簡介
銀(yin)盤水(shui)(shui)(shui)電(dian)站(zhan)(zhan)正常蓄(xu)(xu)水(shui)(shui)(shui)位(wei)(wei)215m,死水(shui)(shui)(shui)位(wei)(wei)211.5m,保證出(chu)力161.7MW,裝(zhuang)機容(rong)量(liang)600MW,多(duo)年平(ping)均(jun)發(fa)電(dian)量(liang)27.08億kW/h,庫水(shui)(shui)(shui)位(wei)(wei)每天(tian)在正常蓄(xu)(xu)水(shui)(shui)(shui)位(wei)(wei)215m和死水(shui)(shui)(shui)位(wei)(wei)211.5m之間變化。銀(yin)盤水(shui)(shui)(shui)電(dian)站(zhan)(zhan)水(shui)(shui)(shui)輪(lun)機正常運行(xing)水(shui)(shui)(shui)頭(tou)范圍為13~35.12m,加權平(ping)均(jun)水(shui)(shui)(shui)頭(tou)為29.66m,額(e)定水(shui)(shui)(shui)頭(tou)26.5m。其運行(xing)水(shui)(shui)(shui)頭(tou)屬(shu)低水(shui)(shui)(shui)頭(tou)且水(shui)(shui)(shui)頭(tou)變幅較大(da),該水(shui)(shui)(shui)頭(tou)是軸(zhou)流(liu)轉槳式(shi)機型(xing)較理(li)想的運行(xing)范圍。軸(zhou)流(liu)轉槳式(shi)水(shui)(shui)(shui)輪(lun)機具有效率(lv)曲(qu)線平(ping)坦、單位(wei)(wei)轉速高、穩定運行(xing)區域(yu)較寬廣(guang)等優(you)點(dian),適(shi)用于低水(shui)(shui)(shui)頭(tou)段且水(shui)(shui)(shui)頭(tou)變幅大(da)的電(dian)站(zhan)(zhan)。經綜合分析比較,本電(dian)站(zhan)(zhan)選用軸(zhou)流(liu)轉槳式(shi)水(shui)(shui)(shui)輪(lun)發(fa)電(dian)機組方案。
烏江(jiang)銀盤(pan)水(shui)(shui)電(dian)(dian)(dian)(dian)站由重(zhong)(zhong)慶(qing)大唐國際武隆水(shui)(shui)電(dian)(dian)(dian)(dian)開發(fa)有(you)限公司負(fu)責(ze)建設和(he)運(yun)營管理,目前,前3臺(tai)機組(zu)(zu)已投產(chan)發(fa)電(dian)(dian)(dian)(dian),第4臺(tai)機組(zu)(zu)也將于2011年底前投產(chan)發(fa)電(dian)(dian)(dian)(dian)。4臺(tai)機組(zu)(zu)全(quan)部投產(chan)運(yun)行后,每年將有(you)30億千瓦時電(dian)(dian)(dian)(dian)量(liang)并入(ru)重(zhong)(zhong)慶(qing)電(dian)(dian)(dian)(dian)網,可(ke)緩解(jie)重(zhong)(zhong)慶(qing)市電(dian)(dian)(dian)(dian)力(li)緊張局面,并增加武隆、彭水(shui)(shui)兩縣的財政收入(ru),帶動(dong)地區經濟發(fa)展。
工程技術
按照工(gong)程(cheng)(cheng)(cheng)總體施(shi)工(gong)計劃安排,導流明渠(qu)混(hun)(hun)凝土縱向(xiang)圍(wei)堰(yan)在2007年8月(yue)底(di)完(wan)工(gong),該(gai)圍(wei)堰(yan)需從高(gao)程(cheng)(cheng)(cheng)172m澆至堰(yan)頂217m,共上升45m,其(qi)中高(gao)程(cheng)(cheng)(cheng)184m以下為(wei)常態(tai)混(hun)(hun)凝土,高(gao)程(cheng)(cheng)(cheng)184m以上為(wei)碾壓混(hun)(hun)凝土,本工(gong)程(cheng)(cheng)(cheng)各類混(hun)(hun)凝土38.08萬立方米,混(hun)(hun)凝土月(yue)高(gao)峰(feng)期(qi)(qi)強度9.2萬立方米/月(yue),混(hun)(hun)凝土小時高(gao)峰(feng)期(qi)(qi)強度280立方米/h,由于(yu)各種客觀原(yuan)因,工(gong)期(qi)(qi)滯后,為(wei)了確保該(gai)工(gong)程(cheng)(cheng)(cheng)按期(qi)(qi)完(wan)成(cheng),黃(huang)河勘(kan)測規劃設(she)計有(you)限公(gong)司項目(mu)監理部(bu)、重慶國(guo)際水(shui)電開發公(gong)司項目(mu)工(gong)程(cheng)(cheng)(cheng)部(bu)、以及中國(guo)水(shui)電十四局項目(mu)部(bu)針對(dui)碾壓混(hun)(hun)凝土縱向(xiang)圍(wei)堰(yan)快(kuai)速(su)施(shi)工(gong)方案作了深入(ru)細致的(de)研究,并組(zu)織技術人員到外地考察(cha)學習,提出了采用(yong)大倉面斜層鋪筑(zhu)法并取得了良好(hao)的(de)效果。
該技術將(jiang)碾壓層(ceng)(ceng)(ceng)由平(ping)層(ceng)(ceng)(ceng)改為1∶10~1∶20的(de)(de)斜(xie)(xie)層(ceng)(ceng)(ceng),斜(xie)(xie)層(ceng)(ceng)(ceng)鋪(pu)筑法(fa)的(de)(de)具體做法(fa)是:開倉(cang)段(duan)(duan)先平(ping)層(ceng)(ceng)(ceng)鋪(pu)筑,且鋪(pu)筑層(ceng)(ceng)(ceng)自(zi)下(xia)而上依次遞加(jia),使新澆筑的(de)(de)混(hun)凝土表面形成一個(ge)斜(xie)(xie)面,至收倉(cang)端大部分(fen)混(hun)凝土按此斜(xie)(xie)面鋪(pu)筑,收倉(cang)段(duan)(duan)通過幾個(ge)依次加(jia)長的(de)(de)平(ping)層(ceng)(ceng)(ceng)收倉(cang),即平(ping)層(ceng)(ceng)(ceng)段(duan)(duan)、斜(xie)(xie)層(ceng)(ceng)(ceng)段(duan)(duan)、平(ping)層(ceng)(ceng)(ceng)段(duan)(duan)三部分(fen)組成(見圖1)。
避(bi)免(mian)在(zai)坡(po)腳(jiao)(jiao)部(bu)(bu)位(wei)形成薄層(ceng)尖腳(jiao)(jiao)和嚴格處理二(er)次(ci)污染是(shi)保證斜層(ceng)鋪筑(zhu)法施工質量(liang)的兩個(ge)主要問題,因薄層(ceng)尖腳(jiao)(jiao)部(bu)(bu)位(wei)骨料易被壓碎,在(zai)坡(po)腳(jiao)(jiao)部(bu)(bu)位(wei)應由人工清理骨料,清除坡(po)腳(jiao)(jiao)處厚度(du)小于(yu)10~20cm尖腳(jiao)(jiao)部(bu)(bu)位(wei)。其(qi)施工工藝流程(cheng)同平層(ceng)鋪筑(zhu)法一致,在(zai)此不(bu)再贅述。
特殊氣象條件下施工
高溫條件下的碾壓混凝土施工
高溫(wen)天氣施工,保證(zheng)(zheng)施工質量最(zui)根本的途徑(jing)是大幅(fu)度削減層間(jian)間(jian)隔時(shi)間(jian),同(tong)時(shi)采用控制和(he)補償表(biao)面(mian)水分蒸發(fa)散失的措施。斜層鋪筑(zhu)法,人為縮小澆筑(zhu)面(mian)積,大幅(fu)度削減層間(jian)間(jian)隔時(shi)間(jian),對混凝土(tu)的層面(mian)結合(he)質量和(he)抗剪能力都有可靠保證(zheng)(zheng)。
(1)施工倉面覆蓋(gai)
高溫條(tiao)件下,采用保溫被對(dui)(dui)(dui)倉面及時(shi)進行覆(fu)蓋,不僅可(ke)以起(qi)到(dao)保溫保濕的(de)作用,還可(ke)以延緩碾壓(ya)混(hun)凝土(tu)的(de)初(chu)凝時(shi)間(jian),減小VC值的(de)增加,同(tong)時(shi)對(dui)(dui)(dui)運輸車輛設(she)置遮陽遮雨棚,以降(jiang)低暴雨對(dui)(dui)(dui)混(hun)凝土(tu)拌(ban)和(he)物含(han)水量的(de)影響。
(2)施工(gong)倉面噴霧
噴霧(wu)降溫(wen)是(shi)夏季高溫(wen)施工的重要質量保證措施之一。本工程倉(cang)面(mian)安設4臺噴霧(wu)機,同時配有(you)沖毛槍(qiang),對攤鋪的混(hun)凝土表面(mian)不斷噴霧(wu),效(xiao)果較好(hao),未(wei)發現失水變(bian)白,結(jie)硬現象(xiang)。若噴霧(wu)效(xiao)果良好(hao),可(ke)(ke)降低倉(cang)面(mian)溫(wen)度3℃左右(you),減小(xiao)了(le)溫(wen)度倒(dao)灌,營造了(le)適宜澆(jiao)筑(zhu)的倉(cang)面(mian)小(xiao)氣候。國內外資料證明(ming):VC值(zhi)的大小(xiao)與壓實度及強度有(you)密切關系。VC值(zhi)損失在1~2h內影響(xiang)不大,大于2h后VC值(zhi)損失成倍增(zeng)長。通過氣溫(wen)在29℃時,對倉(cang)面(mian)噴霧(wu)和(he)未(wei)噴霧(wu)兩種工況下VC值(zhi)觀測結(jie)果(見表1)可(ke)(ke)知,做(zuo)好(hao)倉(cang)面(mian)噴霧(wu)降溫(wen)工作,減小(xiao)VC值(zhi)損失,必須引起高度重視。
雨天施工
在降(jiang)雨強(qiang)度(du)小(xiao)于3mm/h的(de)條件(jian)下,可覆(fu)蓋防雨布繼(ji)續(xu)施工,當(dang)降(jiang)雨強(qiang)度(du)達到或超過3mm/h時(shi),應停(ting)止拌和,迅速完成尚未進(jin)行(xing)的(de)卸料、平(ping)倉和碾(nian)壓作業,并(bing)采取防雨和排(pai)水措施。當(dang)雨停(ting)時(shi),適當(dang)調大VC值,這樣有利(li)于提高碾(nian)壓層面結合(he)質(zhi)量(liang)。