Figure 48. --Deflection measuring equipment assembly for reading station. -Drill and top for NC 2 MICROMETER SUPPORT STEEL FOUR REQUIRED TARGET SUPPORT STEEL TWO REQUIRED TARGET SADDLE BRASS CASTING TWO REQUIRED ·Drill 45° Counterbore for AUBOYS THINK SAFETY UNITED STATES DEPARTMENT OF THE INTERIOR DEFLECTION MEASURING EQUIPMENT ASSEMBLY FOR READING STATION DRAWN.. TRAGEDY:W.C APPROVED. Pipes -3 Equal spaces 212121 Slope 201 Caps Excavation line Drilled hale Min. SECTION B-B Downstream B Fasten pipe to bar 24 Uplift with wire or weld Reinforcing bar with aff-set Grout Typical detail for holding uplift pipe 6 from PIPE SUPPORT DETAIL NOTES Each uplift pipe to be placed as shown with the bottom & inches Vertical and inclined pipes that extend to foundation shall be All pipes are 21⁄2 inch standard black except as otherwise After pipes have been placed, a drawing showing actual details 2-6 or 30 48. Records and Reports. Readings of the instruments embedded in the dam, the anchor bar load cells, the uplift pressure pipes, the drainflow, and measurements on the plumblines are made in accordance with the schedule shown by the designers' operating criteria prepared for the structure.5/ These data are recorded on appropriate data sheets and transmitted as a monthly report to the Denver office. Daily records of air and water temperature, reservoir and tailwater elevations, and any other data that may have an affect on the structural action of the dam, along with comments concerning the operation of the apparatus or the measurements, are included with the report. Measurements of the movement of the deflection targets on the face of the dam and measurements over the system of theodolite piers are made at a less frequent interval than the embedded instrument measurements. The schedule for these triangulation measurements is also indicated by the designers' operating criteria. 5/ These data are recorded on a series of data sheets and transmitted to Denver as they become available. Computing of the dam's deformation is done by punched cards and an electronic computer. Check measurements of embedded instrument cable resistances are made semiannually. The Bourdon-tube pressure gages used for uplift pressure measurements are cleaned and recalibrated annually. As these data become available they are transmitted to Denver with the monthly reports of instrument readings. 5/Designers' Operating Criteria, "Flaming Gorge Dam, Powerplant, and Switchyard, Flaming Gorge Unit, Green Division, Colorado River Storage Project, November 1963 (unpublished). CHAPTER VI. Design-SPILLWAY AND OUTLET WORKS A. Spillway 49. General. In determining the required spillway capacity for Flaming Gorge Dam, a maximum inflow design flood having a peak of 76,000 second-feet and a 15-day volume of 1,084,000 acre-feet was routed through a combined spillway and outlet works, which resulted in a required total capacity of 32,800 second-feet. The reservoir was assumed to be at the top of the gates (elevation 6040) when the flood routing was started. A surcharge of 5 feet was required to pass the peak of the flood. Since the outlet capacity is 4,000 second-feet, the maximum spillway capacity became 28,800 second-feet. Discharges through the powerplant were not used in determining the capacity of the spillway. 50. Selection of Spillway Location. Location of the powerplant at the toe of the dam made it necessary to select a tunnel-type spillway to pass floodwaters. A study was made to try to utilize the saddle area beyond the right abutment of the dam for an open channeltype spillway, but the poor quality of the rock caused abandonment of this scheme. Comparative estimates were made between a tunnel spillway through the right abutment, utilizing the downstream end of the diversion tunnel, and a separate spillway tunnel through the left abutment. The spillway through the left abutment proved more economical because it was shorter in length and also had the advantage of better alinement with the river. The spillway plan and profile are shown on figures 50 and 51. 51. Model Studies. Hydraulic model studies constructed to a scale of 1:36 were conducted to insure satisfactory performance of the spillway approach channel, spillway crest, tunnel, and flip bucket and to determine flow characteristics in the downstream river channel when either the spillway or the outlet works or both were operating. The model spillway approach channel was considerably modified to improve flow conditions. A combination circular pier and angled approach wall on the right side of the spillway entrance reduced the drawdown and improved flow conditions in the right spillway bay. An outward sloping nose on the spillway center pier reduced the water surface contraction in the left spillway bay. The center pier was extended downstream and tapered to eliminate a large fin of water in the tunnel. Pressure measurements and water surface profiles indicated that the spillway ogee and the transition from the rectangular gate section to the circular tunnel were satisfactory. The discharge capacity of the spillway was greater than anticipated; accordingly the crest elevation was raised 1 foot. Flows in the sloping tunnel, vertical bend, and horizontal tunnel were excellent with symmetrical gate operation. Of the five different angles of lift investigated for the flip bucket at the tunnel portal, a 15° angle provided optimum flow conditions in the river channel. Pressures up to 65 feet of water were measured on the invert of the flip bucket. The minimum pressure observed was 8 feet below atmospheric when the spillway is operating at maximum discharge; the tailwater elevation at the powerplant might be lowered as much as 12.5 feet below the normal river elevation for that flow. The extent of riprap protection needed downstream from the powerplant to prevent damage by the river outlet discharges was determined. For additional details of the model studies refer to the referenced laboratory report. 1/ 52. Tunnel and Flip Bucket. The tunnel portion of the spillway, including the outlet structure, has a horizontal length of approximately 600 feet. The converging tube portion of the tunnel, which is inclined 55° with the horizontal, is 316. 4 feet long. The upper half tapers in diameter from 26. 5 to 20. 5 feet and the lower half from 20. 5 to 18. 0 feet. The 18-foot-diameter section remains constant through the 200-foot-radius elbow to the beginning of the flip bucket. The size of the tunnel was designed so that the depth of water anywhere in the tunnel would not exceed three-fourths of the tunnel diameter. For maximum discharge, velocities can be expected to reach 140 feet per second. Based on reservoir operation studies, the occurrence of large spillway discharges would be very infrequent, so riverbed erosion downstream of the dam should be minor. It was therefore decided that no stilling basin or other expensive energy dissipating device would be provided at the downstream end of the spillway. 1/Rhone, T. J., "Hydraulic Model Studies of Flaming Gorge Dam Spillway and Outlet Works," Hydraulic Laboratory Report No. Hyd-531, Bureau of Reclamation, May 28, 1964 (unpublished). |