Diversion
Tunnel Concrete Construction Technique of Xiaowan Hydroelectric Station

ZHU Bao-fan   QI Jin-xi

(XIAOWAN FF JOINT VENTURE,YUNNAN FENGQING 675909)

Abstract: Diversion tunnel big concrete lining section of Xiaowan Hydroelectric
Station,full lining section and none-lining section of top arch are 16m×19m and 16m×19.5m（width×height）,because period of dam a river one year ahead, concrete construction
have short period,big section and rigorous technique request,we construct fioor
earlier,border and top area late in construction. Summarizing previous works
experience ,we employ two steel shuttering trolley（each
360t）and  two steel trolley（each 60t）,we consider top arch’s none-lining in designing steel shuttering trolley; After
multi-aspect demonstration ,we exert yielding joint ,solving the general steel
shuttering trolley concrete-placing stagger problems in effect, diversion
tunnel concrete construction proceed in high quality and fast speed , full
lining section place a piece every 4 days and none-lining section of top
section place a piece every 2.5 days,insure the realization of period of dam a
river.

Key words: XiaoWan   diversion tunnel   steel
trolley   steel -shuttering trolley   concrete  
fast   construction technique

1 工程概况及设计参数

小湾水电站初期导流采用土石围堰挡水、隧洞泄流的全年导流方式，初期导流标准按30年一遇洪水重现期设计，相应流量10300m³/s，导流时段为2004年11月~2009年5月。两条导流洞均平行布置于左岸，中轴线间距48m，进口底板高程988m，出口底板高程984.984m，导流洞建筑物级别为Ⅲ级。两条导流洞均由30米进口渐变段，60米的堵头段和标准断面组成，长度分别为861.592m与980.922m，底坡分别为0.3627%、0.3172%，在偏上游的部位有转弯半径为300m的转弯段。

导流隧洞为城门洞型：两端为全断面衬砌段，中部为顶拱不衬砌段。综合分析全衬段及半衬段各占约隧洞总长度的一半。

全断面衬砌段过水断面为16m×19m（宽×高），顶拱不衬砌段过水断面为16 m×19.5m（宽×高），视不同围岩类别衬砌厚度不同，主要有0.55m，1.5m，1m，2.0m四种。

导流隧洞具有运行条件复杂、使用期长、施工期上游河床大量积渣的特点。导流洞底板采用抗冲耐磨性能好、技术经济指标较优的C30微纤维砼（外掺聚丙烯纤维0.9Kg/m3）衬砌，其余边顶拱部位采用普通C30（粉煤灰掺量15％）混凝土衬砌。导流隧洞衬砌主要工程量情况：钢筋制安6437t，现浇砼10.86万m³。