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doi: 10.1007/BF02443113pmid: N/A
1. The drag coefficients were determined experimentally for a rapid flow past a continuous wall of rectangular cross section with a height in the range C/h1=1/3–5/3 for Foude numbers from 20 to 110. 2. It was shown that the reaction related from the effect of the forward flow on the upstream face of the wall is negligibly small if the wall is located lower than the front part of the roller of the jump at a distance of more than 3.5–4 jump heights; the given wall can be regarded as a spillway. 3. The possibility of extrapolating dependence (7) for determining the optimal wall height for which a minimum lower pool depth is needed for submergence of the jump, from Fr=100 to Fr=200, was confirmed. 4. After substantiation, the use of baffles or basin with a length of not more than 1.5 jump heights can be recommended.
doi: 10.1007/BF02443115pmid: N/A
1. The main problems when designing pressure tunnels are the maximum use of the bearing properties of the enclosing soil mass and prevention of leakage of water from the structure into the mass. The first condition is fulfilled completely in the case of using unlined tunnels, but here the second problem is not always solved. The optimal solution satisfying both requirements in high-head tunnels is the use of a combined lining consisting of an inner steel lining and outer concrete ring. 2. The length (boundary) of the steel lining in a pressure tunnel is determined on the basis of two criteria: the bearing capacity of the rock mass; the size and length of the seepage path from the tunnel into “dry” underground workings or to an open slope. 3. The criteria of the bearing capacity of the rock mass is characterized by two main parameters: deformation-strength characteristics and height of the stratum covering the tunnel. 4. The criterion of the size and length of the seepage path is determined by the seepage strength of the rock mass and stability of the underground workings an open, slopes located in the zone of the seepage flow issuing from the tunnel. 5. At present there is no unified method of determining the boundaries of a steel lining in pressure tunnels. This problem is solved in each particular case with consideration of the engineering-geologic, topographic, technological, operating, and economic conditions.
doi: 10.1007/BF02443116pmid: N/A
1. The head, power, efficiency, and vacuum-gauge suction head during operation of floating suction dredges change depending on the depth of submergence of the suction pipe underwater and do not depend of soil size. 2. The output of dredges varies with underwater depth of the suction pipe. The greater the depth of submergence of the suction pipe, the more the output of the dredge decreases. 3. The performance curves of the soil pumps recorded during operation on water and soil-water mixture under test-bed (laboratory) and field conditions on soils of various sizes and density correspond to those calculated by formulas (8–11).
doi: 10.1007/BF02443117pmid: N/A
1. An original complete method of hydraulic calculation of rapids with intensified roughness was developed on the basis of the author's multiple-aspect experimental studies and his earlier developed [7, 8, 9, 10, 17] system of universal dependences and hypotheses concerning hydraulic resistances (15), stabilized aeration (9), velocity of the liquid phase (10), and critical aeration states (7). 2. An important component of the new method is the formula of the resistance coefficient (24), the structure of which follows from (15), and the relative reduced height of the ribs is used as the argument. Thanks to such a combination, the values of the constants of formula (24) for ribs placed only on the bottom and of ribs placed on the entire perimeter were unified and the “effect of width” known in hydraulics was overcome. The values of the constants of formula (24) for the six investigated types of ribs are given in Table 3. 3. The new method has also a way to calculate chutes with zigzag ribs with an unlimited (n>2) number of zigzags on the basis of a standard calculation for n′=2, using relations (33). Relation (40) for assigning the minimum (for a given b) number of zigzags not leading to disturbance of the normal distribution of velocities and depths at the entry to the discharge canal was also substantiated preliminarily. 4. The problems solved in the work, in which the initial data of laboratory (unaerated flows) and on-site (aerated flows) investigations were used for comparing the results of calculations by the new method with the actual values of the quantities being sought show that calculation by the new method of the indicated quasi-uniform flows and parameters of the ribs on chutes with intensified roughness reduces to simple operation taking several lines on the basis of the Chezy (or Darcy) formula, dependences (7), (9), (10), (12), and formula (24). The results of these calculations in all cases are exceptionally close to the actual values of the quantities being sought, which indicates the engineering reliability of the new method. 5. The significance of the correspondence of the calculation results to the actual data noted in the preceding paragraph goes beyond the bounds of the new method, since it, by a completely specific example, confirms the universality of the dependences (7), (9), (10), (15), developed earlier and approved prior to this on objects of other categories, used in the calculations. 6. The new method, taking into account the universality of the formulas underlying it, the wide limits of its experimental base and approval, is recommended for using in the entire engineering range. Restrictions are related only to formula (24), since the values of its experimental constants, given in Table 3, are real when conditions (1) and (2) are fulfilled. We recommend also in practical calculations staying in the intervals of values of Δ/h0 indicated in Table 3 and which per se are sufficiently wide.
Kasatkin, Yu.; Lyadov, Yu.; Nogionov, Yu.; Romanov, Yu.
doi: 10.1007/BF02443119pmid: N/A
1. Experience has been gained at the construction site in constructing the membrane, including at negative outside air temperatures, which with sufficient financing will make it possible to place 15,000–20,000 m3/yr of asphaltic concrete even with the existing technology. 2. The composition of poured asphaltic concrete BKG-2 provides stability of its characteristics during hauling and placing in the membrane. 3. The existing technological regulations for conducting works preclude the possibility of the formation of discontinuities of the membrane both in the summer and winter construction periods.
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