簡介
鳳灘水(shui)(shui)電站位(wei)于(yu)中國湖南省沅陵縣、沅水(shui)(shui)支流酉水(shui)(shui)下(xia)游,距沅陵縣45km。混凝土(tu)空腹重力拱壩,最大(da)壩高112.5m,校核洪水(shui)(shui)位(wei)時(shi)總庫(ku)容17.33億m3,1970年10月開工(gong)(gong),1978年5月第一臺機(ji)組(zu)發(fa)電,1979年完(wan)工(gong)(gong)。老(lao)廠(chang)裝(zhuang)機(ji)容量(liang)40萬(wan)kW,保(bao)證出力10.3萬(wan)kW,多年平(ping)均發(fa)電量(liang)20.43億kW·h,2004年左(zuo)岸擴(kuo)機(ji)兩臺20萬(wan)kW機(ji)組(zu)投運,隨后進(jin)行老(lao)廠(chang)2號機(ji)組(zu)增容工(gong)(gong)程,總裝(zhuang)機(ji)容量(liang)達到81.5萬(wan)kW。以發(fa)電為主,兼顧防洪、航運、灌溉、養殖等。
結構
壩(ba)址為"U"形河谷,枯(ku)水(shui)(shui)期河床寬140m,河床右側礁石灘寬100m,地(di)(di)層為前震旦系板(ban)溪砂(sha)巖(yan)夾少量(liang)(liang)板(ban)巖(yan),巖(yan)性致密堅(jian)硬,但斷(duan)層、節(jie)理發育。地(di)(di)震烈度為5度。 壩(ba)址以上流(liu)域面(mian)積17500平方(fang)(fang)公里,多年(nian)(nian)平均流(liu)量(liang)(liang)504立(li)(li)(li)方(fang)(fang)米(mi)(mi)/秒(miao),實測最大流(liu)量(liang)(liang)16900立(li)(li)(li)方(fang)(fang)米(mi)(mi)/秒(miao),多年(nian)(nian)平均輸(shu)沙量(liang)(liang)352萬立(li)(li)(li)方(fang)(fang)米(mi)(mi)。千(qian)年(nian)(nian)一(yi)遇設計洪水(shui)(shui)流(liu)量(liang)(liang)29400立(li)(li)(li)方(fang)(fang)米(mi)(mi)/秒(miao),相(xiang)(xiang)應(ying)(ying)洪水(shui)(shui)位209.56m,5000年(nian)(nian)一(yi)遇校核洪水(shui)(shui)流(liu)量(liang)(liang)34800立(li)(li)(li)方(fang)(fang)米(mi)(mi)/秒(miao),相(xiang)(xiang)應(ying)(ying)洪水(shui)(shui)位221.4m,相(xiang)(xiang)應(ying)(ying)庫容(rong)(rong)17.33億(yi)立(li)(li)(li)方(fang)(fang)米(mi)(mi)。正(zheng)常蓄(xu)水(shui)(shui)位205m,相(xiang)(xiang)應(ying)(ying)庫容(rong)(rong)13.9億(yi)立(li)(li)(li)方(fang)(fang)米(mi)(mi),死水(shui)(shui)位170m,相(xiang)(xiang)應(ying)(ying)庫容(rong)(rong)3.3億(yi)立(li)(li)(li)方(fang)(fang)米(mi)(mi),調節(jie)庫容(rong)(rong)10.6億(yi)立(li)(li)(li)方(fang)(fang)米(mi)(mi)。汛期防洪控制(zhi)水(shui)(shui)位198.5m,防洪庫容(rong)(rong)6.22億(yi)立(li)(li)(li)方(fang)(fang)米(mi)(mi)。水(shui)(shui)庫淹沒耕地(di)(di)495公頃。遷移人口1.1萬人。
樞紐布置
樞紐建筑物(wu)包括混凝土空腹(fu)拱(gong)壩、放空兼泄洪(hong)底孔,壩內廠房和過船(chuan)過木筏道。
空腹重力拱壩
壩(ba)(ba)(ba)(ba)(ba)頂(ding)高(gao)(gao)程221.5m,壩(ba)(ba)(ba)(ba)(ba)頂(ding)弧長(chang)488m,為定(ding)圓心定(ding)半徑拱(gong)(gong)。大(da)(da)壩(ba)(ba)(ba)(ba)(ba)共分27個壩(ba)(ba)(ba)(ba)(ba)段,拱(gong)(gong)冠左側為廠房(fang)壩(ba)(ba)(ba)(ba)(ba)段,位于枯水(shui)河槽,最(zui)大(da)(da)壩(ba)(ba)(ba)(ba)(ba)高(gao)(gao)112.5m,最(zui)大(da)(da)底(di)寬(kuan)60.44m;拱(gong)(gong)冠右側為溢(yi)(yi)流(liu)壩(ba)(ba)(ba)(ba)(ba)段,位于河床礁石灘上(shang)(shang),最(zui)大(da)(da)壩(ba)(ba)(ba)(ba)(ba)高(gao)(gao)106.5m,最(zui)大(da)(da)底(di)寬(kuan)59.5m;兩(liang)岸(an)為非溢(yi)(yi)流(liu)壩(ba)(ba)(ba)(ba)(ba)段。壩(ba)(ba)(ba)(ba)(ba)內空(kong)腹(fu)沿(yan)壩(ba)(ba)(ba)(ba)(ba)軸線長(chang)255.8m。廠房(fang)壩(ba)(ba)(ba)(ba)(ba)段空(kong)腹(fu)高(gao)(gao)40.1m,寬(kuan)20.5m。溢(yi)(yi)流(liu)壩(ba)(ba)(ba)(ba)(ba)段空(kong)腹(fu)寬(kuan)28m,壩(ba)(ba)(ba)(ba)(ba)前腿寬(kuan)20m,壩(ba)(ba)(ba)(ba)(ba)后腿寬(kuan)11.5m。空(kong)腹(fu)斷面(mian)為橢圓曲線,橢圓長(chang)軸基(ji)本上(shang)(shang)與荷(he)載的合力(li)平(ping)行,向上(shang)(shang)游傾(qing)斜(xie)。為便于施工,空(kong)腹(fu)拱(gong)(gong)頂(ding)由一(yi)個兩(liang)心圓曲線組成,空(kong)腹(fu)高(gao)(gao)度控制在約1/3壩(ba)(ba)(ba)(ba)(ba)高(gao)(gao),頂(ding)點高(gao)(gao)程139.1m。采用空(kong)腹(fu)重力(li)拱(gong)(gong)壩(ba)(ba)(ba)(ba)(ba)除(chu)了(le)能協調泄洪與廠房(fang)布(bu)置的矛盾,節省工程量外,其本身特點是改善了(le)壩(ba)(ba)(ba)(ba)(ba)體(ti)應力(li),使超載能力(li)增大(da)(da),有利于壩(ba)(ba)(ba)(ba)(ba)基(ji)排水(shui)和混凝土散熱降(jiang)溫(wen)。
放空兼泄洪底孔
溢洪(hong)(hong)(hong)道(dao)布(bu)置(zhi)在8~12號壩(ba)(ba)(ba)段(duan)(廠房壩(ba)(ba)(ba)段(duan))和(he)12~20號壩(ba)(ba)(ba)段(duan)(溢流(liu)(liu)壩(ba)(ba)(ba)段(duan))上。溢洪(hong)(hong)(hong)道(dao)凈寬182m,堰頂高(gao)(gao)程193m,共有(you)13孔(kong),裝有(you)寬14m、高(gao)(gao)13.13m的弧形(xing)鋼閘門(men),最大(da)單寬流(liu)(liu)量(liang)(liang)170立方(fang)米/秒。為了減少水(shui)(shui)流(liu)(liu)及(ji)回(hui)流(liu)(liu)淘刷(shua)壩(ba)(ba)(ba)腳,壩(ba)(ba)(ba)下采用了兩岸混凝土(tu)護坡和(he)河床護坦等(deng)措(cuo)施。為了防止下泄(xie)量(liang)(liang)大(da)時出(chu)現(xian)水(shui)(shui)流(liu)(liu)集中,下游沖刷(shua)加劇(ju)現(xian)象(xiang),并考慮下游水(shui)(shui)墊淺、地質條(tiao)件不利、抗沖能力(li)低(di)的情(qing)況,采用高(gao)(gao)低(di)坎(kan)(kan)空中碰擊消能方(fang)式(shi),6孔(kong)高(gao)(gao)坎(kan)(kan),7孔(kong)低(di)坎(kan)(kan),相間(jian)布(bu)置(zhi),挑坎(kan)(kan)高(gao)(gao)差達28m。低(di)挑坎(kan)(kan)為連(lian)續式(shi),高(gao)(gao)挑坎(kan)(kan)為舌式(shi)擴(kuo)散型。泄(xie)洪(hong)(hong)(hong)時形(xing)成上下兩層水(shui)(shui)流(liu)(liu),在橫向和(he)縱向(空中)碰撞,強烈擾(rao)動,擴(kuo)散摻氣(qi),消能效(xiao)果良好。 在右岸21號壩(ba)(ba)(ba)段(duan)設(she)有(you)一(yi)個放空兼泄(xie)水(shui)(shui)底(di)孔(kong),矩形(xing)進水(shui)(shui)口,斷面尺寸為6m×12m,進口底(di)坎(kan)(kan)高(gao)(gao)程145m,進口設(she)平板事故檢修(xiu)門(men),出(chu)口設(she)弧形(xing)工作門(men),斷面尺寸6m×7m。死水(shui)(shui)位時泄(xie)量(liang)(liang)為812立方(fang)米/秒;校核洪(hong)(hong)(hong)水(shui)(shui)時,可輔助溢洪(hong)(hong)(hong)道(dao)宣泄(xie)流(liu)(liu)量(liang)(liang)1280立方(fang)米/秒。
壩內廠房
壩內(nei)式(shi)(shi)廠房(fang)布(bu)置在(zai)9~12號壩段(duan)空腹內(nei),廠房(fang)長85m,寬20.5m,高40.1m,裝有(you)4臺(tai)10萬kW混流(liu)式(shi)(shi)發電(dian)(dian)機(ji)組。水(shui)輪機(ji)為HL702-LJ-410型(xing),轉(zhuan)輪直(zhi)徑4.1m。引水(shui)系統采(cai)用深井式(shi)(shi)引水(shui)道,單(dan)機(ji)單(dan)管(guan)引水(shui),進水(shui)口布(bu)置在(zai)9~12號壩段(duan)的(de)溢流(liu)壩閘墩首部,4根直(zhi)徑5.6m的(de)壓力(li)鋼管(guan)沿上游面(mian)垂(chui)直(zhi)下降,然后水(shui)平(ping)穿過壩體(ti)。主(zhu)廠房(fang)右側布(bu)置220kV開關站及2臺(tai)220kV自耦變(bian)壓器。第一副廠房(fang)和110kV變(bian)電(dian)(dian)開關站布(bu)置在(zai)左岸非溢流(liu)壩后。
過船過木筏道
船、筏道布置于右(you)岸(an)(an)非溢流壩(ba)(ba)段(duan),沿(yan)右(you)岸(an)(an)山坡布置,采用(yong)雙重垂直橋(qiao)吊加斜面升船機的綜(zong)合(he)方案。上(shang)游通(tong)航水(shui)(shui)位205~170m,下游通(tong)航水(shui)(shui)位114.2~117.36m。可通(tong)過50t級(ji)船只,年過壩(ba)(ba)能力(li)為(wei)木材10萬(wan)(wan)t,貨物10萬(wan)(wan)t。2條(tiao)直徑(jing)1.6m的灌溉(gai)引水(shui)(shui)管布置在右(you)岸(an)(an)21~22號壩(ba)(ba)段(duan)內,引用(yong)流量為(wei)8立方米/秒。
工程施工
工(gong)(gong)程總量為土石(shi)方(fang)開挖61萬立(li)方(fang)米(mi),混凝土澆筑122.8萬立(li)方(fang)米(mi),鋼筋(jin)及鋼材用量2.03萬t。 采(cai)用二(er)期(qi)施工(gong)(gong),第(di)(di)一期(qi)由(you)明渠導流,第(di)(di)二(er)期(qi)由(you)壩體導流底孔過(guo)(guo)流。在空(kong)腹封拱(gong)和廠房(fang)拱(gong)頂施工(gong)(gong)時采(cai)用預(yu)制(zhi)(zhi)拱(gong)肋和拱(gong)架(jia),其跨度達15.35m,重(zhong)量分(fen)別3.85t和9t,按雙鉸(jiao)拱(gong)設(she)計,用10t門機(ji)吊裝就位于大壩伸出的(de)牛(niu)腿上(shang),上(shang)鋪預(yu)制(zhi)(zhi)板后進行拱(gong)頂混凝土澆筑。 施工(gong)(gong)過(guo)(guo)程中(zhong)發生(sheng)過(guo)(guo)圍堰被沖毀和副廠房(fang)進水、發電機(ji)被淹等事故。1980年8月4日大壩下(xia)泄12500立(li)方(fang)米(mi)/秒時,沖壞(huai)了下(xia)游兩(liang)岸公路(lu)。