第頁(yè)灌區(qū)渠道的橫斷面設(shè)計(jì)計(jì)算案例目錄TOC\o"1-3"\h\u6990灌區(qū)渠道的橫斷面設(shè)計(jì)計(jì)算案例 151971.1相關(guān)參數(shù)確定 158661.2渠道水力計(jì)算 2211781.3支其他渠道計(jì)算計(jì)算 3284211.4最小水深計(jì)算 413481.5過(guò)水?dāng)嗝嬉陨喜糠殖叽绲挠?jì)算 4設(shè)計(jì)渠道時(shí)根本要求就是工程量小，投資少，平均流速滿足不沖、不淤要求。渠道一般是正坡，水力學(xué)設(shè)計(jì)按照明渠均勻流進(jìn)行。1.1相關(guān)參數(shù)確定首先確定輸水流量、比降、糙率、邊坡系數(shù)、寬深比包括渠道不沖、不淤流速等。1.1.1設(shè)計(jì)渠底比降i為按照本次畢業(yè)設(shè)計(jì)要求。隨著設(shè)計(jì)流量的逐級(jí)減小，渠底比降逐級(jí)增大。本設(shè)計(jì)中選取的各級(jí)渠道渠底比降，如下表所示。表4.6渠道渠底比降表渠道干渠支渠斗渠農(nóng)渠比降11111.1.2渠床糙率系數(shù)n渠床早率系數(shù)是反映渠床粗糙程度的技術(shù)參數(shù)，根據(jù)本次畢業(yè)設(shè)計(jì)要求，干渠可用0.0225，支渠可用0.025。1.1.3渠道邊坡系數(shù)m邊坡系數(shù)大小關(guān)系到渠坡的穩(wěn)定，要根據(jù)渠床土壤質(zhì)地和渠道深度等條件選擇適宜的數(shù)值。土壤質(zhì)地為中壤土，根據(jù)設(shè)計(jì)流量，大致確定水深在1～2m，挖方邊坡系數(shù)m取1.25，填方的內(nèi)外邊坡系數(shù)取為1.0。1.1.4渠道斷面寬深比α寬深比α是渠道底寬b和水深h的比值。其設(shè)計(jì)比降小的渠道應(yīng)選較小的寬深比，以增大水力半徑，加快水流速度；比降大的渠道應(yīng)選較大的寬深比，以減小流速，防止渠床沖刷。表4.7流量與寬深比關(guān)系表設(shè)計(jì)流量(m3/s)<11～33～55～1010～3030～60b/h1～21～32～43～55～76～101.1.5渠道不沖、不淤流速渠道的不沖流速：水在流動(dòng)時(shí)，土地顆粒將要移動(dòng)而尚未移動(dòng)時(shí)的水流速度就是不沖流速。渠道的不淤流速：水流的挾沙能力隨流速的減小而減小，當(dāng)流速小到一定程度時(shí)，泥沙就開(kāi)始在渠道內(nèi)淤積。根據(jù)畢業(yè)設(shè)計(jì)要求和相關(guān)規(guī)范，不沖流速V不沖=0.65-0.85m/s根據(jù)畢業(yè)設(shè)計(jì)要求渠道流速不小于0.3-0.4m/s1.2渠道水力計(jì)算根據(jù)具體要求，按照水力學(xué)中明渠均勻流公式進(jìn)行計(jì)算，計(jì)算公式有：A=b+m??（χ=b+2?1+m2R=Aχ（C=1nR1Q=ACRi（1.v=QA（式中：A——橫斷面的過(guò)水面積，mb——橫斷面底寬，m；m——邊坡系數(shù)；?——水深，m；——橫斷面濕周，m；R——橫斷面水力半徑，m；n——渠床糙率；Q——流量，m3/s；C——曼寧系數(shù)；i——比降；v——橫斷面平均流速，m/s。表4.8設(shè)計(jì)流量下橫斷面設(shè)計(jì)名稱干渠各段設(shè)計(jì)流量b/hB（m）h（m）A（㎡）濕周（m）RCQ計(jì)算校核v南干渠OA2.051.7821.154.2845.9570.73438.6172.1730.0510.520AB1.741.9321.053.7845.6300.68338.1891.8360.0510.500BC1.252.3320.852.8664.9780.59237.2201.2550.0100.449CD0.771.991.50.752.0404.1410.50036.2610.8060.0410.398DE0.3221.7810.551.0712.9780.36734.4050.3470.0510.326中支干渠A1B13.492.4231.256.1307.3030.85739.6273.4480.0310.571B1C13.252.5131.25.8147.1400.82639.4333.2130.0200.561C1D12.692.112.51.25.1826.6300.79639.1582.7740.0200.551D1E11.852.612.50.953.8255.8140.67338.0461.8260.0000.490E1F10.752.111.50.71.8673.9780.47935.9550.7140.0310.388北支干渠A1B23.422.4231.256.1307.3030.85739.6273.4480.0000.571B2C23.332.4231.256.1307.3030.85739.6273.4480.0410.571C2D23.152.5931.165.5697.0070.80639.2703.0190.0410.551D2E22.792.262.61.165.0806.5990.78539.0562.6930.0510.541E2F22.272.382.51.054.3456.1400.72438.5152.1830.0100.510F2G21.452.2220.93.0915.1410.61237.4751.3870.0410.459G2H20.661.981.40.71.7853.8760.46935.8630.6730.0200.388西干渠O1A16.924.461.3511.06710.6901.06141.0357.1600.0200.663設(shè)計(jì)流量與實(shí)際流量校核均最大值在于0.051，其他的設(shè)計(jì)流速流速均在不沖流速和不淤流速之間，滿足設(shè)計(jì)要求，其寬深比設(shè)計(jì)值也符合規(guī)范要求。1.3支其他渠道計(jì)算計(jì)算計(jì)算方法同上述干渠水力計(jì)算，具體設(shè)計(jì)列表如下表4.9支渠斗渠設(shè)計(jì)流量下橫斷面設(shè)計(jì)渠道流量b/hB（m）h（m）A（㎡）濕周RCQ計(jì)算校核v南干三支0.4661.46010.751.4393.4650.43136.2570.5040.0110.368南干三支斗0.1481.9530.80.450.6092.2890.27333.6420.1580.0110.273南干三支農(nóng)0.0251.3130.30.260.1471.1240.13730.0720.0210.0210.179中干八支0.5031.39710.781.5233.5700.45236.4560.5460.0110.378中干八支斗0.1051.9850.70.450.4521.9740.24232.8340.1050.0000.252中干八支農(nóng)0.011.1030.210.240.0950.8930.11628.9910.0110.0490.1471.4最小水深計(jì)算渠道底寬已確定，用最小流量推求干、支渠的最小水深，檢驗(yàn)各參數(shù)是否滿足要求。1.5過(guò)水?dāng)嗝嬉陨喜糠殖叽绲挠?jì)算1.5.1渠道的加大水深推求加大水深，本設(shè)計(jì)底寬已經(jīng)確定，故改變渠道的高程使其滿足流量和流速的規(guī)范要求即可。1.5.2安全超高和堤頂寬度為防止風(fēng)浪引起的溢流，保證渠道的正常運(yùn)行，開(kāi)挖渠道的岸坡和填筑渠道的堤頂應(yīng)高于渠道的增加水位，較高的數(shù)值可按以下公式怎么算。，為便于管理，確保航道安全運(yùn)行，填方航道堤頂和挖方航道岸坡應(yīng)達(dá)到一定寬度，以滿足交通和航道穩(wěn)定的需要。可按下列公式算。其中堤頂高度和寬度的計(jì)算公式如下：D=?j+0.3Δ?=14?j?頂=?j式中：Δ?——安全超高，m；?jD——渠岸或堤頂寬度，m；?頂表4.11渠道最大水深設(shè)計(jì)干渠各段QMAXb/hB（m）hj（m）A（㎡）濕周（m）RCQ計(jì)算校核v南干OA2.6651.7821.3915.1296.5100.81439.5932.7710.0210.556AB2.2621.9321.2364.3266.0150.74238.9962.1940.0410.525BC1.6252.3321.0823.5845.5210.67038.3371.7000.0100.484CD1.0011.9911.0302.3184.3260.55637.1320.9680.0520.433DE0.41861.7810.6901.2673.2340.40235.2360.4330.0000.350中支A1B14.5372.4231.5457.5298.0340.96840.7574.5630.0210.628B1C14.2252.5131.5357.4688.0030.95840.7264.5010.0420.618C1D13.4972.112.51.4426.1297.1890.87640.1193.4810.0310.587D1E12.4052.612.51.2154.8316.4680.77339.2532.5130.0410.536E1F10.9752.111.50.8762.2454.3470.53636.9050.9170.0420.422北支A1B24.4462.4231.5457.5298.0340.96840.7574.5630.0100.628B2C24.3292.4231.5457.5298.0340.96840.7574.5630.0520.628C2D24.0952.5931.4426.8507.7040.91740.3974.0070.0310.597D2E23.6272.262.61.4426.2737.2920.88640.1803.5840.0310.587E2F22.9512.382.51.3395.5216.8600.83439.7373.0280.0410.567F2G21.8852.2221.1333.8215.6860.69038.5631.8540.0210.505G2H20.8581.981.40.8762.1534.2440.52536.8020.8650.0000.412西干O1A18.9964.461.64813.18411.4541.18542.1799.1570.0000.711南干三支0.60591.46010.8451.7103.7290.47436.1740.6390.0100.391斗渠0.19241.9530.80.5150.7312.4720.30933.6500.2060.0210.288農(nóng)渠0.03251.3130.30.2880.1851.2360.15530.1070.0310.0310.185中干八支0.65391.39710.8761.8033.8320.48436.3490.6900.0210.391斗渠0.13651.9850.70.4330.5252.1010.25832.7330.1340.0210.258農(nóng)渠0.0131.1030.210.2370.1130.9790.12428.9740.0210.0210.155表4.12推求安全超高、堤頂寬度表干渠各段hj（m）Δh(m)h頂（m）D（m）南OA1.390.551.941.69AB1.240.511.751.54BC1.080.471.551.38CD1.030.461.491.33DE0.690.371.060.99中A1B11.550.592.131.85B1C11.530.582.121.83C1D11.440.562.001.74D1E11.220.501.721.5