No abstract

At present the construction of earth dams is widespread in the Soviet Union and abroad. The construction of earth dams contains a number of diverse technological processes (drilling, blasting, and excavating works in pits, transporting the materials from the pits to the dam, and segregating, grading, and compacting the soils) which are united by a common task --the creation of a continuous flow of the materials being placed in the dam.

Transport of materials during construction of =he Nurek dam is effec=ed mainly by motor dump trucks BelAZ-540 and KrAZ-222. At the present time a trial/production conveyor line has been constructed, 4.6 km long and with a belt width of 1200 mm, along which it is proposed to transport nearly 3million m s of gravel from borrow area No. 12 to the dam. The rest of =his material will be hauled mainly by dump trucks BelAZ-540. The operating conditions for these trucks are becoming more complex as =he dam height and the depth of the borrow areas increase. This creates certain characteristics and limitations in the =ravel regimes of motor dump trucks and operation of their power units.In order to optimize the work of assemblies and units along the most heavily loaded ring road from gravel borrow-area No. 9 to the dam, and their working conditions on steep grades, full-scale investigations were carried our on the dump trucks, using special measurinE-recording equipment. An oscillograph K-12-22 was installed, on which the following parameters were registered: Rate of rotation of the diesel shaft, nd; rotational speed of dump truck's front wheel, nw; rate of rotation of secondary shaft of the hydromechanical transmission (HMT), nwg ; No. of the engaged gear of the HMT, Zwg; application of the wheel brakes, hr, h~; application of hydraulic-brake/decelerator, hh; temperature of cooling fluid in engine, =f; temperature of oil at exit point from =he HMT, =~.Experimental =rips were made, hauling gravel from the borrow area along two routes: Along the ring road, with one-way traffic, and along =he left ba~k, with ~wo-way traffic (see Fig. i). Along the firs= route =he loaded BelAZ trucks cross from the left =o the right bank along a bridge specially constructed for the ring road. For 3 km the road has an average grade of 2.6%, and over the last 300 m before =he dam the grade is 9-10%. The 2.7-km leftbank road has an average grade of 5.6%, of which i000 m is graded 8-I1%. Ten cycles of observations were made with a continuous recording of the above-mentioned parameters. The data on travel regimes thus obtained were processed according =o calibration data, applying mathematical statistical methods. The total travel time along =he firs= route was 11% longer than along =he second, =he number of gear changes was 35% greater, but =he proportion of time that the HMT operated in first gear was 16% less than when working along the second route; the maximum temperatures of oil and water were also somewhat less. The analytical data showed that with one-way traffic =he rime per cycle (trip) was practically the same as for two-way traffic. However, taking into account =hat the investigations were conducted in September-October and that during this period =he monthly output of fill totaled 450,000-500,000 m s (maximum, 1 million m3), preference had =o be given =o =he ring route, which has greater possibilities for intensifying materials transport =o the dam.Construction progress of the dam predetermines utilization of travel patterns for mo=D...

Natural Condkions and Characteristics of Hydro Development. The Nurek hydroelectric station* is the fourth hydroelectric station on the Vakhsh River (after the Golovnaya, Perepad, and Tsentral'naya). The site of its dam is located in the Pulisanga canyon of the Vakhsh River. The Vakhsh River is fed by glaciers and snow melt. The drainage area is 30,700 km z and the average runoff is 20.5 km s. The daily discharge ranges from 120 to 3900 mS/ sec. More than I00 m/ilion tons of suspended load pass through the region of the site during the year.The hydro development structures are located in a narrow canyon composed of Cretaceous rocks and represented by a formation of sandstones and s/irstones. The beds have a 30-80 ~ dip toward the upper pool. In some places the rocks are covered with Quaternary deposits 13-20 m thick. The construction site is located/n a zone of magnitude 8 seismic activity. The hydro development consists of an earth darn, spillway structures located on the left bank, and a powerhouse complex on the right bank. The installed capacity of the station is 2700 MW (9 x 300); annual production is 11.2 billion kwh.The dam will create a 10.5-kin s reservoir with a 70-1an backwater; the usable storage of the reservoir is 4.5 kmS; surface area 98 kmZ; annual drawdownis 53m. The dam, with a height of 300 rn, base width of 1440 m, and crest length of 704 m, is being constructed oflocalmaterials, thetotalvolumeoffillis 56 rnillionm s. Thedam ( For the gravel shoulders and rock surcharge stripping is being done by ~KG-4.6 excavators, then final excavation is done by machines to the reek foundation. The deluvium is removed mainly during the construction of the dam and, as a rule, is reworked into the dam shoulders, i.e., is spread there on the gravel layer and compacted. The particle-size distribution of deluvium is the same as the gravel, only with larger inclusions of rock fragments. This necessitates stripping, for which the ~KG-4.6 excavator has to be used on the dam, running it from Rank to flank, although such use of the machine is not profitable and increases the cost of the works.To obtain a smoother dam foundation within the limits of the loam core, the downcut for the core has been designed and is being made in a configuration sim/Iar to a parabola with agope approximating to unity; for this reason the depth of the downeut reached 20 m in some places. At the lower levels, where there were deluvial soils, and also in the river bed, stripping was begun after damming and diverting the water into the first temporary diversion tunnel. At this time approach roads were constructed and drnl~ug operations begun for smooth shearing and loosening of the rooks on the banks from the intermediate elevations of the first line of the dam.Drilling for smooth breaking was carried out from special contour umnels by means of descending and ascending holes up to 40 m long. The distance between holes was 0.7 m. By means of the first massive blast, carried

The site of the Rogun hydroelectric station is located in a deep, difficultly accessible canyon with steep walls. There is access to the site only from the side of the upper pool.The stretch of the site of the hydro development is bounded by the Vakhsh and Karatega Ranges with elevations of 2000-2300 m composed of sandstones and siltstones, The canyon has a U-shaped form with a slope steepness of about 50-55 ~ The stretch is located on a tectonic block bounded on the northwest by the Ionaksh fault and on the southeast by the Gulizindan fault, the distance between which is 1,2-1,5 km, At 400 m above the axls of the dam there are outcrops of Jurassic salt-bearing deposits at a depth of 20 m below the surface, among which is found rock salt.The main structures include: a335-m high earth-rock dam; outlet works, including temporary diversion tunnels routed from the left bank to the right and a right-bank emergency splillway with deep and surface water intakes; structures of the powerhouse complex with an underground powerhouse on the left bank and 500-kV outdoor electrical equipment; structures for protecting the salt from erosion in the dam foundation; structures of the mudflow protection complex on the Obi-Shur ravine.