US2529141A - Spillway installation for dams - Google Patents

Description

Nov. 7, 1950 P. F. DANEL 2,529,141

SPILLWAY INSTALLATION FOR DAMS Filed July 5, 1947 3 Sheets-Sheet 1 \NVENTOR Pierre Ffian/Z BY H! I fil'TORNEY P. F. DANEL SPILLWAY INSTALLATION FOR Nov. 7, 1950 DAMS d July 5, 1947 I mvemmz flkrrz F1711!!! 9? TT RN Y NOV. 1950 P. F. DANEL SPILLWAY INSTALLATION FOR DAMS 3 Sheets-Sheet 5 Filed July 5, 1947 R O T N E V m Farm f'fland BY C ATTORNEY Patented Nov. 7, 1950 SPILLWAY INSTALLATION FOR DAMS Pierre F. Danel, Grenoble, France, assignor to Ateliers Neyret-Beylier & Piccard-Pictet, Greoration .of the French Renoble, France, a corp public Application July 5, 1947, Serial No. 759,187

In France July 5, 1946 Claims. (01. 61-18) The present invention relates to improvements in spillway installations for controlling the discharge of flood waters over dam or weir structures.

In the prior practice of discharging flood waters through spillways formed at or adjacent the top of :a dam structure so that the water is permitted to flow down over the downstream side of the face of the dam, it has been customary to mount sluice gates of the sector type above the spillway for rotation about a point of support toward and away from the sill portionof the spillway at or adjacent the highest point thereof.

:Because of the necessity for arranging the point of support of the sluice gate and its operating mechanism outside the path of flow of the discharging stream, according to one prior method shown in Fig.- l, the gate has been mounted for movement about a'pivot located directly above the spillway. As shown, when the gate is in closed position its face is inclined inwardly at a substantial angle. Consequently, it must have a substantially larger expanse than the cross section of the overflowing stream even when the latter is at its maximum flow.

In order to reduce the size of the gateand also lessen the power demand for operating it, it has been proposed to associate the gate with a separate structure supported above the dam structure, such as shown in Fig. 2, which serves as a stationary barrier and cooperates with the pivoted gate on the upper side of the spillway. While the arrangement of Fig. Z'brings about some reduction in the cost of the gate and its operation, both this arrangement and that of Fig. 1 suffer from the drawback that even reasonably satisfactory flo w characteristics are notas sured unless the spillway sill is extendedinwardly from the upstream face of the dam so as to make it possible to give the sill a surface contour favorable to smooth and non-turbulent flow of the nappe over it and down the outer face of the dam. The extension of the lip of the spillway inwardly, as shown, involves a considerable item of added expense when constructing large dams for hydroelectric and flood control purposes to which the invention is particularly adapted.

Even when the spillway sill contour is modified by providing an inwardly extending lip portion as shown in Figs. 1 and 2, there still remains a tendency for the nappe not to adhere continuously and smoothly to the outer wall surface of the dam. When the gat is'not operated until a substantial head of water is built up, this tendency will beincreased and the watermay spurt It is a further object of the invention torea'liae.

the above advantages without resort tothe expensive overhanging lip construction employed in the prior art installation; v

These and other obj ectsi and advantages are achieved according to my invention by providing a spillway in the form of an outwardlyand down:-

wardly curved passage, the upper and'lower walls of which converge for a-distance'from' the en-- trance end and eventually become substantially parallel. The form of the passage may alsovbe compared to that of a curved tuyre when viewedin cross section. The lower wall of: thepassage determines the water overflow level for the "dam and includes a streamlined sill which may be of greater or lesser curvature depending on the volume of water that is to be permitted to .become impounded above the overflow level and upon the inclination of th outer downstream wall surface of the dam, and is characterized by. a smoothly curved outwardly and downwardly. inclined surface which merges into the outer wall of the dam. The upper wall of the'passage may be formed by an upward extension-of the massive structure of the dam or by-any suitable structure supported on the -dam structure in spaced relation to the curved sill. *This upper wall is likewise smoothly curved outwardlyand downwardly and extends downwardly at least substantially to the horizontal plane intersected by the crest portion of the sill and may'continue' somewhat below that plane. spacing of this upper wall from th lower wall are so determined as to insure that the water in traveling through th passage shall have become changed in its direction of fiow so that as it exits from the passage it is traveling downwardly in a direction parallel to and in direct contact onv the one side with the downstream wall surface of the dam that functions as a continuation of the spillway. A sluice gate is placed at or ad-.

jacent the "discharge end of the downwardly directed passage.

Because of the known characteristic-of a nappe The curvature and to contract as it descends from the crest of a weir or spillway, the cross section of the passage at the'discharge end thereof may be very much reduced and, as a consequence, the sluice gate may be correspondingly reduced in size.

The invention will be more particularly set forth and described with referenc to the. accompanying drawings, in which:

Figs. 1 and 2 are Vertical sections of the spillway constructions of the prior art that have been mentioned above;

Fig. 3 is a vertical section of a dam structure to which the present invention has been applied;

Fig. 4 is a vertical section of a dam structure embodying a modified form of the invention; and

Fig. 5 is a vertical section of a dam structure to which still another modification of the invention has been applied.

As shown in Fig. 3, the invention is applied to a dam ID by providing at the crest of the main supporting wall of the dam a rounded sill and associating therewith a streamlined wall section 12 which extends on its inner side upward- 1y to a point above the maximum water level [3 and is curved outwardly and downwardly from a point IE to the point l6 where it assumes a direction substantially parallel with the downstream face I! of the dam. The wall section I2 is supported in part directly on the main supporting wall of the dam, partly by means ofthe spaced piers l8 and partly by the supporting buttresses H) which are shown as disposed in alinement with the piers l8 and as carried by and merging into the downstream side wall of the dam. As further shown in Fig. 3, the superimposed structure may also include an outer wall 20. and a .wall 2| connecting the walls [2 and adjacent posed structure and connected to the gate'by means of a cable 26 attached to the gate at 21: and running over a pulley 28.

In the modification of Fig. 4, the superimposed structure is shown asv a solid massive, but in respect of the contours of the opposed side walls; of the superimposed structure and the sill the arrangement is similar to that of Fig. 3. In this case,-however; the sluice gate is provided with operating motors l l which are carried withinthegate itself and these are connected to jack rods 29 secured to andbearing againstthe side wall of the dam or preferably against pillars thereof extending upwardly between theadjacent spillway passages. v

. Sluice gates of the hollowsector type-are preferably employed because they have the advantage over other types that they do not require the provision of guiding slots or grooves which The sluice gate 22- is pivotally supported at 23 and is operated by a motor 24 and awin'ding. drum 25 housed within the superim give rise to more or less leakage that under some hood 30 supported upon the dam in any suitable,

way, not shown. As shown, the hood extends considerably above the maximum water level for a portion of its extent and thus cooperates with v the rounded sill H" of the dam to form a passage that is quite similar to that of a Syphon, with this difference; however, that there" is no 4 possibility of stoppage of flow due to loss of priming as is the case with a syphon. A construction such as shown in Fig. 5 has the advantage that it does not require any cutting away of the dam structure. g

It will be understood that the superimposed structure plays an important role in directing the nappe downwardly and causing it to flow upon and along the downstream face of the dam. In fact, in the embodiments of the invention shown in the drawings, the upper wall of the spillway passage is so shaped as positively to depress the overflowing sheet of water to some extent and when the overlying wall is continued in this manner to a point at least approximately opposite the point of merger of the sill with the outer side wall v of the dam, and is so shaped in the terminal portion thereof as to direct the nappe in a direction substantially parallel to the downstream face of the dam, it serves to suppress entirely any tendency of the nappe to move away from the dam surface.

Although the nappe does not attain its maxie mum contraction until it reaches the foot ofthe dam, it has been found that the tendency to further contraction becomes feeble beyond the point of discharge from the spillway passage when it is constructed in the manner above dee scribed. Therefore, by. placing the sluice gate at or below the point where the spillway silljhas merged with the downstreamiace of the dam, the practical maximum reduction in the size of the sluice gate for a given volume of discharge is insured. Since the size of the sluice gate and the length of the upper wall of the spillway passage are factors which enter into the cost of the dam, it will be understood that from the cost standpoint the optimum position for the sluice gate will be at or around, and preferably slightly below, the intersection or point of merger of the sill with the downstream side wall of the dam, assuming, of course, that the upper wall of the spillway passage opposite and im- 'mediately above this point has been so shaped as to insure the desired orientation of the-descending nappe slightly toward or at least parallel with the downstream side wall. 7

Economies in construction cost and in operating expense are achieved from the above arrangement even thoughrthe sluice gate is subjected to a somewhat higher head during periods when itis completely or partly closed.

The advantages of smooth flow and continuous adherence of the nappe to the downstrearn side wall of the dam with suppression of tendencies to erosion are realized even under conditions of operation whenthe sluice gate is only partially open for example, as in Fig. 4. The invention has the further advantage that the desired smooth flow and adherence of the nappe may be brought about even under conditions of low head and when the streamlining of the spillway sill is not adapted by itself to: insure that the water in flowing thereover in the form of a thin sheet will pass onto" and along the downstream facing of the dam as a continuous adhering sheet. .In such conditions, the desired discharge -of the water onto and along the: facing of the dam: may be assured by closing the sluice gate to thedesired extent.

The structural arrangements of the present invention have the further advantage} as con trasted with the prior constructions employing sluice gates operating at the upstream level; that bodies floatingon thesurfaceof the water are intercepted by the solid structure in a zone where the flow velocities are low,-and, if desired, a small auxiliary outlet may be provided toward which the bodies are directed along the face of the solid structure.

When the superimposed structure is built into the dam, as, for example, in the forms of Figs. 3 and 4, it may be made to play the role of supporting beams of the buttress type imparting structural strength to the dam.

It will be understood that the invention may be applied in various ways other than those illustrated and that various changes may be made in the details of the construction and in the arrangements of the related elements without departing from the invention which is not to be deemed as limited otherwise than as indicated by the language of the appended claims.

I claim:

1. In a spillway installation for dams wherein the downstream face of the dam is inclined outwardly and downwardly to provide an extended spillway surface freely open to the atmosphere at least along the lower portions thereof, the improvement which includes an outwardly and downwardly inclined sill which merges in the form of a smooth curve into the downstream face of the dam, means positioned above and in spaced relation to the sill for directing water overflowing said sill downwardly in a direction substantially parallel to the downstream face of said dam and in contact therewith, and a sluice gate movable toward and away from the downstream face of said dam across the orifice defined between said means and the downstream face of said dam,

2. In a spillway installation for dams wherein the downstream face of the dam is inclined outwardly and downwardly to provide an extended spillway surface freely open to the atmosphere at least along the lower portions thereof, the improvement which includes an outwardly and downwardly inclined sill which merges in the form of a smooth curve into the downstream face of the dam, means positioned above and in spaced relation to said sill and defining therebetween an outwardly and downwardly. extending streamlined passage for water overflowing said sill, said passage in the lower portion thereof being substantially parallel and in line with the downstream face of said dam and being of substantially reduced cross-section as compared with the portion adjacent the top of said sill, and a sluice gate movable toward and away from the downstream face of said dam across said passage in the portion thereof of reduced cross-section.

3. In a spillway installation for dams wherein the downstream face of the dam is inclined outwardly and downwardly to provide an extended spillway surface, the improvement which includes a spillway defined by an outwardly and downwardly inclined sill which merges in the form of a smooth curve into the downstream face of the dam, a barrier disposed above and in spaced relation to said sill and defining between said sill and said barrier an outwardly and downwardly extending passage through which flood waters are guided in a direction paralleling and in contact with the downstream face of said dam, said barrier including a wall portion extending in spaced relation to the outer wall of said sill to a point at least opposite the point of merger of said sill with the downstream face of said dam but terminating a substantial distance above the foot of said dam, and said wall portion in the lower part thereof also extending in a plane substantially parallel to the plane of the downstream face of said dam, and a sluice gate mounted adjacent the lower end of said passage for pivotal movement toward and away from the outer wall of said dam for controlling the fiow of Water past said spillway.

4. In a spillway installation for dams wherein the downstream face of the dam is inclined outwardly and downwardly to provide an extended spillway surface, the improvement which includes an extension of the dam structure to a height above the maximum water level under flood conditions, the provision in the dam face beneath the crest of the dam of a smoothly curved spillway passage extending outwardly and downwardly to a point below the sill portion of said spillway but terminating a substantial distance above the foot of said dam, said passageway being defined on the upper, outer side thereof by a smoothly curvedwall portion which gradually converges toward the inner wall portion until it assumes a position approximately parallel with the inner wall at the level of the sill and then continues for a short distance downwardly in parallel relation to the downstream face of the dam, and a sluice gate of the sector type mounted adjacent the lower end of said passage on a pivot supported outside the line of flow.through said passage for movement toward and away from the downstream face of the dam for controlling the flow of water past said spillway and causing the water when it is discharged in the form of a restricted flow to travel downwardly along the downstream face of said dam.

5. The improvement in spillway installations according to claim 1, wherein the operating mechanism for the gate includes jack rods bearing against the downstream face of the dam operated by motive mechanism housed within the sluice gate.

PIERRE F. DANEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,741,320 Lee Dec. 31, 1929 FOREIGN PATENTS Number Country Date 364,960 Germany 1922 488,343 Germany 1929 800,757 France 1936

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