【正文】 tilt gages on each feed bin。But the fast pace of placement required to achieve the economies possible with RCC imposes a greater discipline (要求)on the planning, scheduling(進度), and coordination(協(xié)調) in the field between designer(設計) and contractor(承包商).The RCC design approaches described in Chaps. 4, 5, and 6 diverge(不同點在于….) in some construction procedures. an electronic water flow meter。 and an 18yd3 (14 m3) twostage surge bin.The plant could be operated manually or by a puter programmed to initiate the production sequence starting at the surge hopper(涌浪式加料斗). Sensing devices included a feedbelt scale（帶稱）。 The construction plant for RCC is usually, less costly, and utilized at a higher capacity factor （利用率）than that required for conventional concrete gravity dams. In all cases, however, the mixing(拌合), transporting(運輸), spreading(攤鋪), and pacting (碾壓)of relatively large volumes of material are concentrated into a short time interval. In the United States, the time limit from mixing plant to final paction is about 45 min. It is about twice that in Japan. In addition, the Japanese RCD method requires that lifts be cured (養(yǎng)護)for as long as 36 h before placement (澆筑)of the next layer of RCC. In the United states and elsewhere, the goal has nearly always been to e as close as possible to continuous placement of RCC. SchedulingConstruction scheduling for RCC is less forgiving than for mass concrete(大體積混凝土). Although some mix designs can have greater tolerances than conventional concrete, RCC is still a sensitive concrete and the critical path (關鍵路線)for placing RCC is focused on pleting one lift at a time. There are no alternate monolithic (整塊的、獨塊的)blocks to form or place while problems are being analyzed.To avoid costly delays over disputes on specification（規(guī)范）pliance（執(zhí)行）, the authority to resolve engineering problems must be vested in a well trained field organization. Lines of munication between the project engineer（項目工程師）and contractor must be clearly established and used frequently. Clarity(廉潔), candor（坦誠）, and cooperation are very important in achieving the speed of placement possible with RCC.Thorough field and classroom training of construction crews（施工隊伍）and inspectors（檢查員） in the handling and placement of RCC is essential. Lean, dry RCC mixes resemble damp（潮濕的） gravel（砂礫石）and are often placed by roadbuilding or earthdam crews using earthmoving equipment. However, all the desired characteristics of the product are those of concrete. Meeting the specifications requires educating workers to the specific requirements of RCC as a new construction material requiring specific construction methods.Because so much depends on fast, efficient placement of the RCC, all related activities such as foundation cleanup, access, assembly of embedded ponents(預埋件), and stockpiling （貯存、堆存）of materials must be meticulously planned and scheduled well before construction starts. Construction of forms and assembly of embedded items should be planned and scheduled so that as much of the work as possible is done off the dam, or if necessary, from the top of a lift （升程）during shift（工作班）changes.Lift scheduling is often plicated by concerns over heat buildup. Because the production rate of RCC can be very high, controls to limit thermal cracking（溫度裂縫）may restrict the season or time of day that placement is allowed as well as the rate of placement.At Upper Stillwater Dam, all of the RCC was placed during a fivemonth weather window each year from May to October and only during two 8h shifts starting at 8 . This was necessary in order to keep placement temperatures below the 50oF (10oC) specification limit. At Willow Creek and Galesville dams, placement was limited to no more than three and four lifts, respectively, each 24 h..Conversely, at Elk Creek and Stagcoach dams, the contractor was encouraged to place RCC as fast as possible. At peak placement, six 1ft () lifts were placed in a day at Stagecoach. The 150fthigh (46m) dam required 44,500 yd3 (34,000 m3) of RCC which was placed during 37 days in the summer of 1988. To keep placement temperatures low at Elk Creek, the specifications required that the most massive sections be constructed during the late winter and early spring. Aggregate Production and Plant Layout (砂石料生產和混凝土工廠布置)Maintaining adequate supplies of acceptable aggregate is particularly important to RCC scheduling. More than half of the aggregate required for an entire construction season may need to be stockpiled well ahead of the start of construction in order to keep up with extraordinarily high demand during the placement season. This can also provide some easing(緩解)of cash flow（現金流）and scheduling requirements during the placement season. Large stockpiles also allow for more economical sizing of production facilities and for blending of material that may be out of specification. If precooling of aggregate is desired to keep placement temperatures low, stockpiling in the winter provides that opportunity.Continuous raw feed to stockpiles is necessary throughout the construction season to keep up with RCC production. At Upper Stillwater Dam, the largest in the United States, the contractor had to produce 9000 tons/day (8160 metric tons) of 3/4 and 2in. (19 to 50mm) aggregate from soft sandstone to keep up with its RCC placement schedule of 7200 yd3/day (5500 m3/day) during the final construction season in 1987.The location, size, and shape of aggregate piles must be coordinated with the concrete plant location and method of feed. If conveyors (傳送帶、皮帶機)are not used, several large loaders may be required to feed the mixers on large RCC projects. To achieve RCC production of 900 yd3/h (690 m3/h), for instance, four 12yd3 (9 m3) frontend loaders could be needed to allow for a reasonable interval between loadings. The haul distances（運距）, dumping procedures（卸料過程）, and turnarounds need to be planned carefully to operate efficiently and safely.At Elk