Abstract
Hydropower projects with dam heights exceeding 200m feature stringent seepage prevention requirements and significant leakage hazards, leading to increasing emphasis on seepage prevention curtains by construction entities. To ensure seepage control effectiveness, designs often adopt elevated grouting pressures. Curtain grouting tests conducted in moderately to highly permeable strata (permeability >10Lu) at the right dam abutment of a 213m-high power station revealed that the grouted formation exhibits characteristics including: large grout intake by open fractures, tendency for non-absorption during re-grouting of setting-waiting hole sections, susceptibility to hydrofracturing during grouting, and inability of two-row curtains to meet the 1Lu seepage prevention standard in relatively high-permeability zones. Subsequent optimization design should incorporate production-scale tests from the main curtain grouting project.
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Preamble
Curtain Grouting Test of Medium to Strong Permeable Granite Formation at a Hydropower Station
Wang Honggang, Gan Yiqiang, Liu Xingguo
POWERCHINA Vibroflotation Construction Engineering Co., Ltd., Beijing 100102, China
Abstract
For hydropower projects exceeding 200 m in height, seepage control requirements are stringent and leakage poses significant hazards, leading to increasing emphasis on impermeable curtains by project owners. To ensure seepage control effectiveness, designers typically select relatively high grouting pressures. Through a curtain grouting test conducted in medium to strong permeable granite formation (permeability >10 Lu) at the right dam abutment of a 213 m high dam project, this study reveals that the grouted formation is characterized by large grout absorption in open fissures, frequent absence of absorption during re-grouting of hole sections after setting, susceptibility to hydraulic fracturing during grouting, and failure of two-row curtain grouting in strongly permeable zones to meet the 1 Lu impermeability standard. Subsequent design optimization should be based on production-scale testing integrated with the main curtain grouting program.
Keywords: grouting pressure; strong permeable formation; curtain grouting test; optimization design