[123doc.vn] - tinh toan mang luoi thoat nuoc mua.pdf

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  • Thuyt minh n mng li thot nc SVTH: Phm Th Tuyt Nhung

    Chng 4

    TNH TON MNG LI THOT NC MA

    4.1 MC CH

    Xc nh lu lng nc ma xi xungXc nh lu lng nc ma trong tng t

    4.2 XC NH LU LNG MA TNH TON

    Lu lng ma tnh ton xc nh theo phng php cng ma gii hn

    ntt t

    AFFqQ ==

    Trong :Qtt : lu lng ma tnh ton ca on ng (l/s) : h s dng chy

    1,02,0 tqTBtb = (Ztb: h s thc nghim, c trng cho tnh cht mt ph).F: din tch on ng phc v (ha)q: cng ma tnh ton (l/ha/s)n: s m (ph thuc vo vng a l), n = 1

    Gi s ta c din tch cc loi mt ph: Mi nh: 40% - 0,95 Mt ph atphan: 50% - 0,95 Mt c: 10% - 0,1

    Tnh h s dng chy trung bnh:

    1,02,0 tqTBtb =Trong q : cng ma (l/ha.s)t : thi gian matb h s lp ph tnh theo gi tr trung bnh cho ton din tch thot nc ma

    87,0865,0100

    1,01095,05095,040=

    ++=TB

    Lu lng n v dng chy

    ncro

    TBo ttt

    Aq)( ++

    =

    Xc nh thi gian ma tnh tonormtt tttT ++=

    Trong :

    GVHD: TS. Trn Th M Diu 4-1

  • Thuyt minh n mng li thot nc SVTH: Phm Th Tuyt Nhung

    tm: thi gian tp trung nc ma trn b mt t im xa nht n rnh, ph thuc vo din tch, cng ma v b mt lp che ph. Trong khu ph khng c rnh thot nc ma tm = 10 pht.

    tr: thi gian nc chy trong rnh, a hnh khng c rnh nn tr = 1 pht.

    to: thi gian nc chy trong ng n din tch tnh ton

    o

    oo v

    lMt =

    Tnh ton c th cho tuyn ng 8 9 10 11 - 12

    on ng 8 - 9

    Vi dc dc ng nh vn tc d kin l: v = 1,5 m/s

    Thi gian nc chy trong cng l

    44,11605,1

    8582,1 =

    =ot (pht)

    Thi gian tnh ton:

    t = to + tr + tm = 11,44+ 1 + 10 = 22,44 (pht)

    Lu lng nc ma cui on

    36044,22

    9,56927,1687,0 1 ===n

    tt tAFQ (l/s)

    Vi Q = 360 (l/s) ; v = 1,29 (m/s) th theo bng tra thy lc ta c: d = 900 mm ; i = 3105,2 .

    Kim tra vn tc trong cng gia kt qu tnh ton vi gi thit khng vt qu 15% th kt qu tnh ton c chp nhn.

    V h/d = 1 nn chn phng php ni ng theo nh cng.

    Chn su chn cng ban u ti ging 8 l 2 m.

    Tn tht p lc trn on cng 8 9 bng 3105,2 858 = 2,145 (m)

    y cng u tin ti ging 8 bng hiu s gia ct mt t v su chn cng4 2 = 2 (m)

    y cng ti ging 9 = 2 2,145 = - 0,145 (m)

    on ng 9 10

    GVHD: TS. Trn Th M Diu 4-2

  • Thuyt minh n mng li thot nc SVTH: Phm Th Tuyt Nhung

    Vi dc dc ng nh vn tc d kin l: v = 1,6 m/sThi gian nc chy trong cng l

    96,5606,1

    4772,1 =

    =ot (pht)

    Thi gian tnh ton:

    t = to + tr + tm = 5,96 + 22,44 + 1 + 10 = 28,4 (pht)

    Lu lng nc ma cui on

    7204,289,56923,4187,0 1 ===

    ntt t

    AFQ (l/s)

    Vi Q = 720 (l/s) ; v = 1,38 (m/s) th theo bng tra thy lc ta c: d = 1000 mm ; i = 3102 .

    on ng 10 11

    Vi dc dc ng nh vn tc d kin l: v = 1,7 m/sThi gian nc chy trong cng l

    41,7607,1

    6302,1 =

    =ot (pht)

    Thi gian tnh ton:

    t = to + tr + tm = 7,41+ 11,44 + 5,96 + 1 + 10 = 35,81 (pht)

    Lu lng nc ma cui on

    94281,35

    9,56906,6887,0 1 ===n

    tt tAFQ (l/s)

    Vi Q = 942 (l/s) ; v = 1,49 (m/s) th theo bng tra thy lc ta c: d = 1100 mm ; i = 3102 .

    on ng 11 12

    Vi dc dc ng nh vn tc d kin l: v = 1,8 m/s

    Thi gian nc chy trong cng l

    12,7608,1

    6412,1 =

    =ot (pht)

    Thi gian tnh ton:

    t = to + tr + tm = 7,12+ 7,41 + 5,96 + 11,44 + 1 + 10 = 42,93 (pht)

    Lu lng nc ma cui on

    GVHD: TS. Trn Th M Diu 4-3

  • Thuyt minh n mng li thot nc SVTH: Phm Th Tuyt Nhung

    108093,42

    9,56958,9387,0 1 ===n

    tt tAFQ (l/s)

    Vi Q = 1080 (l/s) ; v = 1,54 (m/s) th theo bng tra thy lc ta c: d = 1200 mm ; i = 3102 .

    on ng 12 x:

    Vi dc dc ng nh vn tc d kin l: v = 1,8 m/sThi gian nc chy trong cng l

    39,4608,1

    3952,1 =

    =ot (pht)

    Thi gian tnh ton:

    t = to + tr + tm = 4,39 + 7,12 + 7,41 + 5,96 + 11,44 + 1 + 10 = 47,32 (pht)

    Lu lng nc ma cui on

    109432,47

    9,56943,10487,0 1 ===n

    tt tAFQ (l/s)

    Vi Q = 1094 (l/s); v = 1,56 (m/s) th theo bng tra thy lc ta c: d = 1250 mm; i = 3109,1 .Tnh ton thy lc on ng 8 9 10 11 12 cng x c trnh by trong Bng 4.1.

    Bng 4.1 Tnh ton thy lc nc ma tuyn ng 8 9 10 11 12

    on ng

    Chiu di

    Din tch dng chy, ha Tc d

    Tc tnh

    Thi gian

    Lu lng

    ng knh

    dcBn thn

    Chuyn qua

    Tnh ton

    8 9 858 9,22 7,05 16,27 1,5 1,29 30,50 946 900 0,00259 10 477 6,18 35,05 41,23 1,6 1,38 42,40 1660 1000 0,0020

    10 11 630 8,69 59,37 68,06 1,7 1,49 56,40 2264 1100 0,002011 12 641 7,56 88,27 95,83 1,8 1,54 69,22 2714 1200 0,002012- CX 395 0 104,43 104,43 1,8 1,56 77,12 2817 1250 0,0019

    Bng 4.1 Tnh ton thy lc nc ma tuyn ng 8 9 10 11 12 (tip theo)

    on ng

    Tn tht p

    lc, m

    Cao su chn cngMt t nh cng y cng u Cui Gia

    u Cui u Cui u Cui8 9 2,15 4,00 3,80 2,90 0,76 2,00 -0,15 2,00 3,95 2,97

    9 10 0,95 3,80 3,70 0,76 -0,20 -0,25 -1,20 4,05 4,90 4,4710 11 1,26 3,70 3,60 -0,20 -1,46 -1,30 -2,56 5,00 6,16 5,5811 12 1,28 3,60 3,50 -1,46 -2,74 -2,66 -3,94 6,26 7,44 6,8512 - CX 0,75 3,50 3,40 -2,74 -3,49 -3,99 -4,74 7,49 8,14 7,82

    GVHD: TS. Trn Th M Diu 4-4