wa, tedore, saged. He goting the section 3180 ft, the next area coded was the 24% 330 gout lift innsad of the 318 to 24 got it. Since some of the concrete in the tiger was reative y new when secondary coding was stares, the cooling was performed in the cooling cols at eevations 3277.5, 3285.0, 3292.5, and 3300.0 only at the temperature at thermocouple elevation 3268.75 was 60° F. At the same time cooling was performed in the cooling collis at elevations 3247.5, 3256.0, 3262.5, and 3270.0 until the temperature at thermocouce elevation 3258.75 was 55° F. Upon completion of the above-described partial secondary cooking for the 3240 to 3300 grout lift, the 3180 to 3240 lift was cooled to 40° F. This procedure took place in succeeding pairs of lifts. The top half of the upper lift was cooled to 60° F. while the lower half of this lift was being cooled to 55° F. The lower lift was then connected for the second time, cooled to 40° F. and grouted. This sequence was followed up to elevation 3420 where practicable. Some modification was necessary due to topping out of the longitudinal joints of the odd-numbered blocks 7 through 17 at elevation 3375. This change permitted the cooling of all concrete below the top of the longitudinal joints to the required 50° F. temperature after the 3180 to 3240 grout lift was cooled to its final temperature of 40° F. In a similar manner, the cooling in blocks 5, 6, 19, and 21 deviated from the two-step sequence of cooling operations. The cooling in these blocks at 50° F. was accomplished after the 3240 to 3300 grout lift had been cooled to 40° F. The Board of Consultants1 in their report of October 12, 1961, stated: “The cracks described which were not available for inspection by the Board, are undesirable but are not believed to endanger the safety of the structure. Their elimination at the expense of 1 accreciaby increasing abutment stresses above the present specified mit is not justified.” On August 1, 1962, permission was received from the Denver office to extend the initial cooling periods for those lifts at or below elevation 3420, provided that the drop in temperature did not exceed 1° F. per day. Further, the cooling of the upper and lower halves of the 3360 to 3420 grout lift to 60° and 55° F., respectively, was done simultaneously. Final cooling of the 3360 to 3420 grout lift to 50° F. coincided with the cooling of concrete to 50° F. in the high blocks having joints which terminated at elevation 3480. On February 12, 1962, the Denver office requested that a special thermocouple installation be made in block 4-A, at the elevation 3397.5 lift. The thermocouples were located halfway between the elevation 3390 gate chamber gallery and the block 4A-4-B longitudinal contraction joint, and midway between the transverse joints. The purpose of this installation was to provide additional temperature data on the temperature differentials within a lift in order to correlate temperature stress studies with 7-1/2-foot placement lifts. The first thermocouple was placed on top of the lift at elevation 3390 and was taped to a cooling pipe. Thermocouple No. 2 was embedded vertically above thermocouple No. 1 at a distance of 6 inches, and the next seven thermocouples were embedded vertically above No. 2 at 1-foot intervals. Thermocouple No. 9 was placed at the top of the lift at elevation 3397.5. Thermocouples No. 10 through 15, inclusive, were placed at elevation 3390, adjacent to thermocouple No. 1. These five thermocouples were placed in a line normal to the cooling pipe at 6-inch intervals. The distance from the last of these, No. 14, to the next cooling pipe was measured and recorded. Readings on all thermocouples were taken at the time of embedment. For the first 5 days of the initial cooling period, three readings were taken per 24-hour period at about 7- or 8-hour intervals. For the remainder of the initial cooling period, one reading per day was taken. No further readings were taken until final cooling was started in this area. At that time, readings were taken on a twice-a-day schedule for the first 5 days then twice a week until final cooling was completed. No readings were required thereafter. "Glen Canyon Dam Design and Construction Problems," R. E. Davis, J. W. Vanderwilt, J. J. Hammond, E. B. Burwell, Jr., Julian Hinds, October 12, 1961. for 2 or 3 w ent lift appro times a we in the tough cons throughou arous years nch in wi and the made wa most no rose, the d the t 1963 DAM, POWERPLANT, AND APPURTENANT STRUCTURES Other thermocouples were installed in the dam at 30-foot vertical intervals. During initial cooling, readings were taken twice daily for the first 5 days and once daily for the next 7 days. During the interval, until secondary cooling began, readings were taken twice a month. When secondary cooling was started in a grout lift, the thermocouple readings were taken once a week for 2 or 3 weeks and when the temperature in the grout lift approached 40° F. they were taken two or three times a week. About 800 thermocouples were installed in the dam during the placing of mass concrete. Although considerable cracking occurred in the dam blocks throughout 1962, fewer cracks were noted than in previous years. The cracks ranged from 1/16 inch to 1/32 inch in width. Water emitted from most of the cracks, and the lifts were water tested and all cracks which made water were calked with lead wool before grouting. Almost no cracks were noted during 1963. As the dam rose, the blocks became smaller which no doubt reduced the tendency toward cracking. However, in the fall of 1963, a crack was noted near the contact of the concrete and sandstone at the right abutment. The crack started in the rock upstream of the dam, entered the adit at the end of the utility gallery, came out of the adit and continued across the contact of the dam and the rock and continued down the concrete-rock contact to about elevation 3680. Twenty-one holes were drilled from the top of the dam and the utility adit and gallery, elevation 3697.5, to intersect this crack above elevation 3680. The four downstream holes at elevation 3680 lost water near the contact. This crack was grouted early in June of 1964. 185. GROUTING. (a) Diversion Tunnels and Spillways.-Initial drilling and grouting activities consisted of drilling holes through the right diversion tunnel and spillway tunnel linings to grout the voids in the arch between the concrete lining and bedrock (fig. 105). Grouting of these voids was started in November 1958, in the right spillway downstream of station 26+11. The general pattern for locating arch holes consisted, alternately at 10-foot centers, of two holes located 30° right and left of the centerline of the arch and one hole at the centerline of the arch. Some of the 1-1/2-inch pipes embedded in the concrete lining for radial grout holes were used for grouting arch voids, when they fitted the above pattern. The grout was injected at a maximum pressure of 20 pounds per square inch, and no sand was used in the mix. Type II cement from paper bags was used with a water-cement ratio of 1:1 by volume. A circulating line from air-driven 6- by 3-1/2- by 6-inch and 7- by 3- by 10-inch duplex piston-type pumps was used to deliver the grout to the manitold at the collar of the hole where the injection pressure was controlled by valves. A maximum of five grout units were in operation at one time with the fifth unit containing a helical screw-type pump. Later, another screw-type pump was used to replace one of the duplex piston pumps. The mixer was a horizontal cylinder tub with mixer blades rotating around a horizontal axis. The agitator sump was a vertical cylinder tub with baffles; and paddles were attached to a vertical shaft. Both were powered by small air motors. The water meter foot. Telephone of cubic a read to tenths communication was provided between the manifold and pump. Drilling equipment consisted of lightweight air-powered, power-vane diamond drills. Bits were EX size (1-5/16-inch) and both core and plug bits were u sed in the used. Movable jumbos 41-foot-diameter tunnels for drilling and grouting operations. were Radial grouting was started in December 1958, and the french drain was grouted at the upstream portal. Arch void and radial grouting and drilling of drainage holes continued in the right diversion and spillway tunnels through January 1959, when work was suspended in anticipation of diversion of the river through the right diversion tunnel. Closure was completed and the river was diverted through the right diversion tunnel at 7:30 a.m. on February 11, 1959. The following work remained to be done in the right spillway and diversion tunnel at that time: (1) Drilling of 35 radial grout holes between stations 23+95 and 25+79. (2) Drilling of 21 radial grout holes between stations 32+39 and 39+99. (3) Drilling of a few holes to check the adequacy of arch void grouting from station 25+39 to station 24+37 due to omitting radial holes in this Drilling of radial grout holes was started in the left diversion and spillway tunnel in February 1959. Grouting of arch voids and radial grouting continued in the left tunnel until April 7, 1959, when the work was suspended in anticipation of the left diversion tunnel carrying a part of the spring runoff. Pressure in the radial grouting varied from 10 to 100 pounds per square inch, and the water-cement ratio was 5:1 by volume. Arch void grouting was completed by April 1959, but some radial grouting remained to be done. Grouting of voids under the liners and outlet gates in the left diversion tunnel was started in December 1962, and completed under the three liners and gates in January 1963. Drilling and grouting of the remaining radial grout holes were started in the left diversion and spillway tunnel on December 21, 1962, and completed on January 15, 1963. Contraction joints, periphery and cooling pipe in the left diversion tunnel plug section were grouted, and also the periphery of the contractor's access adit. Two drainage holes were drilled. Final closure of the right diversion tunnel was made on January 23, 1963. The contractor's 16-foot plug adjacent to the closure gates was grouted in March. Radial grouting was completed in the backfill section of the right diversion tunnel and contraction joints, and periphery and cooling pipe were grouted in the plug section. The 18-inch bypass pipe through the plug section was plugged with concrete in June. All concrete had been placed in the backfill section of the tunnel by mid-July 1963. Arch void and radial grouting and drilling of 3-inch drainage holes were completed in the right spillway early in June 1964.1 Arch void grouting, radial grouting, and drilling of drain holes were started in August 1963, at the upper end of the left spillway tunnel behind station as completed in 21+40. The rch oid grouting September and the radial grouting nd drilling of drainage holes was completed in October 1963. (b) Stress Relief Joint.-The report of the Board of Consultants, dated May 5, 1960, recommended that be provided for of a suitable instrumentation should movement determining possible future wedge shaped rock mass at the downstream side of the right abutment keyway below elevation 3370. The Op. cit. p. 454. mass was separated from the canyon wall by a stress relief joint, and this joint was designated as joint A. The A-joint was readily accessible for instrumentation in the powerhouse control cable tunnel and along the joint exposure at the surface of the right keyway. Carlson strain meters and a joint meter were installed in the control cable tunnel in February 1961. Small vertical and horizontal movements were recorded but they appeared to be the result of temperature changes. The Consulting Board in its report of October 12, 1961,1 recommended that the measurements be continued. Additional vents to the A-joint were drilled downstream of the A-line above elevation 3174 where there is no concrete to support or hold the rock on the right canyon wall. An NX hole (2-3/8-inch drill size) at powerplant station 4+14 at elevation 3172, drilled on the right canyon wall, showed a grout seam at a depth of 32.6 feet, which is the A-joint. Three additional holes at stations 4+62, 4+14, and 3+64 at about elevation 3196 indicated the depth to the A-joint ranges from 38 to 36 feet. P00 and 8+40 undation. Gr 3078 was rela Diling equipm swered, power va normally used movement. Beginning in February 1961, stress relief joints in the right abutment above elevation 3121.5 were grouted in 7.5-foot lifts as the concrete lifts were placed in the blocks, so as to maintain concrete against the rock being grouted. Grouting was accomplished through 1-inch risers with relief vents just above the top of the next lift to be placed. Vents were washed after being used for grout returns and then utilized as supply holes for ensuing lifts. These grout holes passed through the A-joint in most cases. In November 1961, the surface of the A-joint was exposed in the downstream area above elevation 3260 and, therefore, the stress relief holes no longer intercepted the A-joint with the exception of the vent 10 feet downstream of the dam. As the collars of the stress relief holes were on the surface of the A-joint, there was no grout travel downstream along the joint above elevation 3256. The stress relief joints were grouted to elevation 3496.5 when the final vents at this elevation were grouted in February 1963. (c) Dam Foundation.--Preparations for drilling and grouting B-holes in the dam foundation began on May 12, 1960, when nipples were set between dam axis "Foundation Adequacy and Design Considerations of Glen Canyon Dam," R. E. Davis, J. W. Vanderwilt, J. J. Hammond, E. B. Burwell, Jr., Julian Hinds, May, 1960. DAM, POWERPLANT, AND APPURTENANT STRUCTURES stations 6+00 and 8+40 in the upstream portion of the dam foundation. Grout take in the area below elevation 3078 was relatively small. Drilling equipment consisted of lightweight, air-powered, power-vane diamond drills. The drilling speed normally used was 50 revolutions per inch of forward movement. Standard EX size plug bits were used. a helical The grouting equipment included screw-type pump electrically powered. Mechanical packers were largely used with pneumatic packers available for oversize holes. Cement used was type II in paper bags from the plant in Clarkdale, Ariz. Initial B-hole grouting was confined to blocks 6 and 7. Grouting of these holes, which intersected the bedding plane at elevation 3078, succeeded in confining water leakage to the vicinity of the heel with minor leakage about 200 feet downstream from the heel along the bedding plane. Five holes on 20-foot centers were drilled and grouted downstream of line 8+93 on dam axis station 11+80 to locate the line of flow of water which was leaking on the elevation 3069 bedding plane joint, about 60 feet downstream of line 8+93. The grout in these holes intersected the water from the bedding plane joint as planned. The concentrated flow was then located on the same joint in block 15 some 200 feet downstream of the dam axis. The flow was piped to the drainage gallery in block 14. Progress in B-hole grouting depended on the rate of placement in adjacent low dam blocks. As the dam rose, B-hole grouting was continued in the right and left abutments. The holes averaged 25 feet in depth, the pressure was about 25 to 45 pounds per square inch, and the water-cement ratio 5:1. Drilling and grouting of B-holes in the left abutment was completed in April 1963 and in the right abutment in July 1963. A-hole grouting from the foundation gallery was initiated in November 1961, in blocks 10, 12, and 14. Very little grout was taken at first. The A-holes made water which accumulated gradually as the hole was drilled deeper, indicating the permeability of the sandstone. Hole 45, drilled to a depth of 126 feet, made water at the rate of 8 gallons per minute and a maximum water pressure of 38 pounds per square inch. Water flowed from other holes in comparable quantities. Holes were drilled in 40-foot stages because deeper stages frequently caused oversized holes in which packers could not be seated. Grouted stages of incomplete holes were washed from 6 to 8 hours after grouting to prevent the necessity of redrilling. Holes were grouted in 20-foot stages from 0 to 100-foot depths, in 25- or 30-foot stages between 100 and 150 where d = depth of the packer in rock. A water-cement ratio of 10:1 was used after trying thinner ratios up to 20:1 for deeper stages with no apparent increase in take. Because of water flowing from drilled A-holes, the area between holes 29 and 45 was made a test area to check the feasibility of decreasing the flow of water in the upper stages of holes prior to drilling the lower stages. All holes were drilled and grouted in 40-foot stages before proceeding deeper in any one hole. The holes were drilled and grouted to the same depth according to the method-of-closure sequence, i.e., on 80-, 40-, 20-, and 10-foot centers, respectively. Flow quantities from each hole were measured after drilling and after washing the stages. It appeared when following out this procedure that none of the water was being sealed off by grouting and that the entire depth of the hole, in rock, was making water. The grout curtain between holes 29 and 45 was completed in April 1962. Drainage holes near grout hole 30 were drilled in February 1962, and a measuring device installed with which the pressure and flow could be measured. The flow at first measured from 5 to 8 gallons per minute but dropped to 5 gallons or less within a few weeks. The A-hole grouting program was completed in July 1963. (d) Chemical Grouting Experiment.-At this time the Denver office was formulating a test program of the feasibility and effectiveness of chemical grouting of foundations. Before starting actual insertion of chemical grout, as much information as possible was desired in connection with source of foundation flow, effectiveness of cement grouting, rate of flow, and similar data. Accordingly, the following procedures were suggested and followed: Step 1. Complete A-hole drilling and grouting of the test area between holes 29 and 45, in the stages reported above. Step 2. After completion of above, drill the drain holes in both the foundation and the drainage galleries through the embedded pipes closest to the radial lines through A-holes 30, 37, and 44, to full depth, i.e., 85 feet plus or minus into rock, and record flows daily. Step 3. About 2 weeks after completion of step 2, drill the drain holes in both the foundation and the drainage galleries downstream of A-holes 36 and 38 to full depth and record flows daily. There was also some early concern regarding erosion behavior of the foundation drainage holes. Water flowing from the initially drilled A-holes deposited sand on the gallery floor and gutter when left uncapped for a period of several hours. Therefore, in addition to the water flow data for drainage holes as outlined in steps 2 and 3 above, the volume of sand that was washed or eroded from each of the drainage holes was recorded. All of the above records were reported in the weekly progress report. The sand deposit proved to be negligible. Step 2 was completed in March 1962, and step 3 started immediately. The advisability of using a chemical grout to seal the Navajo sandstone had been considered previously, but inadequate data were available for proper evaluation. Further testing was therefore necessary to determine if chemical grouting would be effective and which chemicals would give the best results. The Bureau did not have the necessary grout injection available personnel to supervise nor equipment performance of the work. Navajo sandstone is composed of fine to medium sized quartz grains with minor amounts of feldspar, which are only poorly to moderately well cemented. Much of it is cemented only at the points of contact between the grains, leaving a fairly high percentage of open and connected voids through which water will pass slowly but through which cement grout will not pass. Contract No. 14-06-D-4470 was negotiated with Halliburton Oil Well Cementing Co. of Duncan, Okla., who was considered the sole source of supply for the work to be performed. Under this contract the one grouting unit and all contractor furnished necessary related equipment, six chemical grouting materials, and the service of two engineers or technicians who were thoroughly familiar with the equipment and materials furnished by the contractor, and who were competent to advise the Bureau as to chemical grouting procedures. The test site selected was the floor of the left spillway approach channel. Agreements were made CONSTRUCTION with the prime contractor for preparing the site, drilling, furnishing operating personnel, water, electricity and air. Items not payable under specifications No. DC-4825 to Merritt-Chapman and Scott were included under an order for changes. The test area was divided into five contiguous subareas, each 15 feet in diameter. The central hole in each subarea was preserved for injecting grout after saturating each area with several thousand gallons of water through the six holes spaced around the perimeter of the test area. The holes were 1-1/2 inches in diameter and 30 feet deep. The tests included use of four chemical grouts, designated for convenience as follows: type A-a resin-type grout with a viscosity of 6 centipoise; type B-a lignin-type grout with a viscosity of 8 centipoise; type C-sodium silicate plus sodium chloride of very low viscosity; and type D-a combination of chemicals that polymerize to produce a stiff gel, viscosity 3 centipoise at 78° F. Injected quantities of grout were negligible. The sandstone refused to accept the chemical grout in quantity. A new test area was therefore prepared and a different source of water was obtained, as it was felt that dissolved solids in the mixing and saturation water were reacting chemically with grout materials. The new water supply was obtained from Merritt-Chapman and Scott's domestic water supply which contained 70 to 80 percent less dissolved solids than the water used in the first series of tests. Water used in the first series was from the same source as that used for concrete. Grouting operations in the new test area were more successful than those in the original area, the penetration into the sandstone of the three chemical grouts, types A, C, and D, being greatly increased. Acceptance by the sandstone of these grouts in decreasing order was type D (5 percent concentration), type A, and type C (10 percent and 11 percent solutions with or without addition of 2 or 2-1/2 percent, respectively, of sodium chloride). Injection of type B grout was not successful due to its immediate reaction with the chemicals of the sandstone which apparently plugged the voids. |