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4.3-masala. Trapetsiya shaklli betondan yasalgan kanal uchun A. SHezi koeffitsientini aniqlang. Kanal o’lchamlari quyidagicha: tubining kengligi Ь = 5,0 m; undagi suvning chuqurligi h = 2,0 m; kanal yonbosh devorining nishabi t = 1,0 (4.28-rasm).
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4.28- rasm.


Echish. Bu xarakat ikkinchi darajali qarshilik oblastiga tegishli deb faraz qilamiz:

so = (b + mh)h = (5 +1,0 2) 2 = 14,0 m¹;

X = b + 2hJ\ + m² = 5 + 2 - 2 • -y/l,0 +1,0² =10,66 m;

Berilgan betonli kanal uchun p = 0,012; ^ = 83,3 ѐki k_sh=4,75.

A. SHezi koeffitsientini bir necha formulalar yordamida

xisoblaymiz.Gangile-Kyi ger formulasi (1869 y.)bu erda

R > 1,0, demak


87
5. X. Bazen formulasi (1897 y.)G = 87 - Rf , f , w o,5/r

12. 
    , 0,012^5D' ^{0 M} /S.
    

7PT I. I, Agroskin formulasi (1949 y.)

• 
  = 17,72(_sh + lgfl) = 17,72(4,75 + 0,117) = 86,2 m ^(,-⁵/s.
  

R ₊ 0,025 S = 25 A. D. Altshul formulasi (1954 y.)

87,7 m°'⁵/s.

(80/1 )⁶ V&7 8. A. YU. Umarov formulasi (1967 y.)

C = [4,921g(|)+2,94]Vs= 85,75 _mo,5_/s

bu erda beton uchun d=0,10 • 10"⁴m.

4.4-masala. 4.29-rasmdagi N quvurda xarakatlanayotgan suvning sarfi Q ni va undagi oqim tezligini aniqlang. Berilgan: N = 0,48 m; D = 0,15 m va / =50m.


Echish.Quvur N dagi suv xarakati paytida yo’qotilgan napor

• 
  = L „ + A . ,+ h
  

s.tur 1—2 chikish 1. Turdagi maxalliy qarshilik ta’sirida yo’qotilgan

1. 
   Manning formulasi (1890 y.)
   
2. 
   N. N. Pavlovskiy formulasi (1930 y.)
   

napor