簡介
鳳灘水電站位(wei)于(yu)中國湖南省沅陵縣、沅水支流酉水下游,距(ju)沅陵縣45km。混(hun)凝土空腹(fu)重力拱壩(ba),最大壩(ba)高112.5m,校核洪水位(wei)時總庫容(rong)17.33億m3,1970年(nian)(nian)(nian)10月開工(gong),1978年(nian)(nian)(nian)5月第一臺(tai)機(ji)(ji)組發(fa)(fa)電,1979年(nian)(nian)(nian)完工(gong)。老(lao)廠裝機(ji)(ji)容(rong)量40萬(wan)kW,保證(zheng)出力10.3萬(wan)kW,多年(nian)(nian)(nian)平均發(fa)(fa)電量20.43億kW·h,2004年(nian)(nian)(nian)左岸擴機(ji)(ji)兩臺(tai)20萬(wan)kW機(ji)(ji)組投運,隨后進(jin)行(xing)老(lao)廠2號機(ji)(ji)組增容(rong)工(gong)程,總裝機(ji)(ji)容(rong)量達到81.5萬(wan)kW。以(yi)發(fa)(fa)電為主,兼顧(gu)防洪、航運、灌溉、養殖等。
結構
壩址為(wei)(wei)"U"形河(he)谷,枯水(shui)期河(he)床寬140m,河(he)床右側礁石灘寬100m,地層(ceng)為(wei)(wei)前震旦系板溪砂巖夾少量板巖,巖性(xing)致密堅硬,但(dan)斷層(ceng)、節理(li)發育。地震烈(lie)度為(wei)(wei)5度。 壩址以上(shang)流(liu)(liu)域(yu)面(mian)積17500平方(fang)(fang)公里,多年(nian)平均(jun)流(liu)(liu)量504立(li)方(fang)(fang)米(mi)/秒,實測最大(da)流(liu)(liu)量16900立(li)方(fang)(fang)米(mi)/秒,多年(nian)平均(jun)輸(shu)沙(sha)量352萬立(li)方(fang)(fang)米(mi)。千年(nian)一遇設(she)計洪(hong)(hong)水(shui)流(liu)(liu)量29400立(li)方(fang)(fang)米(mi)/秒,相應(ying)洪(hong)(hong)水(shui)位209.56m,5000年(nian)一遇校核洪(hong)(hong)水(shui)流(liu)(liu)量34800立(li)方(fang)(fang)米(mi)/秒,相應(ying)洪(hong)(hong)水(shui)位221.4m,相應(ying)庫容(rong)(rong)17.33億(yi)立(li)方(fang)(fang)米(mi)。正(zheng)常蓄水(shui)位205m,相應(ying)庫容(rong)(rong)13.9億(yi)立(li)方(fang)(fang)米(mi),死水(shui)位170m,相應(ying)庫容(rong)(rong)3.3億(yi)立(li)方(fang)(fang)米(mi),調節庫容(rong)(rong)10.6億(yi)立(li)方(fang)(fang)米(mi)。汛(xun)期防(fang)洪(hong)(hong)控制水(shui)位198.5m,防(fang)洪(hong)(hong)庫容(rong)(rong)6.22億(yi)立(li)方(fang)(fang)米(mi)。水(shui)庫淹沒耕地495公頃。遷移人(ren)(ren)口(kou)1.1萬人(ren)(ren)。
樞紐布置
樞紐(niu)建(jian)筑物包括混凝土空(kong)腹拱壩(ba)、放(fang)空(kong)兼(jian)泄洪底孔,壩(ba)內廠房和過(guo)(guo)船過(guo)(guo)木筏道。
空腹重力拱壩
壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)頂高(gao)程(cheng)221.5m,壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)頂弧長488m,為(wei)(wei)定圓心(xin)定半徑拱(gong)(gong)(gong)。大(da)(da)(da)壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)共分27個壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)段(duan)(duan)(duan)(duan),拱(gong)(gong)(gong)冠左側為(wei)(wei)廠(chang)(chang)房壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)段(duan)(duan)(duan)(duan),位(wei)于(yu)(yu)枯水河(he)(he)槽,最(zui)(zui)(zui)大(da)(da)(da)壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)高(gao)112.5m,最(zui)(zui)(zui)大(da)(da)(da)底寬60.44m;拱(gong)(gong)(gong)冠右側為(wei)(wei)溢流壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)段(duan)(duan)(duan)(duan),位(wei)于(yu)(yu)河(he)(he)床礁(jiao)石(shi)灘上(shang),最(zui)(zui)(zui)大(da)(da)(da)壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)高(gao)106.5m,最(zui)(zui)(zui)大(da)(da)(da)底寬59.5m;兩岸為(wei)(wei)非溢流壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)段(duan)(duan)(duan)(duan)。壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)內空(kong)(kong)(kong)腹(fu)沿壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)軸(zhou)(zhou)線(xian)長255.8m。廠(chang)(chang)房壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)段(duan)(duan)(duan)(duan)空(kong)(kong)(kong)腹(fu)高(gao)40.1m,寬20.5m。溢流壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)段(duan)(duan)(duan)(duan)空(kong)(kong)(kong)腹(fu)寬28m,壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)前腿(tui)(tui)寬20m,壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)后腿(tui)(tui)寬11.5m。空(kong)(kong)(kong)腹(fu)斷面為(wei)(wei)橢圓曲(qu)線(xian),橢圓長軸(zhou)(zhou)基本(ben)上(shang)與荷載的(de)合力(li)平行,向上(shang)游傾(qing)斜(xie)。為(wei)(wei)便于(yu)(yu)施(shi)工,空(kong)(kong)(kong)腹(fu)拱(gong)(gong)(gong)頂由一個兩心(xin)圓曲(qu)線(xian)組成(cheng),空(kong)(kong)(kong)腹(fu)高(gao)度控制在約1/3壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)高(gao),頂點(dian)(dian)高(gao)程(cheng)139.1m。采(cai)用(yong)空(kong)(kong)(kong)腹(fu)重力(li)拱(gong)(gong)(gong)壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)除了能協調泄(xie)洪與廠(chang)(chang)房布(bu)置的(de)矛盾,節(jie)省工程(cheng)量外(wai),其本(ben)身特點(dian)(dian)是改善了壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)體(ti)應力(li),使超(chao)載能力(li)增大(da)(da)(da),有(you)利于(yu)(yu)壩(ba)(ba)(ba)(ba)(ba)(ba)(ba)基排水和混(hun)凝土散(san)熱降溫。
放空兼泄洪底孔
溢洪道布置(zhi)在8~12號(hao)壩(ba)(ba)(ba)段(廠(chang)房壩(ba)(ba)(ba)段)和(he)12~20號(hao)壩(ba)(ba)(ba)段(溢流(liu)壩(ba)(ba)(ba)段)上。溢洪道凈寬(kuan)(kuan)182m,堰頂高(gao)程(cheng)193m,共有(you)13孔(kong)(kong),裝有(you)寬(kuan)(kuan)14m、高(gao)13.13m的弧(hu)形(xing)鋼閘門,最(zui)大(da)單寬(kuan)(kuan)流(liu)量(liang)170立方(fang)米/秒。為了(le)(le)減少水(shui)(shui)流(liu)及(ji)回流(liu)淘刷壩(ba)(ba)(ba)腳,壩(ba)(ba)(ba)下(xia)采(cai)用了(le)(le)兩岸(an)混凝土護(hu)坡和(he)河床護(hu)坦(tan)等措施。為了(le)(le)防止下(xia)泄(xie)量(liang)大(da)時(shi)(shi)出(chu)現水(shui)(shui)流(liu)集中,下(xia)游沖刷加劇現象,并考慮下(xia)游水(shui)(shui)墊淺、地(di)質(zhi)條件不利、抗沖能力低(di)(di)的情況,采(cai)用高(gao)低(di)(di)坎(kan)空中碰擊消能方(fang)式,6孔(kong)(kong)高(gao)坎(kan),7孔(kong)(kong)低(di)(di)坎(kan),相間布置(zhi),挑坎(kan)高(gao)差達(da)28m。低(di)(di)挑坎(kan)為連續式,高(gao)挑坎(kan)為舌(she)式擴(kuo)(kuo)散型。泄(xie)洪時(shi)(shi)形(xing)成上下(xia)兩層水(shui)(shui)流(liu),在橫向和(he)縱向(空中)碰撞,強烈擾動,擴(kuo)(kuo)散摻氣,消能效果(guo)良好。 在右岸(an)21號(hao)壩(ba)(ba)(ba)段設有(you)一個放空兼泄(xie)水(shui)(shui)底孔(kong)(kong),矩(ju)形(xing)進(jin)(jin)水(shui)(shui)口(kou),斷面(mian)尺寸為6m×12m,進(jin)(jin)口(kou)底坎(kan)高(gao)程(cheng)145m,進(jin)(jin)口(kou)設平板事(shi)故檢修門,出(chu)口(kou)設弧(hu)形(xing)工作(zuo)門,斷面(mian)尺寸6m×7m。死水(shui)(shui)位時(shi)(shi)泄(xie)量(liang)為812立方(fang)米/秒;校核洪水(shui)(shui)時(shi)(shi),可輔(fu)助溢洪道宣泄(xie)流(liu)量(liang)1280立方(fang)米/秒。
壩內廠房
壩(ba)(ba)(ba)內式(shi)廠(chang)房布置(zhi)在(zai)9~12號(hao)壩(ba)(ba)(ba)段空腹內,廠(chang)房長85m,寬20.5m,高40.1m,裝有4臺(tai)10萬kW混流式(shi)發電機(ji)(ji)組。水(shui)輪機(ji)(ji)為HL702-LJ-410型,轉輪直(zhi)徑(jing)4.1m。引水(shui)系(xi)統(tong)采用(yong)深井(jing)式(shi)引水(shui)道,單機(ji)(ji)單管引水(shui),進(jin)水(shui)口布置(zhi)在(zai)9~12號(hao)壩(ba)(ba)(ba)段的溢流壩(ba)(ba)(ba)閘墩首部,4根直(zhi)徑(jing)5.6m的壓力鋼(gang)管沿(yan)上游面(mian)垂直(zhi)下降,然后水(shui)平穿過壩(ba)(ba)(ba)體(ti)。主廠(chang)房右側布置(zhi)220kV開關(guan)站及2臺(tai)220kV自耦變壓器。第一副廠(chang)房和110kV變電開關(guan)站布置(zhi)在(zai)左岸非溢流壩(ba)(ba)(ba)后。
過船過木筏道
船、筏道布置(zhi)于右岸(an)非(fei)溢流(liu)壩段,沿右岸(an)山坡布置(zhi),采(cai)用雙重垂直橋(qiao)吊加斜面升船機的綜合方(fang)(fang)案。上游(you)(you)通(tong)航水(shui)位(wei)205~170m,下游(you)(you)通(tong)航水(shui)位(wei)114.2~117.36m。可通(tong)過50t級船只,年過壩能力為(wei)木材10萬(wan)t,貨物10萬(wan)t。2條(tiao)直徑(jing)1.6m的灌溉引(yin)水(shui)管布置(zhi)在(zai)右岸(an)21~22號壩段內(nei),引(yin)用流(liu)量為(wei)8立方(fang)(fang)米/秒。
工程施工
工程總量為(wei)土石方開(kai)挖61萬立(li)方米,混(hun)凝土澆(jiao)(jiao)筑(zhu)122.8萬立(li)方米,鋼筋(jin)及鋼材(cai)用(yong)量2.03萬t。 采用(yong)二期(qi)(qi)施(shi)(shi)工,第一(yi)期(qi)(qi)由(you)明渠導流,第二期(qi)(qi)由(you)壩體導流底孔過(guo)流。在空腹封拱和(he)廠房(fang)拱頂施(shi)(shi)工時采用(yong)預(yu)制拱肋(lei)和(he)拱架,其跨度達15.35m,重量分別3.85t和(he)9t,按(an)雙鉸拱設(she)計,用(yong)10t門機(ji)吊(diao)裝就位于大壩伸出(chu)的牛腿(tui)上(shang),上(shang)鋪預(yu)制板后進行拱頂混(hun)凝土澆(jiao)(jiao)筑(zhu)。 施(shi)(shi)工過(guo)程中發(fa)生過(guo)圍(wei)堰被沖毀和(he)副廠房(fang)進水、發(fa)電機(ji)被淹等事故。1980年8月4日大壩下泄12500立(li)方米/秒時,沖壞了下游(you)兩岸公路。