水庫土壩的泄槽水力計(jì)算和出口消能設(shè)計(jì)計(jì)算案例目錄TOC\o"1-3"\h\u176381.1泄槽水力計(jì)算 1241901.2出口消能設(shè)計(jì) 71.1泄槽水力計(jì)算1.泄槽的布置根據(jù)設(shè)計(jì)資料給定的條件，此次工程將泄槽的位置布置在泄槽上，分別為收縮段、泄槽一段、泄槽二段。由水庫資料可知，工程收縮角為10°，首端底寬和控制段均為B=4m，末端底寬b擬定為2.5m,斷面取為矩形，則漸變段長L1=（B-b）/tanθ=（4-2.5）/tan10°=4.25m，取整，L1=5m，底坡i=1/25泄槽一段上接收縮段，下接泄槽二段，擬斷面為矩形，寬b=2.5m，長L2=41.3m，底坡i=1：6。泄槽二段斷面為寬2.5m的矩形，長L3為53m，底坡i=1：4。2.泄槽水面曲線計(jì)算1)基本公式式中：C為謝才系數(shù)；R：為水力半徑；A：為過水?dāng)嗝婷娣e；：為濕周；I：為泄槽底坡。2)漸變段水面曲線計(jì)算(1)臨界水深hk及臨界底坡i。漸變斷首端寬B=4m,尾端b=2.5,斷面為矩形。具體見計(jì)算表8-5表8-5溢洪道漸變段臨界水深和臨界底坡計(jì)算計(jì)算情況QBkqkhkAkkRCik設(shè)計(jì)水位4.741.210.482.125.140.45357.760.00425校核水位6.441.580.892.785.670.5359.140.00416漸變段i=1/10>ik,，故屬于陡坡急流。(2)漸變段水面曲線計(jì)算。首端斷面水深試算得:設(shè)計(jì)洪水位時(shí),h0=0.19m;校核洪水位時(shí)h0=0.25m。具體計(jì)算見表8-6。8-6溢洪道漸變段水面曲線計(jì)算計(jì)算情況Qh1q1A11R1V1E1i1設(shè)h2q2A2設(shè)計(jì)水位4.70.21.230.824.380.246.452.260.10.10.31.79校核水位6.40.231.651.004.610.366.782.450.120.432670.96計(jì)算情況2R2v2E2i2R`vLnhfE1+iLE2+hf設(shè)計(jì)水位3.10.256.352.410.10.256.315.000.0230.362.682.71校核水位3.280.316.762.630.10.286.545.000.0350.312.892.93由計(jì)算得漸變段末端水深分別為h設(shè)=0.3m,h校=0.39m。3)泄槽一段水面線計(jì)算泄槽一段斷面為矩形，寬2.5m,長41.3m，i=1/5。(1)臨界水深hk及臨界底坡ik,具體計(jì)算見表8-7。表8-7泄槽一段臨界水深和臨界底坡計(jì)算計(jì)算情況QBkqkhkAkkRCik設(shè)計(jì)水位4.72.51.930.781.823.940.4858.480.004631校核水位6.42.52.620.92.234.310.5959.70.00481i=1/5>ik，故泄槽一段屬于急流，按陡槽計(jì)算。表8-8溢洪道泄槽一段正常水深計(jì)算計(jì)算情況Qbi設(shè)h0A00R0C0K0Q0設(shè)計(jì)水位4.72.50.260.20.613.10.249.910.44.72校核水位6.42.50.240.290.722.990.2851.5814.486.83經(jīng)試算，設(shè)計(jì)水位時(shí)，h0=0.20m;校核水位時(shí)，h0=0.29m。(3)泄槽一段水面線采用分段求和法，按水深將進(jìn)行分段，具體計(jì)算見表8-8.4)泄槽二段水面線計(jì)算泄槽二段斷面為矩形，寬2.5m,長53m,底坡為i=1/1.5.求臨界水深hk、控制斷面水深h。因泄槽二段同泄槽一段大致相同，故臨界底坡和臨界水深不變。i=1/1.5>ik,屬于陡坡急流?？刂茢嗝嫠頷0用試算法，具體計(jì)算列于表5-11。.表8-9溢洪道泄槽二段正常水深計(jì)算計(jì)算情況Qbi設(shè)h0A00R0C0K0Q0設(shè)計(jì)水位4.72.51/1.50.130.352.780.1347.155.794.73校核水位6.42.51/1.50.180.422.840.1548.497.846.40經(jīng)試算，設(shè)計(jì)水位時(shí)，h0=0.13m;校核水位時(shí)，h0=0.18m。泄槽二段水面線。泄槽二段首端控制深，設(shè)計(jì)水位時(shí)h=0.20m;校核水位時(shí)h=0.25m。采用分段求和法計(jì)算水面線，具體計(jì)算見表5-12。由計(jì)算知，末端水深在設(shè)計(jì)水位時(shí)為h=0.13m,校核水位時(shí)，h=0.18m。5)溢洪道邊墻高度的確定(1)溢洪道邊墻高度計(jì)算公式。其計(jì)算公式為:H=h+hb+Δ(5-7)式中h:不摻氣時(shí)水深，m;hb:當(dāng)流速大于7~8m/s時(shí)摻氣增加水深，m;Δ:安全超高，設(shè)計(jì)時(shí)取1.0，校核時(shí)取0.7m;H:邊墻高度，m。hb的計(jì)算公式為:hb=ζhv/100式中v:不摻氣情況下計(jì)算斷面的平均流速，m/s;ζ:修正系數(shù)，一般為1.0~1.4s/m，當(dāng)流速大時(shí)宜取大值。(2)引水渠導(dǎo)水墻高度計(jì)算。引水渠導(dǎo)水墻高度見表8-10。表8-10引水渠邊墻高度計(jì)算設(shè)計(jì)情況h（m）(m)H=h+設(shè)計(jì)水位1.041.002.04校核水位1.260.501.96(3)陡坡邊墻高度計(jì)算?？刂蒲叩倪厜Ω叨扰c引水渠同高:設(shè)計(jì)水位時(shí):邊墻高H=2.04m;校核水位時(shí):邊墻高度H=1.96m，最終控制堰邊墻高度為2.04m。收縮段邊墻高度具體計(jì)算見表8-11。收縮段最大流速v=6.56m//s<7~8m/s,不考慮摻氣所增加水深，故H=h+△。泄槽一段邊墻高度具體計(jì)算見表8-12.泄槽二段邊墻高度具體計(jì)算見表8-13表8-11溢洪道收縮段邊墻高度計(jì)算情況斷面斷面距漸變段首端距離（m）計(jì)算水深（m）安全超高▽（m）邊墻高度H（m）設(shè)計(jì)水位首端00.191.01.19末端50.31.01.3校核水位首端00.250.70.95末端50.390.71.09表8-12溢洪道泄槽一段邊墻高度計(jì)算情況斷面斷面距離槽首端距離（m）計(jì)算水深h(m)流速v(m/s)hs=vh/100(m)△(m)H(m)設(shè)計(jì)水位1-100.36.27均小于7m/s11.32-22.100.296.7111.293-36.890.267.520.00211.284-49.780.257.830.00211.275-518.530.248.550.00211.266-641.410.2049.220.00211.22校核水位1-100.376.56小于7m/s0.71.072-23.420.347.310.0030.71.043-36.120.327.760.0030.71.024-411.910.318.530.0030.71.015-523.820.269.480.0030.71.966-640.890.2410.240.0030.70.94表8-13溢洪道泄槽二段邊墻高度計(jì)算情況斷面斷面距離槽首端距離（m）計(jì)算水深h(m)流速v(m/s)hs=vh/100(m)△(m)H(m)設(shè)計(jì)水位1-100.219.40.0211.232-21.060.209.890.0211.223-32.460.1910.440.0211.194-44.360.1811.060.0211.205-511.850.1712.530.0211.196-625.230.1513.430.0211.17校核水位1-100.2510.240.030.700.982-20.970.2310.670.030.700.963-32.100.2211.130.030.700.954-45.430.2012.190.030.700.935-511.420.1813.470.030.700.916-630.470.1615.060.030.700.891.2出口消能設(shè)計(jì)溢洪道出口的地勢平坦，而且河流地帶較為開闊，設(shè)計(jì)采用底流消能，可以減緩水流沖擊作用對大壩帶來的不安全威脅。下面以設(shè)計(jì)水位為例說明消力坎的水力計(jì)算，相關(guān)參數(shù)為流量Q=4.7m3/s，寬度b=2.5m，單寬流量q=1.88m2/(m·s)。1.判斷是否需要建消力坎:以泄槽二段末端的水深當(dāng)作臨界水深hc,經(jīng)泄槽二段的水面線計(jì)算知設(shè)計(jì)水位時(shí)末端水深為0.15m,所以hc=0.15m.hc的共軛水深為:因此，需建消力坎。2.坎高c的計(jì)算:設(shè)過坎水流為自由溢流，取σ=1.05，m=0.42，由下計(jì)算坎高c:檢驗(yàn)所設(shè)溢流狀態(tài),故與假設(shè)相同。為自由溢流第一級(jí)消力池長計(jì)算因?yàn)?<Fr<16,故自由水躍躍長計(jì)算公式為:池長的計(jì)算公式為:4.判斷是否需建第二級(jí)消力坎現(xiàn)由下式試算出hc。將c=1.337，q=1.88，m=0.42，φ=0.90代入上式，整理得:，通過列表試算得hc=0.33m。hc的共軛水深為:所以第一級(jí)消力坎后發(fā)生遠(yuǎn)離水躍，需要建第二級(jí)消力坎。5.第二級(jí)消力坎高c的計(jì)算:設(shè)過坎水流為自由溢流，取σ=1.05，m=0.42，由下式計(jì)算坎高c:檢驗(yàn)所設(shè)溢流狀態(tài),為淹沒溢流，故與假設(shè)溢流狀態(tài)相反，應(yīng)按淹沒溢流計(jì)算。設(shè)c=0.4m，由下式計(jì)算H10由,由"s_I0=0.556，查表8-14得σS=0.984，并取m=0.42，則表8-14σs值hs/H10≤0.450.500.550.60.650.70σs1.000.9900.9850.9750.9600.940與所設(shè)c=0.4m不等，應(yīng)再設(shè)c值計(jì)算。與所設(shè)c=0.4m不等，應(yīng)再設(shè)c值計(jì)算。H10=1.01m得c=0.468m，與所設(shè)0.47很接近，故可選定