共查询到20条相似文献，搜索用时 31 毫秒
1.
| 1. |
The installation of a conical transitional segment between a tower (shaft)-type water intake-outlet and penstock affects a significant reduction in head loss in the pump mode, but has virtually no effect on the magnitude of the latter in the pump mode.
| | 2. |
The existence of a conical transitional element in the pump mode appreciably lowers the discharge velocities of the flow and increases the effective height of the water-passing openings by 1.5–1.7 times when the height of the intake openings h0.5dp.
| | 3. |
The head losses in the intake-outlet decrease in the pump mode of operation with increasing degree of expansion of the transitional diffusor segment.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 21–23, November, 1992. 相似文献
2.
Conclusions
| 1. |
During discharge of a flow from a cone valve at small heads E0/hv≤1.2, when the upper part of the jet falls on its lower part, the maximum velocities are observed in the center of the flow,
and when E0/hv>1.2 their maximum values shift toward the side walls, which can lead to erosion of the banks in the lower pool of the structures.
|
| 2. |
Experimental dependences were obtained for determining the conjugate depths in the lower pool beyond the cone valves with
free discharge of the flow into the atmosphere.
|
| 3. |
The proposed efficient structures for dissipating the excess energy of the flow beyond cone valves make it possible to distribute
the unit discharges over the width of the lower pool and to avoid dangerous erosion of the bottom and banks of the river channel.
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Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 7, pp. 28–30, 1997. 相似文献
3.
| 1. |
Tests confirmed the reliability of the work of the reinforced concrete-encased steel design of the link of the penstocks of the Zagorsk pumped-storage station in the range of pressures up toP=1.4 MPa. The lining of the link and hoop reinforcement of the inside and outside rows take the tensile load in the elastic stage.
| | 2. |
The allowable opening of cracks for reinforced concrete-encased designs of a penstock with an inside sealing lining in the range of pressures up to 1.6 MPa with a width of the cracka
c
0.2 mm does not exceed the standard requirements.
| | 3. |
The test of a particular link showed that with loading by an internal pressure the lining takes 30%, the reinforcement of the inside row 23%, and the reinforcement of the outside row 47% of the external load.
| | 4. |
The tests confirmed the complete correspondence of the work of the link to the design data and earlier investigations carried out in a range of pressures exceeding the operating pressure by 30%.
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Deceased. 相似文献
4.
| 1. |
Provision for stability of slopes is one of the main problems in designing plains PSHS.
| | 2. |
The reasons for occurrence and a chain reaction of development of landslide phenomena on the south slope of the area of basic structures of the Zagorsk PSHS were peculiarities of its engineering-geological structure that were not properly taken into account in designing and carrying out construction work.
| | 3. |
For the purpose of stabilizing the landslide slope, a system of engineering measures was developed and implemented, including a change in the configuration and structure of the right-bank abutment of the upper-basin levee to the water intake, construction of a banquette, filling of a counterbanquette, draining of moraine loams, grading of the slope, surface water diversion, and monitoring of the state of the slope and elements of the antilandslide protection.
| | 4. |
Data from full-scale observatins indicate the effectiveness of the antilandslide measures that were performed and a state of the slope corresponding to criteria for the hydro development's safe operation.
| | 5. |
Innovative elements of the system of measures to stabilize the south landslide slope of the Zagorsk PSHS are:
|
| – |
the complex nature of measures, providing for the optimum set of criteria with respect to reliability, technological efficiency, construction time, and cost of adjusted expenditures;
| | – |
minimization of one-time and total excavation for the banquette, providing for the least disruption of the slope in the process of construction;
| | – |
draining of moraine loams, which has no known analog;
| | – |
the use of an ejector unwatering system, which provides for minimum adjusted expenditures on construction and operation of the drainage system.
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Deceased. 相似文献
5.
Model studies of the hydraulic operating conditions of an eddy tunnel outlet with an inclined shaft showed that:
| – |
for regimes without delivery of air into the flow core with swirler parameterA=1.1 and with delivery of air for all values ofA, submergence of the outlet section of the conduit in the lower pool noticeably affects the size of the core and promotes
the formation of a hydraulic jump zone along the tunnel;
|
| – |
insignificant (in value) submergences of the exit section of the tunnel have little effect on the discharge capacity of the
outlet (their differences is Δ=1.4% forA=0.6, Δ=2.71% forA=1.1, and submergence even increases the discharge of the outlet Δ=0.8% forA=0.83).
|
| – |
delivery of air into the flow core has little effect on the discharge capacity of the structure, with the exception of the
layout with a swirler withA=0.6 (Δ=4.31% forA=0.6, Δ=0.5%, and Δ=0.9% forA=1.1);
|
| – |
considerable vacuums are observed for regimes without air in the flow core, the absolute values of which with increase ofA drop intensely from Hfc=−4.5 m to Hfc=−0.3m;
|
| – |
delivery of air into the flow core markedly reduces the vacuums in it and their values are close to zero;
|
| – |
with increase of swirler parameterA the area occupied by the flow at the end of the tunnel decreases;
|
| – |
regimes without delivery of air into the flow core are the most favorable with respect to the conditions of the pressure distribution
on the conduit walls;
|
| – |
submergence on the downstream side does not lead to an increase of pressure on the conduit walls if the vacuum in the flow
core increases simultaneously with this.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 41–44, November, 1997. 相似文献
6.
| 1. |
A comparison of laboratory and on-site data on a determination of the maximum range of oscillations at the end of a direct hydraulic jump when waves enter it from a chute with the results of calculations by theoretical formulas (1), (2), and (3) confirms the applicability of one of these formulas (2) for superrapid flow and flow transitional from superrapid to rapid.
| | 2. |
The stilling basin generates secondary waves, reaching half of the depth of the basin d with respect to its height. With submergence of the basin from the lower pool, the range of variations of the level increases additionally by 2.0–2.5 times.
| | 3. |
On the apron behind the stilling basin, the drop of waves is insignificant, since the wave transformation coefficient at distance (40–90)hn, where hn is the natural depth, remains equal to
.
| | 4. |
The periods and lengths of the waves transformed in the stilling basin decrease with increase of discharge and Froude number Fr0 and approach in value the wave periods.
| | 5. |
Formulas (6) and (10) were obtained for calculating the maximum amplitude of oscillations of the free surface and maximum depth at the crest of oblique waves on the narrowing sections of the wave chutes and they were checked experimentally, which proved the applicability of these formulas for calculating a nonstationary oblique hydraulic jump.
| | 6. |
The proposed empirical formulas (12)–(17) can be recommended for an approximate evaluation of the parameters of the largest first waves on the narrowing stretch.
| | 7. |
Under these conditions, the use of a stilling basin as an energy dissipator of a superrapid flow is not rational, since not dissipation but generation of secondary waves is observed in it.
When designing narrowing sections of chutes, it is necessary to take into account an increase of depth of the oblique jump with passage of roll waves. 相似文献
7.
| 1. |
The morphometric method of estimating the geometry of stable canal channels, as based on a deeper physical nature and using the fluvial process theory principle, has become most popular in solving the problem of designing canals in alluvial soil. It can be considered that sufficiently reliable relations have presently been obtained which can be used in practice with consideration of the particular canal operating conditions.
| | 2. |
More detailed investigations of the separate consideration of the transport of bottom and suspended sediments on stability for providing channel stability of canals when vvne are needed for refining the morphometric relations.
| | 3. |
It is necessary to continue investigations of the effect of the sediment concentration of a flow on the velocity structure of the flow and noneroding velocity.
| | 4. |
It is necessary to consider as one of the most important problems of open-channel hydraulics the activation of experimental and theoretical investigations of the three-dimensional turbulent structure of a flow for the purpose of estimating the distributon of local velocities in the flow cross section as a function of the size of the channel and roughness of its walls.
| | 5. |
For dynamically stable canal channels investigations are needed for estimating the roughness coefficient as a function of the channel size , shape, sediment concentration of the flow, and bed-load transport.
| | 6. |
It is necessary to prepare the relevant materials for compiling standard data on the design of dynamically stable canals.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 3, pp. 37–42, March, 1991. 相似文献
8.
| 1. |
Sludge storage ponds can be located on any foundation soils, but economic calculations should be made for selecting the site.
| | 2. |
In the presence of seismic conditions, it is necessary to remove weak soils within the shoulder in order to provide its stability with a steepness of the downstream slope up to m=5. Other methods providing stability of the shoulder can also be used with appropriate technical and economic substantiation.
| | 3. |
The stability and possible liquefaction of soils of the shoulder should be determined only according to the guide Consideration of seismic loads when designing hydraulic structures, which is the only standard with respect to this problem.
| | 4. |
The size of the hydraulic-fill beach is determined on the basis of the particle-size distribution of the slurry.
| | 5. |
The permissible minimum width of the hydraulic-fill beach is determined on the basis of calculating the stability of the shoulder.
| | 6. |
It is necessary to recommend the construction of a siphon intake (discharge) located on the bank of the settling pool, which gives a more reliable and economical solution.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 12, pp. 53–55, December, 1991. 相似文献
9.
Conclusions
| 1. |
When searching for the optimal steel percent needed for providing the bearing capacity of a specimen, it is necessary to take
into account the factor of reinforcement arrangement in the soil.
|
| 2. |
It is seen from the dependences γcd*=f(ζ) obtained for specimens with various steel percent that with an increase of the factor of reinforcement arrangement in
soil ζ the work conditions factor decreases, which makes it possible to introduce the given factor in formula (1) for determining
γcd*.
|
| 3. |
The lining of the model must be regarded as an element increasing the bearing capacity of the reinforced earth model.
|
| 4. |
In the case of a discontinuous and continuous lining the bearing capacity of the models (with the same steel percent) is higher
than that of models with a flexible lining.
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Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 3, pp. 19–21, March, 1998 相似文献
10.
Conclusions
| 1. |
The concrete of the Vilyui III hydrostation is characterized by a strength exceeding the grade and a high modulus of elasticity,
and for the structural members of the main structures by a long stay during construction at low temperatures —to minus 15–35°C.
|
| 2. |
The strength and deformation characteristics determined by tests of specimens and cores from mature concrete (up to 4.6 years)
of grades M250 W8 F100, M300 W10 F100, and M400 W12 F400 were: cube Rcub and prism Rpr strengths, respectively, 40–57 and 20–45 MPa; initial modulus of elasticity Ec=(4–4.3)·104 MPa and Poisson's ratiov=0.127; for M250 and M300 Rpr/Rcub=0.65 and for M400, 0.8.
|
| 3. |
The initial modulus of elasticity of the on-site concrete M250 at an age of 400–500 days at positive temperatures was Ec=4.6·104 MPa. Freezing of concrete to minus 30°C leads to an increase of Ec by 1.6 times according to a linear dependence. An increase of Ec practically ceases in the minus 30–38°C temperature range.
|
| 4. |
The strength and deformation characteristics of the concrete obtained as a result of tests, which considerably exceed the
standard values and those adopted in the design, can be used for analyzing the state of the main structures of the Vilyui
III hydrostation during the construction and operation periods and when processing the results of observations by means of
the installed monitoring and measuring instruments.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 7, pp. 11–14, July, 1998. 相似文献
11.
| 1. |
A pressure dangerous with respect to cavitation is observed in those places where the vortex core closely approaches the conduit wall (there are places where with formal conversion to the prototype vacuums m H2O are observed, actually the absolute values will be close to the vaporization pressure).
| | 2. |
Delivery of air to ducts for the given spillway design reduces but does not remove the dangerous vacuum on the conduit walls.
| | 3. |
Large vacuums are recorded both over the length of the outlet conduit and in the dissipation chamber.
| | 4. |
The most effective (of those investigated) means of eliminating the vacuum on the conduit wall and in the dissipation structure are the installation of longitudinal ribs and transverse diaphragms in the outlet tunnel and delivery of air to the end of the swirler and dissipation chamber.
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Deceased. 相似文献
12.
Conclusions
| 1. |
A mathematical model of the oxygen regime of a stratified reservoir, which makes it possible to calculate this regime for
a selective water intake with allowance for variation of the balance between the production, expiration, and destruction of
phytoplankton with varying depth of this intake, and also with consideration given to photosynthetic aeration of the epilimnion
and hypolimnion, is developed.
|
| 2. |
Results of this calculation indicate that the oxygen content near the bottom of the reservoir increases with increasing depth
of selective water intake, and reaches a maximum when water is drawn off only from the hypolimnion. On the whole, these results
suggest that selective water intake can be used as a rather effective nature-conserving measure to improve the oxygen regime
of a reservoir in its near-bottom layers and to prevent the development of starvation phenomena here.
|
| 3. |
With the reservoir in service, this goal can be achieved by drawing off water from the hypolimnion using a bottom water outlet,
which can be activated during the summer when the oxygen content near the bottom drops to a critical level (below 4 mg/liter),
or by increasing the drawdown of water during this period through the turbines of the hydroelectric plant (with water drawn
off from the zone of the thermocline). Under these conditions, however, the intake of water from the surface layer (epilimnion),
for example, by drawing it down through a spillway dam, as computational results have shown, may lead only to degradation
of the reservoir's oxygen regime.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 2, pp. 42–49, February, 1999. 相似文献
13.
Conclusions
| 1. |
A method was developed for calculating the average cross-sectional flow velocities over the length of a fishholding chute.
|
| 2. |
PC programs were developed which are recommended to be used when calculating and designing fishways with continuous delivery
of water along the length of the fish-holding chute.
|
| 3. |
Experimental data characterizing the projections of the total velocities of the added (detached) mass onto the direction of
the velocity of the main flow were obtained. Experiments established that for the given problem the values of the varying
mass coefficientsn do not change over the length of the fish-holding chute and do not depend on the character of the permeable barrier or investigated
relations of the hydraulic and geometric parameters. The values ofn for calculating the hydraulic regimes should be taken within 0.145 and 0.160.
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| 4. |
At the initial time of its movement toward the working chamber the stimulating device should be placed at a certain distance
from the entry. This distance is calculated by the programs developed for a PC. Movement of the stimulating device leads to
a change in the character of the addition and separation of discharges between the galleries and chute. This provides favorable
hydraulic regimes in the fish-holding chute for the fish species being passed.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 3, pp. 50–53, March, 1997. 相似文献
14.
| 1. |
More than a decade of operation of water-cleaning machines with a conical net has demonstrated their good technical and economic characteristics as regards failure-free operation and water-cleaning performance.
| | 2. |
After a simple modification, the existing water-cleaning machines with a vertical axis of cone rotation can perform a fish-protecting function.
| | 3. |
For larger water consumers (such as water supply systems of thermal and nuclear power plants) machines with a horizontal cone rotation axis are recommended (so-called directflow water-cleaning machines). With some modernization of the flowthrough component, water offtake facilities can ensure bypass and survival of over 90% of young fish without building any expensive fish guard structures.
| | 4. |
Instead of fish guard facilities planned to be built at operating thermal and nuclear power plants, one should consider the possibility of removing the existing water-cleaning machines with flat nets and installing machines with conical nets.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 12, pp. 37–40, December, 1990. 相似文献
15.
An analysis of the experience in the Soviet Union and in foreign countries with conveyor transportation in the mining industry,
as well as with use of conveyors in hydraulic construction shows that the introduction of conveyor transportation in the field
of construction of embankment dams in this country, for delivery of earth-rock material from quarries, as well as for carrying
raw materials to concentrating plants processing nonmetallic minerals, will make it possible.
| 1) |
To reduce substantially the personnel nees.
|
| 2) |
To lower significantly the transportation costs for delivery of earth-rock materials to construction sites and to concentrating
plants processing nonmetallic mateirals (rubble, gravel, and sand);
|
| 3) |
To reduce the need for trucks, by replacing them with conveyors;
|
| 4) |
To increase the rate of delivery of earth-rock materials from quarries for dam, construction and, consequently, to reduce
the times of completion.
|
| 5) |
To reduce the volume of housing, cultural-welfare, and auxiliary-subsidiary construction in owing to the lower needs for personnel
in conveyor transportation;
|
| 6) |
To eliminate the need for constructing a large number of roads with rigid pavements for large-capacity dump trucks;
|
| 7) |
To raise the technical level of the earth-rock work.
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相似文献
16.
| 1. |
Oscillations due to low-frequency sources of excitation beneath the impeller in the draft tube develop in long pipelines of water-storage power plants.
| | 2. |
For the Zagorsk water-storage power plant with a long (790 m) and flexible pipeline, the natural frequency of the first type of the system's oscillation is many times lower than the predominant frequency of the lowest-frequency component of the spectrum of pressure fluctuations beneath the impeller (0.24–0.25)fre. For a shorter and stiffer pipeline, the system would approach resonance.
| | 3. |
The dynamic properties of the system depend on the opening of the guide apparatus: for small openings, the natural frequency approaches f1=(C/4)L; with large openings, it approaches f2=(C/2)L.
| | 4. |
When the unit is operating in the stationary mode, the hydrodynamic loads on the pipe lining do not exceed 0.05 MPa; this corresponds to an additional stress of 0.07 MPa in the lining and vibrational displacements of 0.183 mm (when C=780 m/sec), i.e., not more than 0.06 of the radius of the pipeline; when C=965 m/sec, the vibrational displacements do not exceed 0.08 mm.
| | 5. |
The loads on the pipeline supports do not exceed 0.36 tons on any one pile.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 8, pp. 27–30, August, 1992. 相似文献
17.
| 1. |
The designs as well as the total safety factor of concrete-encased steel pressure conduits of operating hydraulic structures
were analyzed.
|
| 2. |
The principles of the existing standards related to calculations of concrete-encased steel pressure conduits were analyzed.
|
| 3. |
Methods of calculating concrete-encased steel pressure conduits (including forks and distributors), including elements of
the inside steel shell and reinforced-concrete part, were developed.
|
| 4. |
The calculation methods developed were experimental substantiated and tested during designing and constructing domestic and
foreign objects.
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Translated from Gidrotekhnicheskoe Stroitel'stvo No. 1, pp. 37–44, January, 1999 相似文献
18.
Conclusions
| 1. |
Considering the urgent need to ensure a reliable year-round supply of electric power and process and drinking water to Khabarovsk,
it is recommended to accelerate construction of the sediment/floating-anchor-ice/ice-protection shore bucket on the Amur River
near the pumping plant for the Khabarovsk-3 thermal power plant with hooded intake heads with an overall productivity of 17,000
m3/h and 100% reserve.
|
| 2. |
The study that we conducted is an example of the solution of complex problems, when specialists of various organizations are
drawn upon to work as members of temporary creative teams. This is a reflection of the trend toward market relations in conducting
scientific-research and experimental-construction work.
|
| 3. |
Many of the solutions developed were first used in a complex; they may also be useful for other power plants or intake structures.
|
| 4. |
The Khabarovskénergo and the profession as a whole should be interested in completing the construction of the designs that
have been developed, since this will solve many problems of the supply of process and drinking water and make it possible
to work out typical solutions for other projects with similar floating-anchor-ice/ice and channel complications.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 29–31, May, 1997. 相似文献
19.
| 1. |
The hydraulic characteristics of cohesive mudflows in the case of a hydraulic jump, other conditions being equal, differ considerably from those for a pure water flow.
| | 2. |
The scheme of calculating a hydraulic jump of a cohesive mudflow requires taking into account, along with the hydrostatic pressure, also the pressure caused by cohesive forces and angle of internal friction of the mudflow mixture.
| | 3. |
The change in the ratio of the depth H2/H1 before and after the jump completely depends on the kinetics parameter of the mudflow, values of cohesion and angle of internal friction.
| | 4. |
Several subcritical depths, determined by the concentration of the mudflow mixture and physical and mechanical properties of the medium, correspond to the jump function of a cohesive mudflow.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 12, pp. 45–47, December, 1991. 相似文献
20.
| 1. |
In certain cases of constructing dams salt-containing soils serve as their foundation.
| | 2. |
Under these conditions reliable operation of the structures can be provided only by developing special engineering measures to control dissolution.
| | 3. |
All existing methods of protecting saliferous foundation soils of hydraulic structures from dissolution can be divided into passive, active, and combined.
| | 4. |
The combined methods should be considered the most effective for preventing removal of salts from foundation soils by the seepage flow.
| | 5. |
Large-scale field investigations of the work of the combined method of protecting saliferous foundation soils of the planned Lower Kafirnigan hydro development showed its high effectiveness even in the case of complex engineering-geological conditions at the construction site.
| | 6. |
Individual elements of the set of dissolution protective measures investigated under field conditions can be used in hydrotechnical and hydropower construction practice.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 10–14, October, 1994. 相似文献
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