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.
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 5, pp. 23–25, May, 1989. 相似文献
The side curtains as necessary cutoff elements of the al-Qadisiyah hydro development were made in an optimal design variant, on time, and with a high quality. A considerable technical and economic effect was obtained by eliminating excessive volumes of works specified by the original design as a result of a combined analysis of the data of engineering surveys, investigations of experimental grouting works, and optimization of the grouting technology.
2.
The index of unit cement absorption in the control holes used as the criterion of sufficiency of grouting on the side curtains should be used everywhere where the purpose of grouting works is to detect and eliminate large cavities and fissures.
3.
Grouting works on elimination of karst cavities and large fissures, being in essence infill grouting, require the development of an industrial technology of the works with the use of considerable volumes of grouts (concretes) and use of a large number of machines and mechanisms (concrete plants, mixers, concrete pumps, etc.).
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 1, pp. 45–50, January, 1989. 相似文献
Borehole bench marks I–VI practically work just as the settlement marks of the dam and surface cliff bench marks located near the dam.
Consequently, with such a scheme of embedding the bench marks it was not possible to fall outside the zone of formation of settlement, and the given borehole bench marks cannot serve as a reliable, independent reference for determining dam settlements. 相似文献
During operation of large multipurpose reservoirs their unsatisfactory sanitary and engineering state, ineffective use of their water and biological resources, and unfavorable ecological conditions were revealed, which requires their immediate improvement.
2.
There are real ways of improving these sanitary state and use of the water and biological resources of reservoirs, which were established when drawing up the schemes.
3.
A thorough elaboration of ecological problems of the examined reservoirs aimed at an improvement of the ecological conditions on each reservoir and on the territories adjacent to them is required.
4.
To solve the stated problem it is necessary to implement a number of coordinated measures. For this purpose, a scientifically founded approach based on a prediction of the results of their accomplishment is required. The interrelatedness and interdetermination of these measures with respect to increasing the effectiveness of using water, land, and biological resources should be based on scientific approaches of aquatorial regionalization and planning of reservoirs. Such an approach, unfortunately, is absent in many schemes.
5.
The investments and expenditures being provided for the indicated purposes should be aimed at achieving priority goals on improving the sanitary state of reservoirs, water quality, and effective use of their resources. The investments provided for in the schemes should be based on real sources of financing and should be coordinated with the plan of the concerned organizations, which are the title holders of the objects planned for construction.
For a porosity of about 5% the quality indices of APC are at the level of the requirements of the existing specifications P20-85:KF0.85,R20>3 MPa,R50>1.2 MPa,Kth>2.5–3.
2.
The experiments on the impermeability of APC showed that material with a porosity of 4–5% withstands a water pressure of 0.2–0.3 MPa without its infiltration through the specimens.
3.
The results obtained give grounds to revise the traditional requirements imposed on the residual porosity — not more than 3% — of APC-base structural members. Compaction of asphaltic and asphaltic polymer-impregnated concrete mixes to a residual porosity of 4–5% will make it possible to reduce expenditures on compaction. In this case, variants of compacting mixes to various residual porosities are possible in combination with surface treatment of the material with sealing compositions (for example, with a bitumen-polymer binder) which must be substantiated by technical and economic calculations for the particular conditions of conducting works on constructing watertight facings of hydraulic structures.
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 28–30, November, 1988. 相似文献
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:
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
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.
Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 11, pp. 21–23, November, 1992. 相似文献
Conclusion The proposed method of detecting local defects in a cutoff curtain has a large radius of investigation and allows testing a 30-m-long section of the curtain during one experiment.Each experiment takes about 4 h. The area of use is limited to an evaluation of the quality of grout curtains constructed below the groundwater level. The method is intended for use together with other existing methods for increasing the details of checking grout curtains.In addition to a qualitative solution of the quality control problem (detection of local defects in the grout curtain), the method makes it possible to obtain a quantitative evaluation of the achieved effect based on solving the problem of the relation between the measured parameter
and effect of grouting
obtained for a homogeneous (porous) medium.The use of the described geophysical method of checking the quality of grout curtains makes it possible to increase the reliability of their work and to promptly introduce necessary changes into the grouting technology.Translated from Gidrotekhnickeskoe Stroitel'stvo, No. 7, pp. 23–27, July, 1986. 相似文献
Zusammenfassung Es wird eine optimale Strategie im Sinne des minimalen erwarteten Verlustes für die beiden Entscheidungeny>yo undyyo aufgrund der Messungen einer mitY positiv korrelierten, einfacher und/oder billiger zugänglichen ZufallsvariablenX abgeleitet. Dabei wird angenommen, daßX undY nach einer bivariaten Normalverteilung mit bekannten Parametern verteilt sind und die Entscheidungyyo getroffen wird, wennx größer ist als ein zu bestimmendesxo, und die Entscheidungy>yo, wennx gleich oder kleiner als diesesxo ist. Für die Bestimmung des optimalenxo werden zunächst die Kosten für die beiden Fehlentscheidungen jeweils als konstant vorausgesetzt, in einem weiteren Ansatz wird jedoch für die Mißklassifikationyyo eine mity exponentiell wachsende Risikofunktion angenommen. Um die relative Häufigkeit der zu erwartenden Fehlklassifikationen abschätzen zu können, wird schließlich die bedingte WahrscheinlichkeitP(x>xo,y) errechnet.
Summary An optimal strategy, with minimum expected risk, for the decisionsy>yo oryyo is constructed on the basis of the measurement of a variableX, which is positively correlated withY and can be measured more easily and/or with smaller expense. A bivariate normal distribution with known parameters is assumed forX andY. For the observationsx a limitxo is aimed at, so that the decisionsy>yo oryyo are taken ifx>x orxxo respectively. Optimal values ofxo are first calculated under the assumption of constant losses for the two misclassifications (x>xo ifyyo andxxo ify>yo). In a further approach the loss for a wrong decisionyyo is assumed to increase exponentially withy. Finally the conditional probabilityP (x>xo\y) is calculated to get an assessment of the relative frequencies of wrong decisions to be expected.
