US 2949743 A
Description (OCR text may contain errors)
2 sheets-snet 1 INVENTOR.
ATTORN E Y Aug. 23, 1960 F. w. scHElDENl-IELM DAM AND METHOD oF MAKING 'rma SAME Filed Nev. 13, 1957 FREDERICK w. scHExDENHELM E mzoN WNMINIIMHIWUIHIIIIHI d \\,...Hlll|lll Il Hhllllli n..JHHIHWMIMIHWIHINWHINIH n w19 .u..DWMMIWMIMMIHIHIMMINIWW .Vll olh. llllll Il IIIIIIIIIIIHIIIHIHIH .VHHHHHIHHHHHHHHHHHNHHNHHHMNIHIHIHIHI .E wzoN S;
A118-v 23, 1960 F. w. scHr-:IDENHELM 2,949,743
DAM AMD METHOD oF MAKING THD SAME 2 Sheets-Sheet 42 Filed Nov. 13, 1957 INVENTOR. DERICK W. SCHEIDENHELM yf/ AAM ATTORNEY H wzoN K. .l |||F A AA'V 1 l |ll||| uw,... MMMMM wir l A\ m AIM. MMIWHHM nited States Patent Frederick W. Schedenhelm, Kew Gardens, N.Y.; Jean- Wolif, executrix of said Frederick. W. Scheidenhelm, deceased Filed Nov. 13, 1957, Sen'No. 696,105 4 Claims. (Cl. '6l-30) This invention relates to the art of structures, such as dams, which are to be subjected to the pressure of a body of water. The invention pertains, more particularly, `to constructions embodying such structures and to the method of making the same.
The primary object of the invention is -to provide an improved rock fill dam which, in actual use, has afforded and, in prospective uses, will aiord substantial economies compared with known rock fill dams.
Another object of the invention is to provide a dam or similar structure having improved and simplified features of construction.
A further object is the provision of a dumped rock ll dam characterized by a substantially Water impermeable and flexible deck consisting only of asphaltic concrete which is disposed directly on the upstream face of the rock fill.
It must be borne in mind that a dam, the body of which is comprised solely of rock ll, requires a diaphragm or membrane which covers the upstream face of the rock fill and which is hereinafter referred to as a deck It has been ascertained that, in the construction of a dam of this invention, it is not necessary to use any material other than rock and asphaltic concrete, together with, if circumstances require, a relatively minor amount of asphaltic cement or some other suitable binder.
The rock required yfor the dam yof this invention is preponderantly such as constitutes the gross product of quarrying and consists to only a minor extent of rock or stone which has been submitted to the mechanical process of crushing. Moreover, the rock is placed by the simple and least costly process of dumping from automotive trucks, skips manipulated by derrick or cableway, conveyor belts or any other suitable means. Only a minor amount of spreading is required even for the upstream surface portion of the rock lill, so that that ll may serve as a base, as hereinafter described.
One of the important features of the invention is that there is not required the customary placing by hand, or by derricks, cranes or other mechanical means, of selected rocks in the upstream portion of the rock fil-l in order that the latter may be adapted to the superposing of the deck thereon. Herein lies a major economy resulting from this new type of rock fill dam, especially as compared with the customary type, which uses a deck made of Portland cement concrete, whether plain or reinforced, for the reason that the latter type is usually, and as a matter of practical necessity, provided with a planar and sloping base of generally large, carefully placed rocks or stones upon which such a deck is formed.
inasmuch as the function of the deck of a rock lill dam is to impound water, it must be watertight, i.e., impervious or impermeable to water. In addition, the deck needs to be sufficiently flexible to be self-adjusting to the settlement which normally occurs in any rock ll dam. Also, the deck should be constructed of a material which is durable and such that the construction may be rapid and that any requisite repair of the deck may be made without undue difficulty.
For the construction of such a deck, the present invention utilizes only asphaltic concrete. By asphaltic concrete is meant an appropriate mixture of asphalt, coarse stone aggregate (of size such as is used in Portland cement concrete) and fines (of stone or suitable earthly materials). The asphaltic concrete is placed in the form of a pavement comprised of one or more relatively superposed layers, the asphaltic concrete generally being hot when placed.
The customary rock fill dam having a deck made of Portland cement concrete, Whether plain or reinforced and whether or not constructed in blocks or panels, does not afford all of the above-mentioned requirements and desiderata. In summary and in contra-distinction to the customary rock fill dam, the dam of this invention, by virtue of having a deck made of asphaltic concrete, affords another major saving of cost.
In the interest of maximum economy and because the rock comprising the fill, Iwhen dumped as indicated above, disposes itself naturally on a slope, the upstream surface of the rock ll, upon which the deck is to be superposed, must necessarily have a slope not steeper than the natural slope of the dumped rock (generally about 1 vertical on 1.3 to 1.4 horizontal). In this respect, the practical aspects of placement of the asphaltic concrete deck pose no difficulty, for they make it desirable to use a somewhat flatter slope, usually not steeper than 1 vertical on 1.5 horizontal.
It has been found that, in order lto attain the greatest saving which may be realized from the dam of this invention, the placement of the asphaltic concrete to form the deck should, so far as feasible, be accomplished by means of paving machinery and other equipment which are of standard manufacture and used extensively in the construction of asphaltic concrete surfaces of highways and of airplane runways. For this purpose, the upstream portion of the rock fill is so prepared that it will be stable and immobile under the movement thereon of loaded trucks and of hea'vy paving equipment, i.e., the objective is that lthe use of such equipment will result in a minimum of disturbance or roughening of or undulations in the surface of said upstream portion.
It has been found that such stability and immobility in turn are attained by this new form of construction of the rock ll and in particular of the upstream surface thereof.
The enumerated objects, together with the advantages attainable by the practice of this invention, will be readily understood by persons skilled in the art from the following detailed description and the accompanying drawings, which, respectively, describe and illustrate a preferred embodiment of the invention.
In the drawings, wherein like reference characters denote corresponding parts in the several views:
Fig. l is a View, partly diagrammatic and partly in transverse cross section, of a dam constructed in accordance with this invention; and
Fig. 2 corresponds to Fig. 1 and is an enlarged view of an upstream portion of the dam.
Referring initially to Fig. l, the dam illustrated therein comprises a base consisting essentially of rock iill which is generally denoted by the letter R. This rock fill, for the purposes of this description, may be considered as being disposed in three zones, namely, zone I, zone II and zone III. The rst two zones comprise preponderantly rocks of large size, while zone III is composed of rocks which are of a smaller size and which in this description and the appended claims are referred to as stones Such rocks and stones are disposed by dumping in contra-distinction to laying or placing by hand or by mechanical equipment, such as derricks, cranes and the like. In the drawings, the rocks of zone tion of liner components of such rock, for the reasonr that, if the smaller pieces and particles lodge between the larger pieces, they are susceptible to crushing under the weight of the rock fill above, with the result that in time# there may be undue settlement within and of the body of the rock fill. Therefore, the material of this first zone preferably contains not more than 10% by weight of pieces and particles less than 4 inches in size.
Zone II lies upstream from and upon zone I and merges into the latter. The rock of zone II is dumped directly upon the naturally assumed 'upstream slope of the rock of zone I. Zone II has the two-fold function of (a) providing what may be termed a transition from zone I to zone III and (b) ensuring free drainage to the bottom or deepest portion of the dam.`
The transition is not made gradually but rather abruptly. The same specification as to size of rock obtains throughout zone Il. The maximum permissible size of the pieces of rock should be materially less than in the case of the zone I. Preferably the preponderant range of sizes of pieces should be from 4 linches to 30 inches. The material should be clean and well graded; the more nearly uniform the gradation, the better.
The object of free drainage is to ensure that there will be no entrapped seepage water which, regardless of source, upon drawing down of the impounded water, might by its pressure in the upstream direction damage the deck of the dam. To insure free drainage, this zone should be devoid of all pieces and particles of rock less than 3-inch size. The system of drainage is completed by providing along the ioor of the valley or the stream bed a reliable means of drainage (not shown) from the upstream side of the rock ll, specifically connecting with the lowest portion of zone II and extending to and through the downstream face or toe of the dam.
The rocks of zone II occupy the space between the upstream slope, gene-rally a natural slope, of zone I and a highly irregular surface which is somewhat short of the lower surface of the asphaltic concrete deck. 'The thickness of this zone may vary but should generally be not less than 5 feet and ordinarily need not be more than l0 feet. The approximate upstream surface defined by the rocks in this zone should be not more than 24 inches, preferably only l2 inches, short of, nor should any part thereof be nearer than 2 inches to, the lower surface of the asphaltic concrete deck.
The rocks comprising zones I and II of the rock till may be angular, but the more rounded the edges of the pieces of rock, the less will be the undesired settlement of the rock iill after completion thereof.
Zone III consists of thoroughly compacted surfacing stones. The function of this zone is to ll the outer or upstream interstices of the rock of zone I-I and to extend such filling outward, to such extend that the outer surface of the zone Ill material has the same configuration, generally approximating a sloping plane, as the lower surface of the asphaltic concrete deck, which rests directly upon such outer surface. In general, the less the thickness of zone III the better.
Zone III is not watertight but rather is free draining to the greatest extent compatible with the attainment of the rigidity and immobility requisite for its service as a surface upon which the deck is placed. The outer interstices of the zone Il rock are Iiilled, not completely or solidly but, only in the sense that the zone III stones are tightly wedged into those interstices.
The requirement of maximum rigidity and immobility makes it preferable, for optimum results, that the surfacing material in zone III be of crushed (hence angular) stones which are sound, hard and within the size limits preferably of 1/2 and 4 inches. The zone III stones should be clean and devoid of pieces and particles of less than the indicated smaller size.
To the end of attaining the stability and rigidity requisite for the placing ofthe asphaltic concrete deck, particularly in the cases of the steeper, deck slopes or of given material comprising; zone III, it may be desirable, or even necessary, to apply to the surface stones a binder in liquid form,.such,as an-appropriate type of asphalt or other suitable material. In` any case, once the material comprising the third Zone` has been dumped and spread, it must be thoroughly compacted, preferably by a process involving vibration.
The cost of preparing .therock till for placement of the asphaltic concrete deck is far less than the cost of preparing the base in the case of the customary type of rock fill dam which has a deck of Portland cement concrete.
As is indicated in the drawings, particularly in Fig. 2, the rocks 2 in the downstream portion of zone II project into the interstices defined by rocks 1 in the upstream portion of zone I. Similarly, downstream stones 3 of zone III are lodged in the interstices defined by the rocksy 2 of the upstream portion of zone Il. From this it is apparent that zone Il merges with zone I while zone III merges with zone II. As is shown in the drawings, there is no clearcut line or surface demarcation between the rocks of zones l and Il or between the rocks of zone II and the stones of zone III. The mean surface of dcmarcation between zones I and Il is represented by dot-- dash line a, while the mean surface of demarcation between zones II and III is represented by dot-dash line b.
The rocks of zones I and Il and the stones of zone III may be placed in vertical stages or lifts, Ias they are referred to in the art. In the cases of dams of relatively great height, the placement of the rocks and stones in lifts is likely to be a matter of practical necessity.
In gener-al, the dam of this invention should embody means for cutting off or preventing seepage from the irnpounded water through the ground or other foundation G upon which the base R rests. Such cut-off means should be at and in downward extension of the approximate intersection of the deck D and the foundation G. In Fig. l there is shown illustratively a cut-off wall C, which may be made of Portland cement concrete, asphaltic concrete or any other material known to the art. In the illustration, the deck D is shown as extending over the top of the cut-olf wall C.
As has been stated earlier herein, deck D consists of only asphaltic concrete which is placed directly on the rigid and immobile upstream surface of zone III. Also, this deck is water impermeable. To obtain the latter property, the asphaltic concrete must be dense. The requisite density is attained by suitable compaction of the asphaltic concrete.
The asphaltic concrete may be placed in one or more layers, the total thickness depending largely upon what will be the overlying depth of impounded water. If the asphaltic concrete is placed in more than one layer, the joints within the upper layers should be staggered or offset in relation to the joints Within any lower layer.
The procedure in placing deck D may, generally speaking, be the same as or similar to that followed in highway paving, with the exception that it may be necessary to rig cables from lthe equipment to Winches or similar means located at a higher level, in order to move the equipment up and down the slope and to do so safely.
From the foregoing, it is believed that the dam or similar structure of this invention and the method of making the same will be readily comprehended by persons skilled in the art, without further description. It is to be borne in mind, however, that various changes in the structure herein shown and described and in the method of practicing the invention, as outlined above, may be resorted to without departing from the spirit of the invention as defined by the `appended claims.
What is claimed is:
1. In a dam or similar structure which is subject to the pressure of a body of water, a base comprising rock ll, said base comprising an upstream zone and a downstream zone, said downstream zone being of greater width than the upstream zone and comprising rocks at least 4 inches in size, said upstream zone consisting of a layer of angular stones which are of a size up to 4 inches and which are substantially immobile relative to each other, and a deck constituting the upstream face of the dam and consisting of a substantially water-impermeable membrane of asphaltic concrete, said deck being disposed directly on the upstream face of `the base.
2. In `a dam or similar structure which is subject to the pressure of a body of water, a base consisting of rock till, said base comprising an upstream zone and a downstream zone, said downstream zone being of greater width than the upstream zone, at least 90% of the downstream zone consisting of rocks at least 4 inches in size, said upstream zone comprising a layer of angular stones which are of a size up to 4 inches and which are substantially immobile relative to each other, and a deck constituting the upstream face of the dam and consisting of a substantially water-impermeable membrane of asphatic concrete, said deck being disposed directly on the upstream face of the base.
3. The method of making a dam or similar structure which is to be subjected to the pressure of a body of water, which comprises forming a rock fill base by the steps of randomly dumping rocks, at least 90% of which are at least 4 inches in size, to obtain the downstream zone of the base and dumping on the upstream face of the downstream zone a layer of angular stones of a size not exceeding 4 inches, compacting said layer whereby to render the stones thereof substantially immobile relative to each other, and forming directly on the upstream face of said layer of stones a substantially water-impermeable membrane consisting of asphaltic concrete.
4. The method of making a dam or similar structure which is to be subjected to the pressure of a body of water, which comprises forming a rock lill base by the steps of randomly dumping rocks, at least of which are at least 4 inches in size, to obtain the downstream zone of the base and dumping on the upstream face of the downstream zone a layer of angular stones of la size not exceeding 4 inches, compacting the layer of stones by subjecting the same to rolling whereby to render the stones thereof substantially immobile relative t0 each other, and forming directly on the upstream face of said layer of stones a substantially water-impermeable membrane consisting of asphaltic concrete.
References Cited in the le of this patent UNITED STATES PATENTS 998,813 Todt July 25, 19'11 1,903,760 Giraud Apr. 18, 1933 2,130,044 Subkow Sept. 13, 1938 FOREIGN PATENTS 92,912 Switzerland Feb. 1, 1922 480,361 Italy Apr. 29, 1953 OTHER REFERENCES Rock Fill Dam, Scientic American, March 1937, pp. 168 and 169.