CREST GATE

Abstract: A crest gate for a dam spillway (10) wherein one or more panels (20) are hinged to flexible bladder marginal edge portions (44d) and (44e) so that inflating the bladder (44) causes the panels (20) to move up and hold back water behind the dam. The bladder (44) may itself define the hinge (20a) or the panel (120) may be fabricated from an elastomeric material and itself define the hinge (120a). The airtight seal for the bladder (44) is accomplished by wrapping the marginal edge portions (44d) and (44e) over one another and by securing them with a clamping bar (34).

Description: CREST GATE BACKGROUND OF THE INVENTION This invention relates generally to crest gates for dam spillways and deals more particularly with a crest gate comprising a relatively rigid gate structure that is pivotably provided at the top of the fixed concrete spillwa structure, which gate is movable to a raised position by means of a an inflatable bladder . By way of background a copending application Serial No. 058,837, filed June 5, 1987 and since issued as Patent No. 4,780,024 on October 25, 1988 illustrates such a crest gate construction over which this application dis¬ closes several improvements. The reader is also referred to another copending application Serial No. 215,085 filed July 5, 1988 and to a prior art Japanese patent No. 26108 dated February 16, 19S3. The latter illustrates the crest gate of this general type as well, but the construction disclosed in the Japanese patent suffers from several disadvantages, among them the fact that the gate itself is provided on a conventional hinge. Such a hinge join is susceptible to corrosion as a result of the hostile environment presented by the water be hind the crest gate at least when the crest gate is in its raised condition. Another disadvantage to the prior art Japanese disclosure can be attributed to the configuration for the bladder itself. The bladder is in the form of an extruded member that represents sever problems from a pro¬ duction point of view do the expense of producing such an unconventional cross sectional configuration. One object of the present invention is to provid an improved crest gate configuration wherein the bladder assembly can be fabricated from a single sheet of elas- tomeric material, and wherein the hinge is defined by marginal edge portions of that elastomeric sheet thereby avoiding the need for expensive extruded bladder configura tion and the need for maintaining the integrity of a conve tional hinge joint. Another object of the present inventi is to provide for retaining the bladder in place not only means of anchor bolts or the like adjacent to the hinge li defined by the elastomeric sheet, but also by reason of a line received in a loop provided for this purpose in the elastomeric sheet on the upstream side of the anchor bolt and opposite the anchor bolt relative to the bladder defi portion of the sheet. SUMMARY OF THE INVENTION In its presently preferred form the crest gate the above-identified copending patent application is pro¬ vided on a dam spillway and includes at least one general rectangular rigid panel, which panel is pivotably support adjacent a first edge for movement between angularly spac positions on an axis adjacent to the spillway. The panel has a free edge portion opposite the pivoted marginal edge that is movable vertically between lowered and raised posi¬ tions by an inflatable elongated bladder. The bladder is formed from a sheet of elastomeric material that serves not only as the bladder but also as the hinge for the panel. Means is provided for clamping the overlayed marginal edge portions of the elastomeric sheet to the spillway so that these marginal edge portions provide a sealed joint extend- ing the length of the bladder. Such means includes a elon¬ gated element of generally cylindrical shape such as the length of rope which has the folded back portion of the elastomeric sheet wrapped therearound in order to securely anchor the bladder defining sheet in place. In an alter- native construction the panel is formed from an elastomeric material and has stiffeners or stays inserted in pockets to provide a desired bending stiffness. In this version the panel may define the hinge. While conventional means may be provided for seal ing the sheet at the ends of the elongated bladder so that the bladder can be inflated into position as described, the present invention further includes end fairings adjacent th dam spillway side walls which define a well or wells communicating with a trough defined for this purpose in the spillway in order to provide a path for ambient air to reac the backside of the panel when the panel is in its raised condition and a flow of water over the dam might otherwise create cavitation in this area. The elastomeric bladder sheet has its top margin edge folded back on itself and defining a free marginal ed portion that is in turn secured to the panel adjacent its first pivoted edge in order to define means for pivotably supporting the panel on the spillway. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a vertical section through a preferred panel configuration, the bladder, and the hinge joint, wit the bladder illustrated in its inflated condition. Fig. 2 is a view similar to Fig. 1 but illus¬ trating a slightly modified version wherein the panel is also fabricated from an elastomeric material and clamped the elastomeric sheet defining the bladder. Battens are provided in pockets defined for this purpose in this elas tomeric panel sheet. The bladder is shown in an overin¬ flated condition in broken lines-. Fig. 3 is a plan view of the structure illustra in Fig. 2 and illustrates the well defining end fairings provided at the ends of the movable panel structure and a reveals the communication between such wells and the trou defined in dam spillway itself. DETAILED DESCRIPTION Turning now to the drawings in greater detail, a crest gate constructed in accordance with the present inve tion is best suited for use on a dam spillway 10 having a generally horizontally extending upper surface 10a that ma be defined by the concrete spillway itself or by any super structure of this geometry. At least one generally rectangular rigid panel 20 extends across the spillway so as to hold back water behin the dam structure equipped with such a crest gate. Each rectangular panel 20 includes a first marginal edge 20a an has a second marginal edge (not shown) provided in paralle relationship thereto and forming the upper end of the cres gate structure when in a raised condition. Means is provided for pivotably supporting the panel 20 for movement about a horizontally extending axis located generally coincidentally with this first marginal edge 20a, and preferably said means comprises a sheet of elastomeric material having one and another marginal edge portions laid one on top of the other. These marginal edg portions re clamped to provide a sealed joint therebetween As shown the sheet 44 is inflated, and includes a generall semi-circular portion 44a, and generally flat portions 44b and 44c that lie in contact with the concrete spillway sur face 10a and the backside of the panel 20 respectively. I further accordance with the present invention the elasto- eric sheet 44 includes marginal edge portions 44d and 44e laid one on top of the other to provide the sealed joint f the inflatable bladder 44. A clamping bar 34 of rigid material such as steel or the like is provided on top of these marginal edge por¬ tions of the elastomeric sheet 44 and is secured in positi by anchor bolts, one of which is indicated generally at 32 In order to prevent the bladder 44 from slipping out of position between the top 10a of the concrete spillway and the underside of the clamping bar 34 a portion 44f of the sheet is wrapped around an elongated cylindrical such as a rope 99 so as to increase the cross sectional size of the sheet at an upstream portion of the overlapping marginal edge portions thereof. In further accordance with the present invention the elastomeric sheet 44 further includes a top marginal edge portion 44g integrally connected to the portion 44f wrapped around the rope 99 and also connected in turn to t portion 44d lying against the concrete spillway. This marginal edge portion 44g is provided between the clampin bar and the overlapping end portions of the sheet referre to previously and extends upwardly and outwardly beyond t upturned edge 43a of the clamping bar. The free end port of said edge portion 44g is secured to the panel 20 by fasteners as indicated generally at 40. This end portion 44g together with the portion 44e immediately adjacent to i in the sealed joint, cooperate to define a hinge or pivot means for the lower marginal edge portion 20a of the panel 20. As so constructed and arranged this crest gate construction not only obviates the need for a conventional hinge joint in the hostile environment of a dam spillway, but provides a very economical bladder configuration wherei the pivot defining means for the panel comprises overlappin marginal edge portions of the bladder itself, and wherein the bladder comprises an elastomeric sheet rather than having an extruded such as shown in the prior art Japanese reference referred to in the invention background above. Turning next to a detailed description of the embodiment illustrated in Figs. 2 and 3, Fig. 2 shows a dam spillway 110 having a generally horizontally extending uppe surface that includes an upwardly open trough 110a defined either in the concrete spillway itself or at least in struc ture attached to the spillway. Where the crest gate is at- tached to an existing dam spillway it may be desirable to provide additional structure to define such a trough. At least one generally rectangular panel 120 is provided and extends across the spillway as suggested in Fig. 3. More than one such rectangular panel may be pro- vided as indicated in the above mentioned copending appli- cation, since issued as U. S. Patent No. 4,780,024 but for present purposes one such panel 120 will be shown and des¬ cribed. The rectangular panel 120 is preferably fabricat from an elastomeric material similar to that used for fabr cating the bladder 44. However, the elastomeric panel 120 includes pockets 121 which pockets are open to the outer o upper free edge of the generally rectangular panel 120 so to receive elongated stiffener elements or battens 126. T battens or stiffeners 126 are fabricated from either wood metal or other suitably rigid material. The panel 120 is otherwise similar to the panel referred to in the prior copending application Serial No. 215,085 (that is as shown in Fig. 1) save for the fact tha the panel itself is fabricated from an elastomeric materia and can be conveniently clamped by the anchor bolts 32, 32 that also serve to anchor the marginal edge portions of th bladder defining elastomeric sheet 44. As described above means is provided for pivota supporting the panel 120 for movement about a horizontall extending axis located generally coincidentally with a fi marginal edge 120a of the panel 120. Said means pivotabl supporting the panel 120 comprises a sheet of elastomeric material having one and another marginal edge portions la one on top of the other as described previously with refe ence to Fig. 1. Such marginal edge portions are clamped b the anchor bolts 32, 32 in order to provide a sealed joint therebetween. This construction permits the bladder to be inflated, all as described previously with reference to th above-identified copending applications. A clamping bar 1 of rigid material such as steel or the like is provided on top of these marginal edge portions and in fact on top of the free end portion 120b of the elastomeric panel 120 so that the anchor bolts 32, 32 serve not only to secure the bladder marginal edge portions but to also secure the pane 120 in place as well. In order to prevent the bladder 44 from slipping out of position between the top of the spill way and the underside of the marginal edge portion 120b of the panel 120 a portion of the elastomeric sheet A A is wrapped around an elongated cylindrical element such as ro 199 in order to increase the cross sectional size of the r sulting structure at an upstream portion of the overlappin marginal edge portions with the result that pressure exert by the water on the panel 120 and hence on the elastomeric bladder 144 will not pull the bladder out of position. By way of reference it should be noted that the above-identified issued U. S. patent (based upon the copen ding application Serial No. 058,837) shows and describes actual means for inflating the bladder and for controlling the air pressure within the bladder in response to changes in height of the water "head" upstream of the dam spillway and crest gate generally. That is, means is provided for supplying fluid pressure, preferably an air compressor, an including a supply pipe to deliver pressurized air to a manifold and thence to the interior of the ' bladder. A wat level detection device may be provided for regulating the pressure in the supply pipe to activate the crest gate and raise the panel or panels in accordance with certain pre¬ determined parameters such as the height of the water leve behind the dam itself. A supply valve in the line may be coupled to a water level detection device so as to provide for exhausting air from the manifold when the water level drops below a predetermined level. Although not described in that since issued patent I also have found it advan- tageous to provide a detection device adjacent to the bladder and more particularly between the bladder and the underlying spillway structure itself that will be adapted sense bladder position and hence panel elevation position as to afford a convenient means to reduce air pressure to the bladder in the event that the bladder and panel reach unstable position where it might be possible for the pane to exceed a predetermined design maximum elevational angl It has been found that with the crest gate construction d cribed herein care must be taken to avoid excessive panel elevations such that the panel could move out from behind the end portion 134a of the clamping bar 134. Placement of a reed switch in the area indicated generally at 125 in Fig 2 permits sensing of the bladder's position when there is a possibility of collapsed condition for panel 120, such as that depicted in broken lines in Fig. 2. if the panel 120 is raised beyond a predetermined design position relative t the upturned end 134a of clam bar 134. The output from suc a switch can be provided to the above described bladder in¬ flation control circuitry to reduce air pressure in the bladder and alleviate this condition to reduce any possi¬ bility of collapsing the panel. In the embodiments shown I have depicted the pane hinge as defined either by the bladder itself (Fig. 1) or b the panel (Fig. 2). It will be apparent that the Fig. 2 version could be adapted to provide for the self hinge on the bladder as shown in Fig. 1. The panel could still be secured by a projecting edge portion as shown at 120b in Fig. 2 or, if desired, both the panel and the bladder could be fabricated integrally so that the marginal edge 144 of bladder AA defines the edge portion 120b of the panel.

Claims: Cla ims : 1. A crest gate for a dam spillway comprising: at least one rectangular panel of relatively rigi geometry having a first marginal edge and a second margina free edge, means pivotably supporting said panel adjacent sa first edge thereof for movement between angularly spaced positions about an axis generally coincident with said fir marginal edge thereof, elongated inflatable bladder means including at least one elastomeric sheet having one and another margina edge portions laid one above the other and providing a sealed joint extending longitudinally of the bladder, and means for sealing the sheet at the ends of said elongated bladder so that the bladder can be inflated in order to raise said panel free edge to define a panel up position, said elastomeric sheet having one of said marginal edge po tions folded back on itself a second time to define a free marginal edge thereof, and said free marginal edge of said elastomeric sheet being secured to said panel adjacent sai panel first edge to define said means pivotably supporting said panel. 2. The crest gate according to claim 1 further characterized by a clamping bar provided in overlying rela¬ tionship to said elastomeric free end portions and means fo securing said clamping bar to said spillway. 3. The crest gate according to claim 1 further characterized by an inner tube, said elastomeric sheet sur¬ rounding said inner tube and said tube having ends defining said means for sealing the ends of said elongated bladder. 4. The crest gate according to claim 1 wherein said marginal edge portion of said elastomeric sheet folded back on itself further includes a generally cylindrical elongated element having the folded back portion of said elastomeric sheet wrapped therearound. 5. The crest gate according to claim 1 wherein said elastomeric sheet one marginal edge portion is inte¬ grally connected along a line defining portion thereof, sai hinge defining portion further defining said means pivotabl supporting said panel. 6. The crest gate for a dam spillway, and comp ising: at least one generally rectangular panel, said panel having a first marginal edge and a second marginal edge opposite the first, said marginal edges extending across the dam spillway generally perpendicular to the dir ection of flow for the water over the spillway, means pivotably supporting said panel adjacent said first edge for movement of the second marginal edge o the panel between spaced positions and about an axis gen¬ erally coincident with said first marginal edge thereof, elongated inflatable bladder means including at least one elastomeric sheet having one and another margin edge portions laid one generally on top of the other and providing a sealed joint extending longitudinally of and generally parallel to said axis of movement for said gen¬ erally rectangular panel, said panel comprising an elastomeric membrane t includes pockets extending transversely of said elastomer panel between said pivoted and said free marginal edge thereof, and stiffeners provided in said pockets. 7. A crest gate according to claim 6 wherein sai first marginal edge portion of said panel further includes an elastomeric marginal edge portion (120b) provided adja¬ cent to the overlayed marginal edge portions of said bladder. 8. A crest gate according to claim 7 wherein said panel and bladder marginal edge portions further include at least one of said portions being wrapped around a generall cylindrical elongated element to improve the holding power of the anchor bolts and clamping bar on the assembled struc ture . 9. A crest gate for a dam spillway comprising: at least one rectangular panel, means pivotably supporting said panel adjacent a marginal edge thereof, inflatable bladder means including an elastomeric sheet with marginal edge portions, means clamping said marginal edge portions of said sheet, said sheet marginal edge portions including one of said portions folded back on itself, and a cylindrical elongated element (199) wrapped by said one sheet marginal edge portion to hold said bladder in place.

Inventors: OBERMEYER HENRY K, OBERMEYER, HENRY, K.
Applicants: OBERMEYER HENRY K, OBERMEYER, HENRY, K.
Application year: 1988
Main classification: E02B7
IPC codes: E02B7