摘要
坝址河谷地形、地质条件往往是决定导流方式的主要因素，各种导流方式须充分利用有利地形，但还必须结合地质条件，有时河谷地形虽适于分期导流，由于河床覆盖层较深，纵向围堰基础防渗、防冲难以处理，纵向导墙难以施工，不得不采取明渠或者隧洞导流方式。在地质条件不成为导流方式选择控制因素的前提下，坝型和河谷地形特点往往是决定导流方案的主要条件，根据国内外上百个工程统计分析，对于当地材料坝，一般采取一次断流隧洞方式或者涵洞导流方式，对于刚性坝，以坝顶长与坝高的比值η=L／h表示河谷形状系数，η〈3时，一般采用一次断流隧洞导流方式；η〉4．5时，一般适合分期导流；3〈η〈4．5时隧洞导流与分期导流均可行。
The valley topographic and geological conditions are the main factors to decide the diversion method. The various diversion methods must make full use of the favorable landform according to the geological conditions. Sometimes the valley topography is suitable for a stage diversion, but the river overburden is thick, it is difficult for longitudinal cofferdam foundation anti-seepage and scour prevention, and also difficult to construct longitudinal di- version wall, so the diversion channel and tunnel have to be adopted. On the premise of that the geological condi- tion does not influence the selection of diversion method, the dam type and valley landform are the main conditions to decide diversion alternative. Based on the statistical analysis of hundreds of hydropower projects at home and a- broad, for the local material dam, generally a cut-off tunnel or culvert diversion is used and for rigid dam, taking η = L/h as the factors of valley shape, a cut-off tunnel is used forη 〈 3 and a stage diversion is used fo η 〉 4.5. tunnel diversion and stage diversion are both practicable for 3 〈 η 〈 4.5. A
关键词
导流方式选择
适宜性分析
导流隧洞
导流明渠
当地材料坝
刚性坝
临时底孔
selection of diversion method
suitability analysis
dam
rigid dam
temporary downholediversion tunnel
diversion channel
local material
