共查询到20条相似文献，搜索用时 15 毫秒
1.
| 1. |
The movement of slurry during suction occurs through the center of the suction tip in the form of a vortex; moreover, the velocity of the vortex depends on the vacuum, and the cross-sectional area of the tip.
| | 2. |
Vigorous suction of soil (slurry) takes place when the suction tip comes in contact with the surface of the soil or with the tip embedded into the stratum of soil.
| | 3. |
With other suction conditions equal, the bulk consistency of the slurry remains the same for different tips to which the suction tip is embedded in the soil stratum.
| | 4. |
The minimum suction velocity depends on the fineness of the soil. The coarser the soil, the higher the suction velocity required. The minimum suction velocity of soil is defined by the relationship|
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2.
| 1. |
The accuracy of modeling the velocity field depends heavily on the orthogonality of the grid being generated. Deviation from orthogonality even by 10° increases the ductility of the scheme markedly.
| | 2. |
It is necessary to relate bottom erosion not only to the tangential stresses on the bottom, but also the distribution of the kinetic energy of turbulence along the bottom.
| | 3. |
In studying channel deformations, a diffusion model with a terminal velocity is most effective, among other things, because it does not include difficult-to-determine diffusion coefficients that enter into a semi-empirical model.
| | 4. |
It is better to establish the adhesion condition, and not the reflection condition on the bottom for descending particles — this perceptibly changes the velocity of the bottom forms and their transformation.
| | 5. |
A change of ±50% in the transfer frequencies ik that enter into the diffusion model has virtually no effect on the computed deformation of the bottom.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 42–45, November, 1990. 相似文献
3.
| 1. |
Despite their openness, transverse discontinuous structures have a jetty effect.
| | 2. |
Discontinuous structures formed by two rows of rectangular support masses connected by longitudinal beams have the strongest effect on the dynamics of a pebble beach.
| | 3. |
It can be recommended to use circular supports with a diameter of not more than 2 m arranged in one row at a distance of at least 6 m from one another for constructing hydraulic structures intersecting pebble beaches.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 23–25, May, 1989. 相似文献
4.
| 1. |
Devices for measuring all dredge operating parameters were developed and tested.
| | 2. |
The devices developed are distinguished by simplicity of design, accessibility for manufacture in workshops, their installation and adjustment can be performed by the dredge crew according to the available instruments.
| | 3. |
The technical manuals can be sent by the authors by agreement with customers. For concluding an agreement, contact the article's coauthor N. N. Kozhevikov at the address: 105568, Moscow, Chechulin Street, house 22, apartment 22, telephone 308-80-96.
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Methods MI 1948 -88can ordered from Hydrotech enterprise at the address: 103062, Moscow, Chaplygin Street, house 5. 相似文献
5.
Conclusions
| 1. |
It was proved that the coefficient in front of the existing formulas for determing the critical sediment concentration of
flows are not constant, and their values depend on the sediment concentration of the flow
in accordance with dependence (12).
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| 2. |
A new dependence (13) for calculating the critical sediment concentration of a flow was obtained on the basis of processing
numerous existing on-site investigations.
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| 3. |
The regime of motion of suspended fine sediments (d≤0.25 mm) in tranquil open-channel flows occurs according to dependence
(13).
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| 4. |
Formula (13) can be recommended for practical use when calculating the critical sediment concentration in canals, settling
basins, and other streams transporting fine natural suspended material.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 1, pp. 20–23, January, 1997. 相似文献
6.
| 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:
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| – |
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
7.
| 1. |
Despite the decisions made repeatedly at various conferences and seminars, there are still no scientific design guidelines. As a consequence of this, crucial decisions are made without sufficient substantiation and thorough evaluation of the decisions made.
| | 2. |
Research institutes should not be limited to collecting data on settlements and temperature and seepage regimes of dams, but on the basis of data already available should give clear-cut standards and regulations for the design of earth structures in the northern construction-climatic zone.
| | 3. |
The construction of transition zones between the rock fill of the downstream shoulder and foundation, drainage blanket, and relief drainage is mandatory in all cases when the foundation is composed of fractured rocks covered by a diverse stratum of loose soils of various origin.
| | 4. |
The core-filters-drainage system should be a zone of increased attention when performing works and assigning the characteristics of the soils being placed.
As far as possible, it is necessary to change to dam designs with narrow cores protected by transition zones and developed drainage. When constructing such dams in the winter, especially in the case of heavy snow falls, it is easier to check the quality of placing the material in the zone of increased attention — core-filter. 相似文献
8.
| 1. |
An analysis of the results of a unique on-site experiment at the Sayano-Shushenskoe dam on regrouting the sites of column and radial joints under practically equal conditions was carried out for the first time in our country. Information about analogous works could not be found in the foreign literature.
| | 2. |
The works performed indicate the effectiveness and high performance of the multiple grout outlets designed by Gidrospetsstroi.
| | 3. |
Having equal conditions of grouting sites of column and section joints under conditions of the upper pool head (H=60 m), we can say the following:
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at a head H=60 m, the predominant opening of column joints compared to the opening of section joints located at the same elevation is observed during regrouting; this may be evidence of the action of the arch effect in a gravity-arch dam already during its construction; 相似文献
9.
| 1. |
The obtainment, as a result of numerous calculations on a computer, of generalized relations of the main indices of the load dropping process in the field TW/Tu–TW/TS makes it possible at the initial design stages to rapidly analyze the decisions made about the parameters of pressure conduits and pump-turbines and regulating regimes.
| | 2. |
By virtue of the peculiarities of the universal characteristics of reversible diagonal-flow pump-turbines, the maximum value of the temporal nonuniformity of the operation of the unit during load dropping in real ranges of the constants of inertia of the conduits and unit does not exceed the allowable standard value max=nmax/n0=1.6.
| | 3. |
The search for efficient regulating regimes reducing water hammer facilitates the introduction of the new concepts initial and final water hammer and plotting the corresponding zones on generalizing graphs.
| | 4. |
Rotating the runner blades of the diagonal-flow pump-turbines along with closing the gate apparatus after dropping the load is favorable for reducing water hammer. In this respect they can be more preferable than reversible mixed-flow pump-turbines for the same values of the heads, TW/TS and TW/Tu.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 1, pp. 23–27, January, 1991. 相似文献
10.
| 1. |
An intake structure with a closed flow having a vertical axis of rotation contributes to the development of a favorable kinematic structure in the channel, which makes it possible to minimize scouring beyond the structure.
| | 2. |
Excedence of the near-bottom average and maximum velocities above the average velocities in the channel comes about atl3.3hc downstream from the axis of the intake.
| | 3. |
The magnitude of the ratio of the maximum 1st-percentile and average 50th-percentile flow velocities (v1%/v50%), which characterizes the velocity pulsation, attains values for the undisturbed flow in the near-bottom region at a distancel4.1hc.
| | 4. |
Complete equalization of the plan diagram of velocities is noted at a distance (4.9–7.8)hc from the axis of the intake structure.
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Translated from Gidrotechnicheskoe Stroitel'stvo, No. 4, pp. 17–19, April, 1991. 相似文献
11.
| 1. |
The stockholder firm Gidrospetsstroi first developed, made feasible, and completely mastered a new procedure for work involving the monolithizing of large-diameter steel-reinforced-concrete pipelines in the domestic practice of special operations. 978 butt joints between individual elements have been successfully grouted.
| | 2. |
A procedure for monolithizing joints between reinforced-concrete elements in pipelines, which has been implemented in the construction of the Zagorsk water storage power plant, can be classified as a new technically complex form of special hydrotechnical operations. In conducting the work, it is necessary to focus attention on strict observance of the work procedure and on the possibility of bulging of the metallic lining of the conduit in the case where injection requirements are not observed. The work requires attending personnel with high qualifications, and should be accompanied by careful certification inspection to guarantee reliable quality of the work.
| | 3. |
Operations involving the monolithizing of butt joints in the steel-reinforced-concrete pressure pipelines have important principal differences with respect to the classical grouting of joints in monolithizing concrete dams and with respect to work involving the grouting of massive reinforced-concrete blocks possessing elements of a work procedure involving filler grouting beyond the facing in individual cases.
| | 4. |
The firm Gidrospetsstroi, which has significant experience in the design, technology, production, and quality control of special operations, guarantees their successful execution. The firm offers highly qualified specialists, production equipment, the timely publication of design-estimate documentation, and the realization of careful control (in the form of certification inspection) over the quality of their work.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 8, pp. 11–15, August, 1992. 相似文献
12.
| 1. |
The unique arch dam of the Chirkey hydroelectric power plant is operating under difficult conditions of high natural and excited seismicity under a geodynamic load from the left bank, which is not well defined. Reliable design solutions and the safety factor of the concrete have permitted its reliable operation to date.
| | 2. |
The rock mass enclosing the dam exhibits appreciably lower reliability. The clay interlayers contained in the rock and the pattern of dislocation lower the shear strength under the influence of saturation, changes in the upper-pool level, and repeated earthquakes. The safety of the hydraulic facility is determined by the stability of the laft-bank/dam/right-bank system under left-bank creep caused by the gravitational imbalance of the site.
| | 3. |
To retain the proper level of reliability and safety of the Chirkey hydroelectric power plant, it is necessary to perform check geomechanical calculations and organize state-of-art monitoring of geodynamic processes and an earthquake-forecasting service.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 30–35, May, 1994. 相似文献
13.
| 1. |
A increase of the height of the dam by stages as well as in construction time has a considerable effect on the SSS of the cofferdam, especially from stage II to VI.
| | 2. |
Development of stages of construction of the dam and its construction time leads to the following changes in the SSS of the cofferdam:
The levels of normal stresses
x,
y increase on average by more than 2 times; 相似文献
14.
| 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
15.
| 1. |
The design scheme of the 500-kV OEE of the Sayano-Shushenskoe hydrostation has a number of substantial shortcomings reducing the reliability of power output. Reconstruction of the middle network of the existing 4/3 scheme to three networks with two switches per connection is the most optimal variant of reconstruction. Sectioning of the collecting bus systems is necessary for a further increase of the reliability of the scheme.
| | 2. |
In the case of repair works on equipment of small nonstandard switchgear, such as the 500-kV OEE of the Sayano-Shushenskoe hydrostation, it is necessary to use special equipment and mechanisms, the development of which must be recommended to domestic industry.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 4, pp. 37–39, April, 1994. 相似文献
16.
| 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
17.
| 1. |
The results of the first full-scale experiments with orthogonal wind turbine generator units showed their performance, the possibility of creating on their basis large units of a simple design intended mainly for use in power systems.
| | 2. |
The maximum wind power coefficient of the rotorC
n somewhat exceeds the calculated values, reaching values of 0.50–0.56 at blade speeds equal to about three wind speeds.
| | 3. |
The aerodynamic drag coefficients of structural elements of type VL-2 rotors with guys can reach a=0.06–0.07, which substantially exceeds the profile drag of the operating blades. Elimination of the guys and a relative increase of the area of the working blades in type VL-2N rotors makes it possible to reduce the indicated drag coefficient to a=0.031–0.033.
| | 4. |
At wind speeds exceeding 0.5–0.6 the blade speed and power output of the unit cease to depend on the wind speed. This property of orthogonal units protects the generator from overloads, simplifies regulation, and increases the reliability of the plants.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 49–53, November, 1988. 相似文献
18.
| 1. |
The method of calculating flow on an overflow dam based on numerical solution of boundary-layer equations is presently preferable in comparison with the published methods based on integral relations of the boundary layer.
| | 2. |
To determine the value of the velocity coefficient in any section on the spillway, it is recommended to use the graph obtained on the basis of the proposed method.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 9, pp. 29–30, September, 1990. 相似文献
19.
| 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
20.
| 1. |
An industrial procedure for electrofacing by a powder wire of special composition has been developed to produce a wear-resistant coating up to 5 mm thick on the components of suction dredges. An increase of 4–6 times is achieved in the time to failure of the faced components, while the cost of these operations does not exceed the price of the initial article.
| | 2. |
It is expedient to use the facing procedure to strengthen new components under plant conditions and to restore worn parts at the site where the suction dredges are operated. The Scientific-Production Spetsstal' can perform work on electrofacing with the required materials, equipment, and technical accompaniment, and organize the strengthening of components at the plant.
| | 3. |
The installation of a three-channel suction dredge with effective water protection of components from abrasive wear while eliminating overflow of slurry into the pump and increasing the efficiency of the unit on the whole is proposed. The proposal is recommended for development and implementation.
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Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 3, pp. 10–13, March, 1995. 相似文献
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