabs and over this section of the bank containing the needle piling, there can be laid a thickness of river clay or the like with or without a binder and which will lead to th adjacent edge of the concrete section.

If desired large anchoring piles can be located adjacent to the top edge of the upper treated portion of the bank and to this anchor piling can be joined reinforcement or the like, extending from the concrete sections.

When each section of the revetment is submerged, the anchor legs II, will be forced downwardly into the bed thereunder, due to the weight of the structure thereabove. Thus danger of the submerged section slipping or sliding out of position is reduced.

An important feature of the invention resides in the fact that each section of the revetment is flexible but at the same time the units thereof are held against lateral displacement relative to each other. This is due to the use of the interfitting series of control timbers. Furthermore, by providing the hinge connections between the units of each section, where necessary, displacement or injury to the submerged section as a result of under scouring is eliminated or greatly reduced. This is due to the fact that as the bed of the body tion, said section will swing downwardly, follow- 7 ing the changing contour of the bed until ultimately the first or possibly the second section will reach a point where further scouring action will be eliminated. In this connection see Figures 3 and 7 of the drawing.

It is to be understood, of course, that many variations in the means of assembling the parts, holding them properly joined while still maintaining the flexibility of the section, can be utilized within the scope of the present invention and while the structure illustrated and the method disclosed are applicable primarily for' use in the protection of the banks of rivers. it is to be understood that the same means and methods can be utiliaed'in the construction of sea walls and in the protection of shore lines wherever it is found necessary to resist erosion resulting from the movement of a body of water.

Obviously any suitable means can be employed for uncoupling th toggle cables from the mattuminous or asphaltic preparation. The reinforcement can be of suflicient sections to withstand corroding over a long period. However failures in reinforcement in the past have not been due to 1 corrosion but rather to lack of strength.

i The cost of the preparation of the upper bank as described will be only a small fraction of that which other protection cost and will be far more eilective.

Negligible critical materials are required for construction andpiacing.

the past when failures and replacement are taken into account.

The necessity for shipping in or manufacturing ballast is not always necessary, thereby dispensing with much floating plant and equipment and 1abor. Materials required for construction are usually readily available in great quantities and the method used for construction requires the minimum of labor, plant and equipment.

The mattress, however, may be ballasted with any desired materials such as stone, concrete or asphalt, as before explained.

- Ballasting is not limited to the buoyancy of the mattress, therefore the structure may be uniformly and adequately ballasted.

With this construction and the described method, there is absolute assurance that the ballast will remain uniformly distributed and that the mattress will collect additional matter after placement is effected.

The mattress can be made strong enough to withstand, and can be placed accurately, under extremely severe conditions.

under the mat and retard the lower or downstream side and forces a more even and uniform rate of sinking and allows the pontoons to be recovered to the starting position. A

The. built up concrete section, which joins to the underwater mattress, affords full protection aginst scour since this section is packed with river claypontaining an effective binder.

All or any specific unit or units of any part of The plan of launching, placing or sinking diffe'rs from any known method in that the pontoon or pontoons are pulled from underthe mattress instead of moving the mattress of! the pontoons. This method has the distinct advantage over other-methods in that the object may be constructed at or over an exact predetermined area and launched with great ease, accuracy, and

safety. Furthermore, the pontoon and mooringset-up can be laid out to accommodate any sizes and/or shapes of mattress and can be used as .a vehicle for launching placing or sinking mattresses constructed of concrete, asphalt, wood, or

other processed aggregates and materials. I

The invention is important because it'requires far less marine plant and equipment than necessary for other methods, can be operated and maintained with a minimum of skilled forces, re-

- quires a minimum of capacity and time to tow from one location to another, and is extremely easy to set up for operations.

The invention described hereinmay be manufactured and. used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. The herein described method of revetment construction and placement which includes the step of positioning a floating structure on a body ofwater adjacent to the banks beside said body, erecting on said floating structure a cellular mat, filling the cells of the mat with suiiicient ballast to overcome the natural buoyancy of the mat, floating the structure and the supported ballasted matto a predetermined range, anchoringthe mat against movement out of position when at the range, positioning a prefabricated section with one end upon the bank and the other end upon the mat, said section being heavier than water, and subsequently withdrawing the floating structures from beneath the mat to release the mat and the prefabricated section for gravitation to the bottom of the body of water thereunder, and finally applying a coating of weather resisting material to the surface of the bani; above the prefabricated section.

2. A revetment section including a hingedly connected cellular unit positioned one against the other, ballast carried by each unit and of a weight suflicient to overcome the natural buoyancy. of the unit, and anchor legs depending from and fixedly joined to the units, the weight of the units being such as to hold the legs embedded in the bed of a body of water in which the revetment is located.

3. A revetment section including hingedly connected units having cells, anchoring legs depending from and fixed relative to the units, ballast supported by the units and of a weight sufllcient to overcome the natural buoyancy of the units. means for holding the ballast to the units, members extending from and supported at one end V on the members and or 4. A revetment section comprising hingedly connected. interfltting units, means carried by the units for anchoring them to the bed of a body of water in which the section is submerged,

a for gravitation of said section to the bed of the body of Water.

8. The method of revetment placement in a body of water having a positive current flow comprising the steps of floating to a predetermined range in said body oi water a series of members bearing at one end upon one of the units and of a length suflicient to engage the bank beside a body of water in which the units are submerged, slabs of prefabricated material supported by the members and of a material heavier than water, and a water resisting coating material extending beyond those ends of the members in engagement with the bank.

5. A revetment section to be submerged in a body of water,. said section including interfltting hingedly connected cellular units, anchoring means' depending from. the units, and ballast carried by the units and of a weight sufllcient to submerge the units and force the anchoring means into the bed of the body of water when the section is submerged.

6. The method of revetment construction and placement in a body of water having a positive flow of current comprising the steps of positioning a plurality of floating elements in parallel relationship to each other in the body of water, erecting on and transversely of the floating elements a series of hingedly connected timber mat units with projecting timbers of adjacent units interfltting with each other, filling the units with sufficient ballast to overcome the natural buoyancy thereof, floating the completed units on the floating elements to a predetermined range, anchoring the units against movement both in the direction 0! and contra to the current flow and thereafter withdrawing the floating elements transversely from beneath the units in the directian opposite to that of the current flow for gravitation of said units to the bed of the body of water.

7. The method of revetment placement in a body of waterhaving a positive current flow comprising the steps of floating to a predetermined range a complete section-of a revetment consisting of hingedly connected, interfltting and ballasted timber mat units mounted transverselyon a plurality of pontoons in parallel arrangement. anchoring the units in the predetermined range against movement both with and contra to the current flow and withdrawing the pontoons transversely from beneath the units in the direction opposite to that of the current flow articulated, lnterfltting and ballasted mat units supported by a plurality of buoyant elements, anchoring said units at the predetermined range against movement both with and contra to the current flow, placing a prefabricated, heavier than water revetment section with one end in interfltting engagement with the terminal mat unit on the buoyant elements and the other end resting upon the shore thereby to bridge the space between the shore and said units and-withdrawing the buoyant elements from beneath the units in the direction contra to the current flow to release the mat units and the prefabricated section for gravitation to the bed of thebody of water.

9. The method of revetment placement in a body of water having a positive current flow comprising the steps of floating to a predetermined range in said body of water a complete section of a revetment consisting of articulated, interfltting and ballasted mat units provided with flxed anchoring legsprojecting from the bottom of said units, said section supported by a plurality of buoyant elements arranged in parallel between said projecting anchor legs, anchoring the said units at the predetermined range against movement both with and contra to the current flow, placing a prefabricated, heavier than water mat section with one end in interfltting engagement with the terminal that unit on the buoyant elements and the other end resting upon the shore thereby to bridge the space between the shore and said units and withdrawing the buoyant elements from beneath the mat units in the direction contra to the current flow to release the mat units and the prefabricated section for gravitating and anchoring to the bottom of the body of water.

. HERSHELL N. ANDERSON.

REFERENCES CITED The following references are of record in the flle of this patent;

UNITED STATES PATENTS Scott Aug. 24. 1928

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